UNIVERSITY OF CALIFORNIA
Santa Barbara
Decline, Movement and Habitat Utilization of the Yosemite Toad (Bufo canorus):
An Endangered Anuran Endemic to the Sierra Nevada of California
A Dissertation submitted in partial satisfaction of the requirements for the degree of
Doctor of Philosophy in
Ecology, Evolution and Marine Biology
by
David Lamar Martin
Committee in charge:
Professor Samuel S. Sweet, Chair
Professor Steve I. Rothstein
Professor Allan Stewart-Oaten
June 2008 3319824
Copyright 2008 by Martin, David Lamar
All rights reserved
3319824 2008
The dissertation of David Lamar Martin is approved.
______Allan Stewart-Oaten
______Steve I. Rothstein
______Samuel S. Sweet, Committee Chair
June 2008
Decline, Movement and Habitat Utilization of the Yosemite Toad (Bufo canorus):
An Endangered Anuran Endemic to the Sierra Nevada of California
Copyright © 2008
by
David Lamar Martin
iii ACKNOWLEDGEMENTS
“The (Yosemite toads) that live on my (forest) are reluctant to
tell me, in so many words, how much of my township is included
within their daily or nightly beat. I am curious about this, for it gives
me the ratio between the size of their universe and the size of mine, and
it conveniently begs the much more important question, who is the
more thoroughly acquainted with the world in which he lives?
Like people, my (toads) frequently disclose by their actions
what they decline to divulge in words. It is difficult to predict when
and how one of these disclosures will come to light.”
With apologies to Aldo Leopold, and A Sand County Almanac, 1949, p. 78.
I am indebted to Dr. Sam Sweet, my dissertation committee chair and major professor, for allowing me the freedom to learn how to conduct science rather than spoon feeding it to me. His example and wisdom in wading through endangered anuran research and the trials and tribulations that come with it, have been formative.
For his comments, suggestions and support of my research I will be forever grateful.
I also extend my sincere gratitude to my other dissertation committee members, Dr. Steve Rothstein, Dr. Allan Stewart-Oaten and early on Dr. John Endler.
I thank Dr. Rothstein for the many conversations and suggestions early in my time at
UCSB that helped guide the direction of my research, for his careful review and helpful suggestions on this dissertation and for filling in as faculty advisor when Dr.
iv Sweet was away on sabbatical. I thank Dr. Stewart-Oaten who contributed a great deal of help with the statistical analysis and graciously stepped up and filled out my committee during the final stretch. I thank Dr. Endler who helped me develop the theoretical perspective under which I tackled my research and provided helpful comments on the first chapter of this dissertation before he retired. Finally, for her judicious application of a cattle prod that forced me to put a period on this albatross, I thank my Graduate Advisor, Dr. Gretchen Hofmann.
Major funding for this research project was provided by a U.S. Fish and
Wildlife Service, Endangered Species Division research grant (#10181-5-1919) supervised by Amadee Brikey, Diane Windham and Steven Morey. Without this funding, and the support of Kathy, Diane and Steve this project would have never gotten off the ground. Additional funding for this research and personal support was provided by my parents, Mr. and Dr. George and Patty Martin, and grandparents, Dr. and Mrs. Lamar and Marguerite Fryer. Personal support was also provided by my brother and sister, Jeff Martin and Debbie Martin. I cannot thank my family enough for sticking by me throughout this process, and especially through the difficult times.
The intensive four years of field work would not have been possible without the assistance and enthusiasm of the field research assistants who generously gave of their time and energies to help me complete this project. First among them is Paulo
Philippidis who stuck with me through two long field seasons. For hiking miles in the snow to get to research sites early in the season, for slogging through mud and cow pies, for tolerating 18 to 20 hour periods of nonstop work without complaining
(much) and for tolerating temperatures ranging from over 32°C to less than -22°C I
v cannot thank you enough! Additional field assistance, for which I am eternally grateful, was provided by Donna Clifton, Brenden Borell and Alan McCready. My two office mates, David Greenberg and John LaBonte, and fellow grad Rocky Strong provided much needed feedback on research ideas, methods of analysis and social interaction. The next round is on me guys.
I would be remiss if I did not thank Dr. Ernest L. Karlstrom, Dr. Martin L.
Morton and Dr. Cynthia Kagarise Sherman for their formative research on which my dissertation is based. Dr. Karlstrom and Dr. Morton were also kind enough to spend many days with me in the field showing me their research sites and providing invaluable insights into the behavior of the Yosemite toad. Thank you very much gentlemen. In addition to assistance with field work, my good friend Alan McCready also generously shared his historical knowledge of Yosemite toad breeding activities and distribution throughout the research project area. Thanks Alan. I also thank Tom
Beck of Stanislaus National Forest who helped with logistical support and assistance in working through Forest Service bureaucracy.
Finally, there are no words to adequately thank the two women in my life who believed in me no matter what, and who provided me with never-ending love and support: my mother, Dr. Patty M. Martin, and my fiancée, Miss Sara E. Johnson. It is to these two women that I dedicate my dissertation. Ladies, I kept my promise and stuck with it!
vi VITA OF DAVID LAMAR MARTIN June 2008
EDUCATION
Bachelor of Science in Biological Science with a Concentration in Zoology, San Jose State University, San Jose, California, May 1989 Master of Arts in Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California, June 2006 Doctor of Philosophy in Ecology, Evolution and Marine Biology, University of California, Santa Barbara, June 2008 (expected)
PROFESSIONAL EMPLOYMENT
1992-2008: Consultant, Environmental and Wildlife Law Enforcement Canorus Ltd., San Jose, California 1993-2002: Teaching Assistant, Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara 1995-2000: Covert Investigator, Division of Law Enforcement, Branch of Special Operations, U.S. Department of Fish and Wildlife, Burlingame, California 1993: Student Research Associate, Sansum Medical Research Foundation, Santa Barbara, California 1990-92: Research Assistant, Osher Molecular Systematics Laboratory, California Academy of Sciences, San Francisco, California 1991: Instructor, Vertebrate Museum Methods, Department of Biology, San Jose State University, San Jose, California 1986-92: Assistant Curator, Museum of Birds and Mammals, Department of Biology, San Jose State University, San Jose, California
PUBLICATIONS
Martin, D.L., M. Olin. 1992. The decline of the Yosemite toad & the role of the modern zoo. Maagizo, 29(7):8-9. Martin, D.L. 1992. Sierra Nevada Anuran Guide. Canorus Ltd. Press, San Jose, CA. Pp 28. Lawson, R., P.G. Frank and D.L. Martin. 1990. A gecko new to the United States herpetofauna with notes on other gekkonids inhabiting the Florida Keys. Herpetological Review, 22(1):11-12.
vii Martin, D.L. 1990. Captive husbandry as a technique to save a species of special concern, the Yosemite toad (Bufo canorus). In R.E. Staub (ed.), Proceedings of the Fifth Conference on the Captive Propagation and Husbandry of Reptiles and Amphibians, pp 16-32. Northern California Herpetological Society, Special Publication No. 6.
AWARDS
U.S. Department of Justice Certificate of Commendation, for outstanding performance and invaluable assistance in support of the activities of the Environment and Natural Resources Division, Washington DC, 2003
Marianna Pisano Memorial Scholarship, for the most outstanding Biological Science student, San Jose State University, San Jose, California, 1991
FIELDS OF STUDY
Major Field: Conservation Biology
Studies in Theoretical Ecology with Professor Samuel S. Sweet
Studies in Evolutionary Biology with Professor John A. Endler
viii ABSTRACT
Decline, Movement and Habitat Utilization of the Yosemite Toad (Bufo canorus):
An Endangered Anuran Endemic to the Sierra Nevada of California
by
David Lamar Martin
Since 1990 there has been an accumulation of evidence suggesting that global amphibian populations have declined. The majority of these declines can be explained by habitat destruction, but some have occurred in seemingly “pristine” habitats such as the high elevation Sierra Nevada mountains of California where the Yosemite toad (Bufo canorus), which is endemic to these “pristine” habitats in the Sierra, has declined. Unfortunately, the designation of “pristine” habitat is based on general management goals rather than on the habitat utilized by amphibians. This study used radio transmitters to track the movements of toads to determine what habitats are utilized and found that adult B. canorus are capable of traveling up to 657m ( x = 278m) from breeding pools to upland foraging habitats, thereby providing a mean total home range estimate for adult B. canorus of 8,457m2, which is considerably larger than previously suggested. Further, this study found that B. canorus conducts much of its movements at night and is therefore not strictly diurnal as previously reported. The habitat utilized by B. canorus was found to include meadows, which were used predominantly by subadult toads and matched the reported preferred habitat of lush meadows with willows and a mean vegetation height of 25cm; upland foraging habitat, which is predominantly occupied by adults and is characterized by rocky substrate and lush vegetation dominated by lupines
ix occurring on mountain slopes with a mean vegetation height of 11cm; and overwintering habitat, which is characterized by a gravel and duff substrate that occurs on the margins of old forest with a mean vegetation height of 3cm. The current management practice of fencing toad breeding pools in meadows may actually increase the impact of cattle grazing on B. canorus terrestrial foraging habitats, thereby having a greater impact on long term population viability, which is a classic example of well intended management practices failing to protect species due to the absence of adequate knowledge of the specialized habitat needs of amphibians. This study suggests the need for a B. canorus core habitat protection zone that extends 500m from the center of all actively used breeding pools.
x TABLE OF CONTENTS
I. THE YOSEMITE TOAD: AN EXAMPLE OF THE GLOBAL AMPHIBIAN DECLINE
CONUNDRUM ...... 1
THEORETICAL BACKGROUND...... 2
Global Amphibian Decline ...... 2
Does the Sierra Constitute “Pristine” Habitat?...... 8
Are Amphibians Good Bio-indicators? ...... 17
Determining the Cause of an Historic Decline ...... 20
The Decline of the Mountain Yellow-legged Frog...... 23
The Decline of the Yosemite Toad ...... 31
STUDY ANIMAL ...... 37
Description...... 37
Range ...... 38
Habitat ...... 39
STUDY AREA ...... 43
Highland Lakes ...... 43
North Pools ...... 44
Mid Pools...... 45
Tryon Meadow...... 46
Highland Lakes Grazing History ...... 48
RESEARCH DIRECTION ...... 51
LITERATURE CITED ...... 54
xi FIGURES...... 88
II. POST-BREEDING MOVEMENTS AND CONSERVATION OF ADULT YOSEMITE TOADS
...... 90
INTRODUCTION ...... 91
MATERIALS AND METHODS...... 94
Study Animal ...... 94
Study Area...... 98
North Pools ...... 98
Mid Pools...... 100
Tryon Meadow...... 101
Stock Grazing on the Highland Lakes Allotment...... 103
Sampling ...... 105
Data Analysis...... 114
RESULTS ...... 123
Toad Tracking...... 123
Overwintering Sites...... 125
Toad Movement Patterns...... 129
Diel Activity ...... 136
Habitat Type ...... 136
Dispersal Distance...... 138
Core Habitat ...... 140
CONCLUSIONS...... 144
LITERATURE CITED ...... 165
xii TABLES ...... 185
FIGURES...... 200
APPENDIX 1 ...... 236
APPENDIX 2 ...... 243
III.HABITAT UTILIZATION OF THE YOSEMITE TOAD: AN ENDANGERED ANURAN.....
...... 263
INTRODUCTION ...... 264
MATERIALS AND METHODS...... 266
Study Animal ...... 266
Study Area...... 269
Sampling ...... 271
Data Analysis...... 275
RESULTS ...... 279
Macrohabitat ...... 279
Microhabitat ...... 289
Cattle Grazing...... 297
CONCLUSIONS...... 299
LITERATURE CITED ...... 308
TABLES ...... 317
FIGURES...... 351
APPENDIX 1 ...... 366
xiii
CHAPTER I
THE YOSEMITE TOAD (Bufo canorus, CAMP):
AN EXAMPLE OF THE GLOBAL AMPHIBIAN DECLINE
CONUNDRUM
1 THEORETICAL BACKGROUND
Global Amphibian Decline
Since 1990 there has been an explosion of interest in the plight of amphibians around the world resulting from the workshop titled, “Declining Amphibian
Populations—A Global Phenomenon?” which was organized by Wake and Morowitz and sponsored by the National Research Council’s Board on Biology (Wake &
Morowitz 1990). The workshop report of findings found fragmentary and anecdotal evidence suggesting that a global amphibian decline (GAD) may have occurred, and subsequent research has supported this contention (see, Houlahan et al. 2000; Stuart et al. 2004). The workshop report of findings also found that there was no evidence to suggest that there was a single global cause for the reported amphibian declines, and to the contrary, the majority of extinctions and declines reported at the workshop appeared to be the result of drastic local habitat modification and/or other anthropogenic causes. However, the report also found that “…the decline and extinction of some amphibian populations in seemingly pristine areas cannot be directly tied to human activities,” suggesting that other more subtle effects are involved in the observed GAD (Wake & Morowitz 1990, p. 2; see also, Barinaga
1990; Blaustein & Wake 1990). Amphibian species occupying montane habitats are therefore taking on an increasingly important role in the study of GAD owing largely to their mysterious population reductions in seemingly “protected” or “pristine” habitats (Blaustein & Wake 1990; Wake & Morowitz 1990; Travis 1994; Blaustein &
Wake 1995; Morrison & Hero 2003; Beebee & Griffiths 2005).
2 The assumption that “[m]any montane (amphibian) species of western North
America are in decline, even in protected preserves and undisturbed areas where habitat alteration is not apparent” (Wake & Morowitz 1990, p. 2) has fed the idea that much of the GAD conundrum is the result of some yet to be identified, or
“mysterious,” global factor rather than habitat alteration per se. One example used during the GAD workshop of an amphibian species declining in seemingly “pristine” habitat was the Yosemite toad (Bufo canorus), a high-elevation Sierra Nevada endemic, that appears to have suffered a precipitous decline throughout its range for largely unknown reasons (Wake 1990; Martin 1990; Bradford et al. 1991; Martin
1991a, b; Bradford & Gordon 1992; Kagarise Sherman & Morton 1993; Martin 1993;
Martin et al. 1993; Jennings & Hayes 1994; Martin 1994; Stebbins & Cohen 1995;
Drost & Fellers 1996; Jennings 1996), resulting in this species being found to be
“warranted” for listing under the Endangered Species Act “but precluded by higher priority listing actions” (50 CFR 17 75834). Approximately 99% of the land within the range of this species is federally managed lands comprised predominantly of
National Forests and National Parks (Williams 2002) which are seemingly protected from overt habitat destruction. It is clear that direct factors, such as the construction of a shopping mall, can have a devastating impact on local populations, but clearly do not have a global or even regional influence on amphibian species decline, and are certainly not a factor in the decline of B. canorus. However, indirect effects of human activities such as pesticide drift or a reduction in the ozone layer thereby increasing exposure to ultraviolet light (UV) could have regional or even global consequences for amphibian species that could reduce populations in a manner that is
3 more difficult to detect (Blaustein & Wake 1990; Wake & Morowitz 1990; Blaustein
& Wake 1995; Blaustein et al. 1998; Davidson et al. 2002; Davidson 2004).
The prevailing assumption that amphibian species have declined in “pristine habitat” has subsequently led to a considerable amount of research into previously unknown and unmeasured indirect factors that could explain landscape level changes in amphibian distribution and abundance such as acid precipitation (Bradford &
Gordon 1992; Corn & Vertucci 1992; Bradford et al. 1994a; Vertucci & Corn 1996), diseases (Scott 1993; Berger et al. 1998; Daszak et al. 2001; Fellers et al. 2001; Green
& Kagarise Sherman 2001; Rachowicz 2002; Lips et al. 2003; Morehouse et al. 2003;
Muths et al. 2003; Burrowes et al. 2004; Rachowicz & Vredenburg 2004; Briggs et al. 2005; Rachowicz et al. 2005; Rachowicz et al. 2006), pesticides and other toxicants (Hall & Henry 1992; Hecnar 1995; Noriega & Hayes 2000; Davidson et al.
2001; Sparling et al. 2001; Davidson et al. 2002; Hayes et al. 2002; Davidson 2004;
Fellers et al. 2004), ultraviolet (UV) radiation (Blaustein et al. 1994a; Blaustein et al.
1996; Hays et al. 1996; Blaustein & Kiesecker 1997; Blaustein et al. 1998; Belden et al. 2000; Broomhall et al. 2000; Kats et al. 2000; Blaustein & Belden 2003; Heyer
2003; Licht 2003), global climate change (Alexander & Eischeid 2001; Blaustein et al. 2001; Carey et al. 2001; Pounds 2001; Carey & Alexander 2003; Corn 2003,
2005), and a combination of these factors (Carey 1993; Kiesecker & Blaustein 1995;
Boone & Semlitsch 2001; Carey et al. 2001; Kiesecker et al. 2001; Davidson et al.
2002; Blaustein et al. 2003; Hatch & Blaustein 2003). However, research efforts into the indirect factors above have thus far failed to demonstrate a cause and effect relationship between the factors under study and amphibian population declines at the
4 landscape level (Pechmann et al. 1991; Pechmann & Wilbur 1994; Hero & Gillespie
1997; Alford & Richards 1999; Biek et al. 2002; Semlitsch 2003b; Semlitsch &
Rothermel 2003; Beebee & Griffiths 2005), leaving land managers somewhat
wanting when it comes time to make real world management decisions to protect
amphibian populations from further decline. This is a common criticism of the field
of conservation biology as a whole; namely that when confronted with real world
species and ecosystem management issues, such as the rapid decline of a species,
standard ecological models and theory offer little insight into the problem (McIntosh
1985; Peters 1991; Pimm 1991; Shrader-Frechette & McCoy 1993; McCoy 1994;
Sarkar 1996).
Further confusing the issue are studies of several of the indirect factors
identified above that suggest that they are probably not contributing to the observed
GAD (e.g. acid precipitation (Bradford & Gordon 1992; Bradford et al. 1992;
Bradford et al. 1994a; Bradford et al. 1994c), diseases (McCallum & Dobson 1995;
Alford & Richards 1997; Hero & Gillespie 1997; Green & Kagarise Sherman 2001;
Cleaveland et al. 2002; Retallick et al. 2004; Briggs et al. 2005), pesticides and other toxicants (Davidson et al. 2002), UV radiation (Jennings 1996; Licht 1996; Licht &
Grant 1997; Palen et al. 2002; Bridges & Boone 2003; Licht 2003; Little et al. 2003;
Adams et al. 2005)). More importantly the focus on indirect factors thought to be contributing to the observed amphibian decline in allegedly “pristine” environments, combined with the uncertainty as to the roles played by indirect factors in GAD, is being used to dismiss the effects of habitat alteration on amphibians resulting from ongoing management activities in the Sierra Nevada. This is especially disturbing
5 given that management activities in the Sierra Nevada, such as livestock grazing, are well known to have both short and long-term adverse impacts on the environment
(see, Armour et al. 1991; Platts 1991; Armour et al. 1994; Fleischner 1994; Trimble
& Mendel 1995; Erman 1996; Jennings 1996; Kattelmann & Embury 1996; Kie &
Boroski 1996; Kinney 1996; Knapp & Matthews 1996; Menke et al. 1996;
Magilligan & McDowell 1997; Belsky et al. 1999; Flenniken et al. 2001; Jansen &
Healey 2003; Cole et al. 2004; and sources cited therein). For example, the Sierra
Nevada Forest Plan Amendment (SNFPA): Management Review and
Recommendations (USDA 2003, p. 70-71) states:
“Upon review, we found that anecdotal information suggests that grazing directly effects toads by trampling individuals, and indirectly, by altering hydrological systems. No data is provided in the FEIS [Final Environmental Impact Statement] to quantify these effects or to show the relative significance of the effects in contributing to the observed population decline. We are aware that the working group for the Yosemite Toad Conservation Assessment has identified trampling and/or crushing of adults and metamorphs and changes in the hydrological function of meadows as potential threats to the species. Other information suggests that the decline in Yosemite toad populations may not be strongly linked to grazing activity. This includes the one research study specific to Yosemite toads that is cited in the FEIS. The study supports the observation that populations are declining, however, no grazing occurred in the study area (Kararise (sic), Sherman and Morton, 1993). Moreover, base line population estimates for Yosemite toad are derived from museum records and historical sightings reported over the same period of time that intensive grazing was taking place over vast areas of the Sierra
6 Nevada. We note that the observed decline in the number and distribution of Yosemite toads in the Sierra is coincident with a significant reduction in grazing in the same location. These observations cause us to question the extent to which further restrictions on grazing will have any effect on the ability of the species to overcome more significant environmental stressors. The fundamental problem, as reported in the Sierra Nevada Ecosystem Project and many other sources referred therein, is that there is simply a great deal of scientific uncertainty about the reasons for the decline in amphibian populations over a broad geographic scale. Other potential impacts to the species and its habitats are reported as: • Drought • Disease • Predation • Chemical toxins • Recent increases in UV radiation • Stocking of non-endemic sport fish”
While this statement acknowledges grazing has had some detrimental impacts on
B. canorus populations, it fails to acknowledge the vast body of published peer reviewed studies which indicate that grazing has cumulative detrimental effects on the environment (see, Kinney 1996; Menke et al. 1996; sources cited therein and below), nor does it recognize the landscape scale of contemporary and historic grazing impacts on environments in the Sierra Nevada (see, Kinney 1996; Menke et al. 1996; and below). Further, the SNFPA statement suggests that the indirect factors, some of which have studies published in peer reviewed journals that indicate
7 they have little or no impact on amphibian populations (see above), are of equal or
greater importance in the decline of B. canorus than livestock grazing, which has known detrimental impacts on the environment utilized by B. canorus and is remediable by changes in land management practices. Finally, the SNFPA statement fails to point out that there are no published studies that suggest grazing is beneficial to B. canorus populations in any way. Clearly, the conventional wisdom assigning a
“pristine” or “protected” habitat label to environments in the Sierra Nevada resulting from the GAD workshop is being used to downplay past environmental damage caused by land management activities in the Sierra Nevada, and is also being used to continue those activities in the future under the color of the “scientific uncertainty” created by the plethora of proposed hypotheses for the decline of amphibian populations in seemingly “pristine” environments.
This paper will reexamine the underlying assumption that habitat in the Sierra
Nevada is “protected” or “pristine”, and then question the conventional wisdom behind, and focus of, GAD research thus far, in an effort to provide land managers with a framework within which a biologically based recovery plan for B. canorus and other Sierra Nevada amphibians can be developed that has a realistic possibility of being effective in promoting recovery of amphibian populations.
Does the Sierra Constitute “Pristine” Habitat?
The heavy GAD research emphasis on indirect landscape level factors has
taken much of the attention away from the underlying assumption that montane
8 regions of the New World have “pristine” habitat even though many of the landscape level factors thought to be affecting amphibians are, in fact, human induced. Even if one argues that these indirect factors do not constitute direct habitat degradation in the traditional sense, it is clear that human induced direct habitat degradation has occurred throughout the western United States, including within the montane
“protected preserves and undisturbed areas” discussed in the workshop report (see,
Wake & Morowitz 1990, p. 2) and has thus had a landscape level impact on amphibian populations.
The Sierra Nevada of California, for example, is comprised largely of
National Forests (NFs), which are considered to be “protected” from overt habitat destruction, as well as Wilderness Areas and National Parks (NPs), which are considered “pristine.” Unfortunately, the perception that an area is “protected” from anthropogenic effects or “pristine” is a subjective determination made by humans that has little to do with how amphibians view their habitats (see, Pechmann & Wilbur
1994) and everything to do with the management strategy of the public lands in question. Further, these subjective concepts fail to take into account the historical environmental impacts on the lands in question.
The NFs of the Sierra Nevada manage their lands for “multiple use” which allows and even promotes such activities as logging, livestock grazing (cows and sheep) packstock grazing (which is defined as horses, mules and other animals used to carry people and supplies over mountain trails), mining, water storage, power production, road construction, and recreation that includes off-highway vehicle use, skiing, hiking, camping, backpacking and game species production for hunting and
9 fishing. All of these activities have some attendant benefit to man; but they also have impacts, both direct and indirect, on the environment, including the destruction or alteration of amphibian habitat (Fleischner 1994; Linder et al. 1994; Dupuis et al.
1995; Bull & Hayes 2000; Knapp et al. 2001a; Johnston & Frid 2002; Vesely &
McComb 2002; Pilliod et al. 2003). The higher elevation areas of NFs in the Sierra
Nevada are generally designated as wilderness areas, where logging activities, road- building, vehicle transport, and power production are prohibited; but grazing, mining and all of the other recreation activities, which have known direct impacts on the environment, are permitted. Given that all of these direct anthropocentric environmental impacts occur in NF wilderness areas, not to mention the possible effects of the indirect factors, it seems hardly reasonable to classify wilderness areas as “pristine.”
The NPs in the Sierra Nevada have a different management strategy that puts more emphasis on protecting the environment and wildlife than is the case in the NFs.
For example, the highly destructive activities permitted in NFs, such as logging, mining, off-highway vehicle use, hunting, cattle and sheep grazing are, for the most part, no longer permitted in the NPs. However, human recreation activities play a much greater role in the management of NPs because the NPs receive many more human visitors each year than the NFs, which equates to a much greater density of campgrounds, hotels and visitor-support facilities in the NPs than occurs in the NFs.
Vehicle traffic alone in NPs is so much greater than in NFs that smog in some areas in the NPs can reach levels found in major U.S. cities (e.g., Yosemite Valley, Coile
2004). The use of packstock transport and thus, packstock grazing, is also much
10 greater in the NPs, owing to the greater number of visitors. The designated
wilderness areas within NPs, like NFs, restrict vehicle traffic; but the larger number
of visitors in the back country of NPs each year suggests greater direct human
impacts on the environment in NP wilderness areas than for those in NFs. However,
the amphibian habitat within the NP wilderness areas appears to be in better condition
than the comparable habitat in NF wilderness areas (Martin 1991a, b; Bradford et al.
1994b), which is likely the result of the exclusion of cattle grazing from the NPs
(Martin 1991a, b). Even with the increased protection afforded to wilderness areas in
NPs, they can hardly be termed “pristine,” and this is especially the case when one
includes some of the indirect landscape level factors, such as the impact of global
climate change (Pupacko 1993; Dettinger & Cayan 1995; Blaustein et al. 2001;
Pounds 2001; Root et al. 2003; Corn 2003; Sanders 2003; Corn 2005) and possible pesticide deposition in these areas (Davidson 2004).
Other very important but often overlooked components of habitat conditions in the Sierra Nevada are the historical roles that extinction and over-exploitation play on current environmental conditions. For example, the two top predators in the Sierra
Nevada ecosystem, the gray wolf (Canis lupus) and grizzly bear (Ursus chelan californicus), have been extinct in the Sierra Nevada since the mid-1920s (Storer &
Tevis 1955; Ingles 1965; Schmidt 1987, 1991; Williams & Nowak 1993). It is difficult to say how the absence of these top predators has affected the Sierra Nevada ecosystem because these animals were hunted to extinction before much was known about their autecology and ecosystem interactions in the Sierra. However, the reintroductions of wolves and grizzlies into the Rocky Mountains of Wyoming and
11 Montana, respectively, have resulted in dramatic ecosystem improvements. In
Yellowstone NP, the reintroduction of wolves has had a ripple effect through three
trophic levels of the food chain, resulting in recovery and stabilization of riparian
plant communities and an increase in biodiversity (Ripple & Beschta 2003). In
Glacier NP, the reintroduction of grizzlies has resulted in the restructuring of
subalpine meadow plant communities by the bears digging for preferred forage plant
bulbs within meadows and by influencing nitrogen availability to plant communities,
thereby altering the successional dynamics of subalpine meadows (Tardiff & Stanford
1998; see also, Doak & Loso 2003). Increased complexity and stability of riparian
and subalpine meadow ecosystems in the Sierra Nevada could have large positive
benefits for amphibian species and their habitat. In particular, the habitat of Bufo
canorus could benefit greatly by the change in successional dynamics of subalpine meadows that could result from the reintroduction of grizzlies into the Sierra.
Another often overlooked example of historic Sierra Nevada ecosystem
impact is the over-exploitation of meadow plant communities by intensive livestock
grazing. Early records of grazing activities in the Sierra Nevada are scarce, but it
appears that livestock were first introduced into the Sierra Nevada by Spanish settlers
in the mid-1700s; however, grazing did not have an extensive impact on Sierra
Nevada ecosystems until after the Gold Rush in the early- to mid-1860s (Menke et al.
1996). It is ironic that when John Muir first arrived in what was to become Yosemite
NP in the summer of 1869, it was to work as a shepherd (Kinney 1996); but by 1877
Muir had become an ardent critic of sheep grazing owing to the year-round,
unregulated overgrazing by large bands of transient sheep throughout much of the
12 Sierra and the setting of large fires every fall by sheepherders for the purpose of
opening montane slopes and chaparral shrub land areas for grazing (Thilenius 1975;
Ratliff 1985; Kinney 1996; Menke et al. 1996). He wrote of “…the comprehensive destruction caused by ‘sheepmen.’ Incredible numbers of sheep are driven to the mountain pastures every summer and their course is ever marked by desolation…, the shrubs are stripped of leaves as if devoured by locusts, and the woods are burned”
(Muir 1877; as cited in Kinney 1996, p. 41).
Public stewardship of the Sierra began with the creation of Yosemite, Kings
Canyon, and Sequoia NPs in 1890 and with the establishment of the Sierra Forest
Reserve in 1893, which brought about the first attempts to restrict and/or regulate grazing in the Sierra (Kinney 1996; Menke et al. 1996). Unfortunately, enforcement of the new restrictions by the U.S. Army was hampered by inadequate enforcement penalties and troop redeployment owing to the Spanish-American War. By 1900, sheep grazing was largely restricted from the NPs, which resulted in an increase in grazing of surrounding Forest Reserves, but the damage to the NPs by 50 years of overgrazing and burning by sheep ranchers to improve forage yields caused much damage to the plant communities (Kinney 1996; Menke et al. 1996). According to
Sudworth and Gannett (1900; as cited in Kinney 1996, p. 42), “There are practically no grasses or other herbaceous plants. The forest floor is clean. The writer can attest the inconvenience of this total lack of grass forage for in traveling over nearly
3,000,000 acres not a single day’s feed for saddle and pack animals was secured on the open range… Barrenness is, however, not an original sin. From a study of long- protected forest land in the same region and from the statements of old settlers, it is
13 evident that formerly there was an abundance of perennial forage grasses throughout this territory…” Once sheep grazing was restricted in the NPs, plant communities began to recover, but the effects of this overgrazing can still be seen in plant communities and stream hydrology today (Burcham 1957; Kinney 1996). In 1908, the fledgling NFs took over management and gradually brought transient sheep grazing under control. The largest changes in grazing practice occurred in the early
1920s when cows began to gradually take over the grazing allotments in the Sierra due to fire suppression, reducing sheep forage to below economically viable levels, and a foot-and-mouth disease outbreak throughout much of the central Sierra, resulting in the destruction of most of the remaining sheep bands. From the 1920s through the 1970s there has been a gradual decrease in cattle grazing in the Sierra, which was brought about in part by the Taylor Grazing Act of 1934 that heralded the idea of sustainable range management. There was a slight increase in cattle grazing in the early 1940s due to the pre-war build-up, but high transportation costs during the war kept cattle numbers in check. Beginning in the early 1980s, grazing management began to focus on “resource” protection, prompted by the writing of wilderness management plans and the poor range conditions resulting from the long history of overgrazing throughout much of the Sierra (Kinney 1996; Menke et al.
1996).
The exclusion of sheep and cattle grazing from the NPs since the early 1900s should not be used to support the idea that habitats in the NPs have since recovered from overgrazing. While superficial inspection of riparian plant communities may give the appearance of vegetative recovery in some areas, the hydrology of stream
14 channels and associated meadows that have been deeply incised by years of overgrazing may take hundreds or even thousands of years to recover (Fleischner
1994; Trimble & Mendel 1995; Clary et al. 1996; Kattelmann & Embury 1996;
Belsky et al. 1999). Further, soon after the creation of the NPs, packstock became an important part of recreation support infrastructure (Jackson 2004). The impact of packstock grazing on the habitat in the NPs became immediately apparent and perpetuated the hydrologic damage wrought by sheep before the restriction of livestock grazing. Recreation in the NPs increased dramatically after World War II and continues to this day with few high Sierran meadows being spared from recreational and/or commercial packstock grazing. In the high Sierra, packstock is now considered the primary agent of grazing impact (Sumner & Leonard 1947;
Menke et al. 1996; Belsky et al. 1999). In total, approximately 89% of the vegetated land in the Sierra Nevada remains subject to livestock and/or packstock grazing
(Davis & Stoms 1996).
In summary, although the habitat in the Sierra Nevada is generally defined as
“protected” and/or “pristine” for the purposes of resource management, this is clearly not the case. Since much of the GAD research conducted thus far has focused on determining the indirect landscape level factors causing the apparent decline in
“pristine” environments, a potentially important component of the decline of amphibian populations in the Sierra Nevada (and other montane regions of the western United States and Canada) is being largely overlooked, namely the more subtle forms of direct habitat alteration caused by ecosystem management for anthropocentric needs that result in an environment which is far from “pristine” and
15 is likely impacting amphibian population recovery . Therefore, research energies should be less focused on the indirect or “mysterious” landscape level factors suggested by the GAD workshop and more focused on direct amphibian habitat degradation caused by management activities in the so-called “protected” and/or
“pristine” habitats. This is not to suggest that the indirect landscape level factors being studied are not an important area of GAD research, but rather that research into the effects of management activities on anuran populations may produce a more tractable and immediate method for land managers to improve amphibian habitat and thus promote population recovery than is likely to result from research into the more global indirect factors that will likely take decades to address, let alone ameliorate
(for similar arguments see Beebee 1996; Semlitsch 2002; Semlitsch & Rothermel
2003; Beebee & Griffiths 2005). Further, research into the habitat needs of amphibians may also suggest that historic habitat degradation in the Sierra may have
“set the stage” (e.g. the "perched faunas" concept proposed by Johnson 1974) for what appeared to be a synchronous anuran species decline (e.g., Rana auora, R. boylei, R. muscosa and B. canorus, Bradford 1983, 1991; Bradford et al. 1991;
Martin 1993; Martin et al. 1993; Jennings & Hayes 1994; Martin 1994; Stebbins &
Cohen 1995; Drost & Fellers 1996; Jennings 1996); or put another way, subtle habitat degradation created conditions whereby amphibian populations were more susceptible to global or regional agents of decline than would have been the case under truly “pristine” conditions (Martin 1991b; Pechmann & Wilbur 1994). Thus, research on the effects that more subtle but direct forms of habitat degradation have on amphibian populations may not only assist with population recovery but may also
16 help bolster the surviving populations from future stochastic events including the effects of the more indirect global factors such as climate change.
Are Amphibians Good Bio-indicators?
A second very influential component of the Declining Amphibian Populations
Workshop report of findings was the suggestion that amphibians have “special properties” that make them sensitive bioindicators of environmental health. In particular, the report suggested that the highly vascularized, moist permeable skin of adult amphibians (which is used as a respiratory organ in many species and for osmoregulation in most species), gills (which are present in at least the larval stage), and aquatic embryos (which have membranes that are permeable to liquids) allow the direct absorption of toxins from the air, substrate and/or water. Thus, it was suggested in the report of findings that amphibians might be more sensitive to toxins in the environment than any other group of vertebrates. It was further noted that most amphibians have biphasic or complex life histories whereby aquatic eggs and larval forms, which consume detritus and plant materials, then develop into terrestrial adult forms, which consume insects, other invertebrates and even small vertebrates. Thus, amphibians are exposed not only to toxins directly in both the terrestrial and aquatic environments but also indirectly through their exposure to different trophic levels of the food chain which, the report suggests, could make amphibians very sensitive indicators of ecosystem health (Barinaga 1990; Blaustein & Wake 1990; Wake &
Morowitz 1990; Wyman 1990).
17 Often missed, however, is that the litany of properties purported to make
amphibians sensitive bio-indicators also makes it exceedingly difficult to use them to
reveal where a problem occurs within the ecosystem due to the large number of
possible biotic, abiotic and demographic causes for an observed amphibian decline.
A good bio-indicator, on the other hand, should serve as a surrogate measure of
environmental contamination, habitat quality and/or population trends in other
species; and the co-variation between the abundance of the indicator-species and the
parameter of interest must be strong, well understood and easy to measure (Landres et
al. 1988; Noss 1990; Simberloff 1998; Caro & O'Doherty 1999; Beebee & Griffiths
2005). However, there is very little research demonstrating co-variation between amphibian abundance and other parameters of interest (Beebee & Griffiths 2005).
“Some of the early amphibian decline literature, therefore represents a paradox – amphibians were flagged as good biological indicators despite the fact that the authors concerned had little idea at the time what they were indicating!” (Beebee &
Griffiths 2005, p. 278). Further, there is little evidence to suggest that amphibians as a group are better bio-indicators than other taxonomic groups (Pechmann & Wilbur
1994; Kati et al. 2004; Lawler et al. 2003 as cited in Beebee & Griffiths 2005). The particular features thought to make amphibians as a group sensitive bio-indicators,
namely the biphasic life history and permeable skin and eggs which are thought to
make them vulnerable to environmental change or contaminants and thus, good
indicators (Barinaga 1990; Blaustein & Wake 1990; Vitt et al. 1990; Wake &
Morowitz 1990; Wyman 1990), may not provide an accurate assessment of
environmental perturbations. Different species of amphibians are exposed to
18 stressors in the aquatic and terrestrial environments for different periods of time, likely resulting in a considerable imbalance between these stressors for different amphibian species. Further, there is considerable variation in sensitivity to contaminants among amphibian species, and almost no studies supporting the contention that amphibians as a group are more sensitive to contaminants than other taxa (Beebee 1992; Hall & Henry 1992; Pechmann & Wilbur 1994; Zhang 1999;
Beebee & Griffiths 2005). In short, the complexity of amphibian biology, variation in life history strategies and variation in sensitivity to contaminants make amphibians, as a group, poor indicators of a specific environmental problem and very poor at identifying where that problem is occurring within the ecosystem and thus, poor bio- indicators.
However, in many cases amphibians can still be considered heralds of general
(versus specific) environmental degradation. This is particularly true when a large proportion of the species and/or populations in a given region all share the same pattern of decline as is apparently the case for anurans in the Sierra Nevada of
California (Bradford & Gordon 1992; Martin 1993; Martin et al. 1993; Jennings &
Hayes 1994; Martin 1994; Drost & Fellers 1996; Jennings 1996). So, while amphibians do not make good bio-indicators, they are good early indicators of general environmental degradation.
19 Determining the Cause of an Historic Decline
Another key but largely ignored problem with GAD research is that in many cases, including the Sierra, amphibian populations declined in the late 1970s and early 1980s but have since generally failed to rebound (Kagarise Sherman 1980;
Kagarise Sherman & Morton 1984; Martin 1990; Wake & Morowitz 1990; Bradford
1991; Martin 1991a, b; Kagarise Sherman & Morton 1993; Martin et al. 1993;
Jennings & Hayes 1994; Drost & Fellers 1996; Jennings 1996; Houlahan et al. 2000).
It has been shown that natural amphibian populations fluctuate substantially, and it has also been shown that once environmental perturbations such as drought have alleviated, populations can quickly recover (Pechmann et al. 1991; Pechmann &
Wilbur 1994; Alford & Richards 1999; Marsh 2001). This has led to the assumption that past factors initially causing populations to decline have continued to affect populations in the present and thus, it is believed, any factor that is presently impacting populations therefore must be the cause of the original decline (e.g., Drost
& Fellers 1996; Fellers et al. 2004). I submit that this is not necessarily the case because it is well established that the susceptibility of a population to various agents of decline or extinction change with the size of the population (e.g., MacArthur &
Wilson 1967; Simberloff & Abele 1975; Soulé & Wilcox 1980; Wilcox 1980; Frankel
& Soulé 1981; Shaffer 1981; Hanski 1982, 1983; Diamond 1984; Soulé 1985, 1986,
1987; Hanski 1989; Hanski & Gilpin 1991; Caughley 1994). Put another way, the factor performing the final death blow to a small declining population or species can have very little to do with the original factor or combination of factors that sent it on
20 a course toward the final extinction event (Harrison 1991; Williams & Nowak 1993;
Simberloff 1994; Hanski et al. 1996). Thus, concentrating research efforts solely on factors that may have caused a population to decline at some point in the past (e.g.,
Carey 1993; Blaustein et al. 1994a; Blaustein et al. 1994b; Blaustein et al. 1995;
Carey & Bryant 1995; Laurance et al. 1996; Lips 1998; Davidson et al. 2001; Fellers et al. 2001; Middleton et al. 2001; Fellers et al. 2004) may miss the more proximate factors that will ultimately result in population extinction. Given that the primary goal of conservation biology is to prevent species from going extinct (Soulé 1986), it would seem more prudent to focus research energies on factors that are currently affecting populations that may ultimately result in the extinction of local populations and/or the species.
The difficulty of trying to establish the initial causative agent of amphibian decline is further emphasized by the fact that declining amphibian populations were defined as such only after they had already been in a state of decline for several years
(see, Wake & Morowitz 1990; Blaustein & Wake 1990; Bradford 1991; Wake 1991;
Kagarise Sherman & Morton 1993; Blaustein & Wake 1995). Therefore, the kinds of detailed contemporaneous studies necessary to establish cause and effect relationships between declining populations and the suggested original causative factors, which were also largely unmeasured at the time of the decline, are lacking
(e.g., Kagarise Sherman 1980; Morton 1982; Bradford 1983, 1991; Crump et al.
1992; Kagarise Sherman & Morton 1993; Carey 1993; Blaustein et al. 1994a;
Blaustein et al. 1994b; Bradford et al. 1994a; Pounds & Crump 1994; Hecnar 1995;
Berger et al. 1998; Lips 1998; Broomhall et al. 2000; Fellers et al. 2001; Green &
21 Kagarise Sherman 2001; Sparling et al. 2001; Davidson et al. 2002; Green et al.
2002; Licht 2003; Blaustein et al. 2003; Hatch & Blaustein 2003; Burrowes et al.
2004; Davidson 2004; Fellers et al. 2004; see also, Pechmann et al. 1991; Pechmann
& Wilbur 1994). This kind of historical research is further hampered by the indirect evidence (e.g. patterns of decline) for causative factors, which in many cases could be explained by more than one of the competing hypothesized factors (Jennings 1996;
Jennings & Hayes 1994; Davidson et al. 2001; Pechmann & Wilbur 1994). This means that it is highly unlikely that the factor or factors responsible for the original population declines will ever be conclusively established (for an analogous argument see Alvarez et al. 1980). Therefore, the truly important question for amphibian decline research is not determining what factors contributed to the initial or rapid decline of a species but rather which factors, if altered, can prevent population extinction and promote population recovery, or at least “buy time” for the larger, more difficult factors to be addressed or ameliorated (Beebee 1996; Semlitsch &
Rothermel 2003). This approach switches the focus of GAD research from a primarily historical or observational perspective, where hypothesis testing is difficult or impossible, to one that is predictive, where cause and effect relationships between factors currently affecting amphibians and population dynamics can be established through rigorous testing, and management decisions can be made with some degree of confidence. This approach has the added advantage of being able to identify and ameliorate the original cause of the decline if it happens to still be affecting amphibian population dynamics.
22 The Decline of the Mountain Yellow-legged Frog
The mountain yellow-legged frog (Rana muscosa) is a good example of the benefits that can be afforded amphibian species when the more proximate factors affecting populations are studied. Rana muscosa occurs predominantly in the high- elevation (1370-3650 m) portions of the Sierra Nevada mountains of California, and at higher elevations (≥ 1460 m) its range is overlapped by that of B. canorus
(Stebbins 1985). Local populations of adult R. muscosa studied at 27 high-elevation lakes in Sequoia National Park, California, were observed to decline after unusually deep snow pack accumulated during the winters of 1977-1978 and 1978-1979, which resulted in many of the shallower lakes (<4 m deep) being frozen to the bottom (due to the build-up of snow forcing the ice sheet deeper into the lake) and the remaining lakes having an unusually thick ice cover (Bradford 1983). At the time, the disappearance of adults from the study populations was thought to be the result of oxygen deprivation on the bottoms of the frozen lakes where these frogs are known to over-winter (Bradford 1983; however see Matthews & Pope 1999). A later study
(Bradford 1991) documented an apparent “red-leg” disease outbreak among the surviving adult frogs at two lakes during the summer of 1979, which decimated the adult populations in these two habitats, and Brewer’s blackbirds (Euphagus cyanocephalus) eliminated recruitment to the adult population at one of these lakes and severely limited recruitment at the other lake by preying on metamorphosing tadpoles. Recolonization of the lake habitat left behind by these mortality events and subsequent local population extinctions was considered unlikely to occur due to
23 isolation from the surviving local R. muscosa populations. Isolation of surviving R.
muscosa populations was effected by introduced fish that had eliminated frogs from
the interconnecting waterways and nearby lakes through predation on larval and adult
life stages (Bradford 1989, 1991; Bradford et al. 1993; Bradford et al. 1994b).
Much of the Sierra was devoid of fish until the stocking of trout (Salmo spp.)
and charr (Salvelinus spp.) for sport fisheries began over 120 years ago in the early
1870s (Shebley 1917; Snyder 1933; Hubbs & Wallis 1949; Moyle 1976; Pister 2001).
The practice of stocking Sierra lakes with non-native fish continued almost unchallenged until 1977 when the Sequoia, Kings Canyon and Yosemite National
Parks began to phase out fish stocking; but up to 70% of the previously stocked lakes continue to support self reproducing trout or charr populations, and the practice of stocking fish continues on “protected” National Forest lands, which includes
“pristine” wilderness areas (Pister 2001; Knapp 2002; Armstrong & Knapp 2004).
The apparent adverse relationship between introduced fish and native R. muscosa
populations in high-elevation lakes has been observed anecdotally for over 80 years
(Grinnell & Storer 1924; Walker 1946; Cory 1963; Zardus et al. 1977; Hayes &
Jennings 1986), but Bradford (1989) was the first to formally study the distribution of
frogs in relation to fish in the Sierra. He found an allotopic distribution of R.
muscosa and introduced fish with shallower lakes (≤~1.5 m), in which fish cannot
survive the winter, tending to be occupied by frogs, and larger lakes and streams
tending to be occupied by fish. Interestingly, however, large R. muscosa populations
were known to occur in deep lakes if fish were not present (Grinnell & Storer 1924;
Bradford 1989). The resulting isolation of the remaining populations of R. muscosa
24 by distance and fish predation effectively eliminated the possibility of recolonizing
fishless habitats after the isolated local populations occupying them went extinct
(Bradford 1989; Bradford et al. 1993).
At the GAD workshop Bradford presented his data, and the anecdotal
observations of others including my own, regarding the apparent sudden decline of R.
muscosa populations throughout the Sierra during the late 1970s and early 1980s, as
well as the apparent declines in B. canorus populations during the same period (pers.
notes from workshop), which were interpreted as evidence for an enigmatic
amphibian decline in “protected” high-elevation habitats (Blaustein & Wake 1990;
Wake & Morowitz 1990). There have been several subsequent survey efforts that
support the hypothesis that a precipitous decline in both distribution and abundance
of R. muscosa has occurred throughout the entire Sierra Nevada (Bradford 1991;
Bradford et al. 1993; Martin 1993; Martin et al. 1993; Bradford et al. 1994b; Jennings
& Hayes 1994; Martin 1994; Drost & Fellers 1996; Knapp 2005), but other than the
local populations of R. muscosa studied by Bradford, there is only anecdotal evidence
indicating the timing of this apparent decline and its cause. Since the GAD workshop
a considerable effort has been put forward studying several of the proposed indirect factors believed to be responsible for the decline of R. muscosa including acid precipitation (Bradford et al. 1991; Bradford et al. 1992; Bradford & Gordon 1992;
Bradford et al. 1994b; Bradford et al. 1994c), pesticide residue (Sparling et al. 2001;
Davidson et al. 2002; Davidson 2004; Fellers et al. 2004), UV exposure (Davidson et al. 2002; Adams et al. 2005) and disease outbreak (Bradford 1991; Fellers et al. 2001;
Vredenburg & Summers 2001; Rachowicz 2002; Rachowicz & Vredenburg 2004;
25 Knapp & Morgan 2006; Rachowicz et al. 2006); but, as previously noted, to date there has not been a cause-and-effect relationship established between any of these indirect factors and the original decline in R. muscosa populations, largely because contemporaneous studies are lacking.
Despite the long history of fish stocking in the Sierra, the sudden decline in R. muscosa populations in Sequoia National Park was not observed until after the harsh winters of 1977-1978 and 1978-1979 (Bradford 1983, 1991); so fish, which had been present for over 100 years at that time, were not considered to be a major component of the decline by some (e.g., Drost & Fellers 1996). However, research into the impact that introduced fish stocking has had on this species has established a direct link between fish stocking and the continuing decline and isolation of local R. muscosa populations (Knapp & Matthews 1998; Matthews & Knapp 1999; Knapp &
Matthews 2000; Knapp et al. 2001b; Matthews et al. 2002; Vredenburg 2004; Knapp
2005). The only meaningful test of a proposed decline factor is to remove the factor suspected of causing a decline and see if populations recover (Caughley 1994), which, unlike for the proposed indirect landscape level factors, has been done for fish stocking by removal, via gill netting, of non-native fish from high-elevation lakes in the Sierra. The results are clear that when fish are removed from lakes and drainages,
R. muscosa populations rebound and abandoned habitats are recolonized by frogs as long as there are donor populations within the dispersal range of R. muscosa (Knapp
& Matthews 1998; Matthews & Pope 1999; Knapp et al. 2001b; Pope & Matthews
2001; Knapp 2002; Vredenburg 2004). Thus, research into this proximate decline factor has resulted in clear management guidelines, namely the removal of fish, for
26 the protection and restoration of aquatic ecosystems in the Sierra that directly benefit
R. muscosa populations (Knapp 2002).
It should be clear from the evidence presented thus far that the dramatic decline of local R. muscosa populations in the late 1970’s (Bradford 1983, 1989,
1991; Bradford et al. 1994b) probably did not result from fish stocking alone. Fish stocking did, however, play a pivotal role in the decline of this species by reducing the density and number of local R. muscosa populations over a much longer period of time resulting in isolation of the remaining populations such that a stochastic event, which in this case seems to have been an unusually high winter precipitation and possibly a disease outbreak, could have had a devastating impact on the remaining small isolated populations (see, Lande & Orzack 1988; Hanski & Gilpin 1991;
Sjogren 1991; Simberloff 1994; Hanski et al. 1996; Hanski & Ovaskainen 2002).
Further, the introduced fish tended to displace R. muscosa populations into marginal habitats such as shallower lakes that are more likely to freeze in the winter and/or more isolated headwater lakes and streams that fish are unable to colonize (Bradford
1989; Bradford et al. 1993; Knapp & Matthews 1998; Knapp & Matthews 2000).
Thus, R. muscosa populations were restricted by fish not to smaller areas of preferred habitat, but rather to habitat that best isolated them from fish (Caughley 1994). These small isolated water bodies are more susceptible to freezing during harsh winters and other stochastic events; or in other words, fish effectively “perched” local frog populations for an extinction event due to harsh winter conditions and/or other stochastic events. Then, once the harsh winters of 1977-1978 and 1978-1979 did occur, R. muscosa populations crashed, but the negative impacts of introduced fish
27 did not end with the sudden population decline. Once winter conditions returned to
“normal,” frog populations failed to rebound, in part, because the proximate effect of fish stocking restricted frog populations to suboptimal environments and prevented recolonization of vacated habitat, thereby placing the remaining small isolated R. muscosa populations at even greater risk of stochastic events.
In this case, the stocking of non-native fish in the Sierra would appear to be not only a proximate decline factor, but also the initial factor that sent this species on a path toward extinction; so research into this proximate decline factor has likely uncovered a major component of the original decline, and more importantly provides land managers with a direct way to improve habitat conditions for frogs, namely by eliminating fish stocking in drainages containing frogs and actively removing the remaining fish from these drainages thereby allowing the aquatic ecosystem and R. muscosa populations to recover (Knapp & Matthews 1998; Armstrong & Knapp
2004; Vredenburg 2004). This is not to suggest that fish removal is an easy task, but it is considerably easer to eliminate fish from selective drainages than it is to stop an emerging disease outbreak, global warming or even pesticide deposition. The latter two factors will likely take several decades to be even partly reversed, and worse still they must be dealt with largely in the political arena long before even partial remediation can realistically begin (Sarkar 1996), which puts these factors well outside the purview of Sierra Nevada land managers.
There are a number of studies that have documented a recent outbreak of the disease chytridiomycosis, caused by the fungal pathogen Batrachytrium dendrobatidis, among R. muscosa populations, particularly in the southern Sierra
28 (Fellers et al. 2001; Vredenburg & Summers 2001; Rachowicz 2002; Rachowicz &
Vredenburg 2004; Briggs et al. 2005; Rachowicz et al. 2005; Knapp & Morgan 2006;
Rachowicz et al. 2006). This disease was discovered very recently (Berger et al.
1998), but chytridiomycosis has been implicated in the recent declines of a number of
amphibian species around the globe (Berger et al. 1998; Daszak et al. 1999; Bosch et
al. 2001; Green & Kagarise Sherman 2001; Young et al. 2001; Green et al. 2002;
Davidson et al. 2003; Lane et al. 2003; Lips et al. 2003; Martinez-Solano et al. 2003;
Muths et al. 2003; Ron et al. 2003; Burrowes et al. 2004; Hanselmann et al. 2004;
Weldon et al. 2004; Briggs et al. 2005; Bull 2005). Initially it was thought that the
reported chytrid disease outbreaks were the result of a novel pathogen being
introduced into the environment causing “extinction waves” in amphibian
populations as the disease was spread globally by introduced species such as other
amphibians and fish (Laurance et al. 1996; Berger et al. 1998; Daszak et al. 1999;
Gillespie & Hero 1999; Lips 1999; Longcore et al. 1999; Gillespie 2001; Weldon
2002; Daszak et al. 2003; Lips et al. 2003; Daszak et al. 2004; Hanselmann et al.
2004; Lips et al. 2004; Weldon et al. 2004; Rachowicz et al. 2006). There is, however, growing evidence to suggest that chytridiomycosis is an emerging infectious disease brought about by an endemic pathogen that has become more virulent due to changing environmental conditions rather than a novel pathogen that has been widely dispersed over a short period of time (Daszak et al. 1999; Carey &
Alexander 2003; Carey et al. 2003; Daszak et al. 2003; Weldon et al. 2004; Briggs et
al. 2005; Rachowicz et al. 2005; Pounds et al. 2006; Rachowicz et al. 2006;
Morehouse et al. 2003). Surveys of preserved museum specimens have found
29 Batrachytrium dendrobatidis infections of specimens collected as far back as 1938 in
Africa and at least as far back as the 1960s in North America suggesting that chytridiomycosis is not a new disease (Weldon et al. 2004; Ouellet et al. 2005) and was present in the environment well before the pulse of amphibian species declines occurred in the late 1970s and early 1980s. There have also been a number of landscape level disease outbreaks reported among amphibian populations in the past, but all of these populations recovered from the stochastic disease outbreak (Emerson
& Norris 1905; Reichenbach-Klinke & Elkan 1965; Pechmann & Wilbur 1994; and sources cited therein). From these examples it should be clear that the chytrid disease outbreak should be considered a natural part of amphibian population biology, but this proximate disease outbreak may be the result of changing environmental conditions, which needs further study. However, the only functional difference between historical disease outbreaks and the proximate event is that the R. muscosa populations being affected today are small and isolated due to the effects of introduced fish stocking, a condition which is well known to increase the effect of stochastic events such as disease outbreak (May 1973; Roughgarden 1975; Shaffer
1981; Hanski 1989), and in habitats where fish have been removed, R. muscosa populations are recovering even when individuals in the populations are infected with chytridiomycosis (Boiano 2008; Maurer & Thompson 2008). Thus, it would appear the best way to protect amphibian species from stochastic events such as a disease outbreak or severe weather conditions, is to reverse the process of habitat degradation, loss and fragmentation, thereby promoting larger amphibian populations and thus greater genetic diversity as well as greater connectivity between local
30 populations, which in turn will help buffer local populations against extinction (see,
Shaffer 1981; Hanski et al. 1996).
The Decline of the Yosemite Toad
The Yosemite toad (Bufo canorus) also appears to have suffered a severe decline in the Sierra Nevada that began in the late 1970s and has continued to the present. The first indication that B. canorus might have suffered a decline was provided by Cynthia Kagarise Sherman (1980; see also Kagarise Sherman & Morton
1984; Kagarise Sherman & Morton 1993; Green & Kagarise Sherman 2001) who reported finding 27 male and 19 female B. canorus adults dead or moribund from an apparent “red leg” disease epidemic at her Tioga Pass meadow (TPM), Mono Co., research site in 1976 through 1978. She also reported finding two additional dead individuals at Saddlebag Lake, Mono Co., in 1977. Although no skin cultures or pathological examination of the toads were performed at the time, the appearance of the “red leg” symptom was generally thought to be the result of septicemia brought about by an Aeromonas hydrophila infection (see Emerson & Norris 1905; Dusi
1949; Hunsaker & Potter 1960; Reichenbach-Klinke & Elkan 1965); but a number of other etiological agents can present the same “red-leg” symptom in amphibians (e.g.
Glorioso et al. 1974; Shotts 1984; Green & Kagarise Sherman 2001), so the actual cause of death was undetermined at the time.
This apparent disease outbreak was preceded by record low snow pack in
1975-1976 and 1976-1977 (Figure 1), which resulted in high larval mortality
31 (reduced recruitment) due to early pool drying during these two years. This apparent
drought was followed in 1977-1978 and 1978-1979 by a much deeper than average
snow pack, which may have decreased adult toad over-winter survival rates due to the
increased hibernation period. Thus, the high variation in snow pack may have caused
or contributed to the conditions necessary for the observed “red-leg” disease
epidemic and ultimately to the local population decline (Kagarise Sherman 1980;
Kagarise Sherman & Morton 1984).
A subsequent histological examination in 2000 of 12 of the dead and
moribund B. canorus specimens collected and preserved in 1976-1979 by Kagarise
Sherman at TPM revealed that four of the individuals died of infectious diseases
including chytridiomycosis of the skin (n = 1), bacillary septicemia (n = 2), and a
combination of the two diseases (n = 1). Five of the specimens were found to be
infected by a variety of diseases (mostly parasitic) with unknown significance, but no
indication of disease or a cause of death could be determined for five of the
specimens (Green & Kagarise Sherman 2001). The absence of a single predominant
infectious disease being found in the toads from TPM, as has been reported in other
amphibian populations suffering decline from an apparent disease outbreak
(Worthylake & Hovingh 1989; Berger et al. 1998; Lips et al. 2003), could indicate
that the histological examination failed to detect the etiological agent(s), such as a
virus or toxicant; or it could suggest that the toads were suffering from immune
system suppression resulting in secondary opportunistic infections (Green & Kagarise
Sherman 2001; see also Glorioso et al. 1974; Hird et al. 1981; Shotts 1984; Carey
1993; Carey et al. 1999; Carey 2000), which could have been brought about by the
32 aforementioned undetected etiological agent(s) (e.g. a virus (Cunningham et al. 1996;
Griffin 1997), a toxicant (Taylor et al. 1999) or global environmental change (Carey
1993; Carey 2000; Carey et al. 2001; Carey & Alexander 2003)). In any case, the
cause of the apparent disease outbreak at TPM remains unclear.
Regardless of the initial cause of the apparent disease outbreak, the resulting
adult mortality in combination with the increased larval mortality in 1976 and 1977
contributed to or directly resulted in the observed local population decline at TPM
that began in the late 1970s and continued through the 1980s. From 1974-1978 the
mean number of male B. canorus entering the breeding population at TPM was 257.5
(± 83.1) individuals. However, in 1979 the number of males entering the TPM study pools dropped to 75, and by 1982 only 28 males were found in the study pools, which constitutes a nine-fold decline from the 1974-1978 mean. Periodic checks of the
TPM pools from 1983-1988 revealed that the male population continued to decline with only 2-4 males being found in the study pools in any given year, and no adult males were observed in the pools during the 1989 season (Kagarise Sherman 1980;
Kagarise Sherman & Morton 1993). In 1990 two adult male B. canorus were again
found in the TPM pools, and the male breeding population at TPM remained at 2-3
individuals through 1994 (Martin 1991a, b; Kagarise Sherman & Morton 1993 and
pers. obs.). The number of female B. canorus entering the TPM breeding pools from
1974 to 1982 varied between 45 and 100 individuals each season; but unlike in the male population, no decline in the female breeding population was observed until
1983 through 1986 when the number of breeding individuals declined sharply to less than four and spawning became sporadic (Kagarise Sherman 1980; Kagarise Sherman
33 & Morton 1993, 1984). From 1987 to 1989 no female B. canorus or signs of reproduction were observed in the TPM pools; but as was the case for male toads, a few female toads and egg masses were once again observed in the TPM pools starting in 1990. Unfortunately, none of the tadpoles produced from 1990 through 1993 survived long enough to reach metamorphosis (Kagarise Sherman 1980; Morton
1982; Martin 1991b, a; Kagarise Sherman & Morton 1993, pers. obs.), but during the
1994 season a few larval toads were able to complete metamorphosis and recruit to the subadult population (pers. obs.).
Clearly B. canorus suffered a severe local population decline at TPM and probably in the surrounding area, but there was little information available regarding the presence or extent of population declines in other parts of the range of B. canorus
before 1990. A few researchers (L. Cory, R. Hansen, A. McCready, M. Morton, pers.
comm.; pers obs; Wake 1990; Jennings & Hayes 1994) observed local population
declines in other parts of the range of B. canorus in the late 1970s and early 1980s;
but there was little communication between the independent researchers about the
decline of their study populations, resulting in a lack of realization that B. canorus
populations were declining throughout their range. In fact, Kagarise Sherman and
Morton thought the local population decline they observed at TPM might have been
an unintended consequence of their research methodology and thus, a local decline
only that would rebound after their intensive research ended in 1980 (M. Morton,
pers. comm.; Kagarise Sherman & Morton 1993). Further, Kagarise Sherman and
Morton were the only researchers studying the population demographics of B.
canorus in the late 1970s, so the scope and severity of the decline of B. canorus was
34 largely unappreciated by researchers until 1990 when their anecdotal observations of
declines in local populations of B. canorus, and R. muscosa, were combined and
presented at the GAD workshop by Bradford (pers. notes from workshop). These
observations were subsequently used in the GAD workshop report of findings as
evidence for an enigmatic amphibian decline in high-elevation “protected” habitats
(Blaustein & Wake 1990; Wake & Morowitz 1990; pers obs).
Since the GAD workshop, several research teams have studied the extent of
the decline of B. canorus by resurveying sites known to have supported B. canorus populations before 1980 (Martin 1990, 1991a; Kagarise Sherman & Morton 1993;
Jennings & Hayes 1994; Drost & Fellers 1996) and by conducting random surveys for B. canorus populations throughout their range in the Sierra (Bradford & Gordon
1992; Martin et al. 1993; Martin 1994; Stebbins & Cohen 1995; Brown 2002; pers. comm.). All of these researchers found that B. canorus populations were absent from about half of the sites where they were known to occur in the past or where it was expected they should occur; and when B. canorus were found, they were generally found in very small populations, which supports the contention that this species has suffered a landscape level decline.
However, none of these population surveys or studies regarding the indirect decline factors discussed above, has found obvious reasons for the apparent decline of this species. In short, the anecdotal decline of B. canorus was used as evidence for the hypothesized GAD occurring in “pristine” habitats, and subsequent survey efforts suggest that B. canorus has indeed suffered a precipitous decline; but, as discussed above, the habitat in the Sierra Nevada can hardly be considered pristine. Therefore,
35 a fundamental assumption of the GAD hypothesis, namely that amphibian population
declines have occurred in “pristine” habitat, needs to be re-examined. Further, the
fundamental question for research into the decline of B. canorus should not be, “What
indirect global factors caused population declines in B. canorus back in the late
1970s?” but rather the fundamental research question should be, “What factors, direct
or indirect, are currently impeding or preventing the recovery of local B. canorus populations?” Once the factors currently affecting populations have been determined, one should ask how these proximate factors can be ameliorated to promote local population recovery and what the historical significance of these proximate factors may have been.
36 STUDY ANIMAL
Description
The Yosemite toad, Bufo canorus (Camp 1916), demonstrates a striking degree of sexual dimorphism in which the larger females have a mottling of black patches on a grayish-white to light-tan ground color and the smaller adult males exhibit a uniform coloration of olive-green to lemon-yellow (Stebbins 1951; Oliver
1955). The differences in coloration between the sexes has been described as the
“most pronounced instance of sexual dichromism among North American anurans”
(Stebbins 1951, p. 246) and may be an adaptation for survival in a high elevation environment (Karlstrom 1962).
A recent study by Shaffer, Fellers et al. (2000) found limited support for the monophyly of B. canorus based on a single-strand conformation polymorphism analysis of 372 individuals from 28 locations clustered in Yosemite and Kings
Canyon National Parks. Subsequent analysis by Magee (pers. comm.) has suggested that the northern and southern populations of B. canorus are more closely related to
B. boreas halophilus and B. B. boreas populations, respectively, than they are to each other, which suggests B. canorus may not be monophyletic with respect to B. boreas.
However, both of these studies have limited sample sizes from restricted areas, and
neither study takes into account secondary hybridization with B. boreas, which
appears to be occurring with greater frequency (particularly at the edges of the range,
e.g. the 6 Kings Canyon NP sites sampled) as weather patterns in the Sierra change,
resulting in altered distribution of the two species and greater contact between them
37 (pers. obs.). Until such time as more extensive work can be completed, Shaffer,
Fellers et al. (2000) suggest B. canorus should continue to be recognized as a distinct species. Another very recent paper (Frost et al. 2006) has proposed sweeping changes to amphibian taxonomy including placing the (Bufo) boreas group of toads, which includes B. canorus, in the genus Anaxyrus. Since the Frost et al. paper will require general acceptance before its proposed changes can be adopted, this paper will continue to refer to the Yosemite toad as Bufo canorus.
Range
This montane toad is endemic to the Sierra Nevada Mountains of California from the Blue Lakes region of Alpine County in the north (Karlstrom 1962) to south of Evolution Lake in Fresno County (Karlstrom 1962; Stebbins 1966). The west and east range limits of B. canorus are generally restricted by elevation at about 2,133 m and 2,438 m, respectively, with the higher elevational limit on the eastern slope of the
Sierra resulting from its steeper escarpment (Karlstrom 1962) and “rain shadow” effect (Grinnell & Storer 1924; Storer & Usinger 1963). Karlstrom (1962) gives the maximum known altitudinal range limits of B. canorus as 1,950 m (Aspen Valley,
YNP, Tuolumne Co.) to 3,444 m (Mt. Dana, YNP, Tuolumne Co.), but he suggests the majority of locality records should fall within the elevational range of about 2,591 m to 3,048 m as the habitats both above and below this elevational range are only marginally suitable. This gives B. canorus the most restricted distribution of any endemic Sierra Nevada anuran.
38
Habitat
Within this limited range, Grinnell and Camp (1917) state that B. canorus occupies the Lodgepole Pine-Red Fir Belt (aka Canadian Life Zone, ~1,829-2,438 m) and Subalpine Belt ( aka Hudsonian Life Zone, ~2,438-3,200 m), and can even extend into the Alpine Belt (aka Alpine-Arctic Life Zone, >3,200 m). Karlstrom’s
(1962) elevational observations suggest, however, that the majority of B. canorus populations should be found within the Subalpine Belt, which is characterized by sparse forests of lodgepole pine (Pinus contorta var. murrayana), mountain hemlock
(Tsuga mertensiana) and whitebark pine (Pinus albicaulis) (Grinnell & Storer 1924;
Storer & Usinger 1963).
The climate of the Subalpine Belt in the High Sierra varies considerably across years, seasons and even within a given day. Precipitation, for example, fluctuates significantly by season with more than half of annual precipitation falling as snow during January, February and March. Less than 3% of total annual precipitation falls in the summer, usually as rain during brief afternoon thunderstorms, but hail and even snow flurries are not uncommon. The temperature range in the high Sierra is reported to be between -34º and +38º C with the coldest temperatures occurring in the winter, but summer night time temperatures can frequently drop below freezing (Storer & Usinger 1963). Given such high climatic variability, it is easy to understand why B. canorus is reported to spend seven to eight months or more in hibernacula during the long Sierran winter, and why in the summer
39 this toad is reported to be active only during the day (Grinnell & Storer 1924; Storer
1925; Stebbins 1951; Mullally 1953; Wright & Wright 1949; Wright & Wright 1933).
There are, however, a few records of B. canorus being active for a few hours after
sunset during breeding congregations (Grinnell & Storer 1924; Storer 1925; Mullally
& Cunningham 1956; Karlstrom 1962), but more work is needed to determine the
extent of nocturnal activity by this toad.
Bufo canorus is generally thought to prefer the relatively open wet meadows,
which resemble tundra, that are scattered throughout the Sierra and are usually
associated with alpine lakes or streams (Camp 1916; Grinnell & Storer 1924;
Mullally 1953; Karlstrom 1962). Within these montane meadows, adult B. canorus
are reported to be common along the margins of lakes, shallow runoff streams and
ephemeral pools where these toads are known to breed, as well as in close association
with water where the meadow vegetation is generally deeper or more luxuriant than
usual or where there are patches of low willows which are used by the toads for cover
(Grinnell & Camp 1917; Grinnell & Storer 1924; Mullally 1953; Mullally &
Cunningham 1956; Karlstrom 1962). In addition to willows, B. canorus is also known to seek cover under surface objects such as logs and stones, but their preferred cover in meadows appears to be the vacated subterranean burrows of rodents such as meadow mice (Microtus montanus) and pocket gophers (Thomomys monticola).
These burrows are thought to provide protection from the cold temperatures at night in the high Sierra, as well as a moist microclimate during the day which allows toads to inhabit the drier parts of the meadow away from open water (Stebbins 1951;
Mullally 1953; Mullally & Cunningham 1956; Karlstrom 1962; see also Schwarzkopf
40 & Alford 1996). Stebbins (1951) points out that the meadow habitats B. canorus seem to prefer are generally surrounded by dry rocky terrain that this toad rarely, if ever, inhabits. Thus, the hot dry terrain surrounding the meadows would appear to restrict overland movements by diurnal toads, likely isolating breeding populations in most years, thereby promoting local population differentiation (Stebbins 1951) and breeding site fidelity. There are, however, several reports of B. canorus being found many meters away from meadows on the steeply sloping mountainsides where the vegetation is unusually rich or in bushy willow (Salix sp.) thickets that often concentrate beside ephemeral watercourses or seepages (Mullally 1953; Mullally &
Cunningham 1956; Karlstrom 1962; Kagarise Sherman 1980). Kagarise Sherman
(1980), in particular, reports adult toads traversing distances of 150-230 m upslope to reach foraging habitat and hibernacula at the bases of willows (and consequently navigate the return trip each spring over snow drifts). Also, Morton (1981) reports finding several female B. canorus early in the active season, who had presumably just emerged from their hibernacula, 750 m from the closest major breeding site at the edge of a talus slope (near willows, pers. comm.), which was predominantly covered with snow at the time. (The location of this particular overwintering site is also suggested by Mullally & Cunningham 1956; Kagarise Sherman & Morton 1984.)
Thus, it is clear that B. canorus are capable of traveling relatively long distances from the wet meadows and permanent sources of water over relatively hostile terrain; but many questions remain unanswered, such as when these toads migrate between habitat patches, how they avoid desiccation traversing the upland slopes, how they locate suitable foraging habitat and hibernacula (which are capable of protecting the
41 toads from freezing under several meters of snow and ice during the eight-month long winter), and what habitat features are important for identifying suitable toad habitat.
42 STUDY AREA
Highland Lakes
This study was conducted within a large meadow complex located in the
northern Sierra Nevada Mountains of California. The meadow complex studied,
Highland Lakes, is on Stanislaus National Forest (NF), Alpine County, 5.9 km south
of Ebbett’s Pass on State Highway 4. This region is a glacial cut valley, with a
northeast to southwest aspect that appears to have been formed by the erosion of the
headwall between two glacial cirques. The paired kettles, named Highland Lakes, are
the headwaters of two different drainage basins separated by a moraine, with the
larger northern lake draining into the Mokelumne River Basin, and the southern lake
draining into the Stanislaus River Basin. The substrate within this valley is
predominately granitic till with thin peat soil development on the valley floor. There
are eleven large meadows within the Highland Lakes Meadow Complex (HLMC)
where B. canorus have been found, and many of these meadows supported breeding
populations in the past; but breeding congregations only occurred in six of the
meadows in 1994 (pers. obs.). For this study, I focused on three primary meadows
containing pools that have been used consistently by B. canorus for reproduction since at least the 1960s (McCreedy pers. comm., pers. obs.).
43 North Pools
The first primary study meadow, which I call north pools, is located northeast of the northern lake downstream from the lake out-flow (38.495° N, 119.797°W,
2,619 m). North pools is a wet Nebraska Sedge class meadow (Ratliff 1982), but its hydrology is difficult to characterize as it is located below the north lake rock dam, which was built to enlarge the natural lake in 1952 (Albright et al. 1994) and appears to have altered the stream flow through the meadow. Based on the topography of the meadow, the three breeding ponds appear to be located in the abandoned stream channel that eventually confluents with the active stream channel (likely a second order stream), the North Fork of the Mokelumne River. The main stream channel banks are severely eroded along approximately 10 meters of its length to the east of the north ponds, but the banks are stabilized downstream by low growing willows, and the channel becomes incised with a couple of small erosional head-cuts located farther down stream within the meadow. The breeding pools are shallow (< 0.5 m deep), typically ephemeral pools that vary considerably in depth and area depending on snow-melt sheet-flows early in the season, the water table of the meadow and precipitation recharge late in the season, as there is no direct stream channel inflow to the pools at this time. Thus, the longevity of the pools is dependent in large part on the depth of annual snow pack in the surrounding area (Figure 2) and the variation in the water table of the meadow. The littoral zone of the pools, much like the rest of the meadow, is a dense sod of predominately Nebraska sedge (Carex nebraskensis), which is considered a valuable late season forage for cattle (Ratliff 1982); and it has
44 been and continues to be subject to grazing by cattle (see details below). The north
pools meadow at one time supported one of the largest breeding populations of B.
canorus in the northern Sierra (McCreedy, pers. comm., pers. obs.).
Mid Pools
The second primary study meadow in the HLMC that contains breeding
ponds, which I call mid ponds (38.490° N, 119.803° W, 2,620 m), is located between
the two Highland Lakes north of the moraine, so it is still contained within the
Mokelumne River Basin. Mid ponds meadow is also classified as a Nebraska sedge
meadow (Ratliff 1982), but it contains a series of five small ponds located adjacent to
a spring/snow fed first order stream that flows into the northern lake on the southeast
side of the meadow. The ponds themselves do not directly communicate with the
stream channel, but rather they receive their water inflow from snow-melt sheet-flows
early in the season, the water table of the meadow and from precipitation recharging
late in the season much like the north pools; but the mid pools have undercut banks
making them appear to be of kettle origin. However, the mid pools meadow is much
different from north pools meadow as it has a sunken basin within it that appears
similar to a bog meadow early in the season. The vernal pool that forms in this
sunken basin usually dries up well before the end of July, but it supported breeding
and maturation of tadpoles up until 1989 (pers. obs.) and supported a very large
breeding population of B. canorus in the 1960s (McCreedy, pers. comm.). The littoral zone vegetation of the five breeding ponds in mid pools meadow are
45 predominately comprised of Nebraska sedge, but rushes (Juncus sp.) are common in
and around the pools; and this meadow also supports swamp onions (Allium validum)
and mosses, which are likely present due to the increased moisture in the meadow. A
large band of corn lilies (Veratrum californicum) is located on the southwest side of the meadow. There is also a dense willow thicket (likely alpine, Salix petrophila)
located on the moraine slope south of the meadow. The most striking feature of this
meadow is the severe erosion that has occurred along the stream banks resulting in
down cutting of the stream channel of a meter or more; and like north pools meadow,
this meadow has been extensively grazed by cattle in the past (see details below).
Tryon Meadow
Tryon Meadow (38.505° N, 119.801° W, 2,567 m), the third HLMC primary
study site, is located 1.2 km north of north pools meadow at the confluence of two
spring fed first order streams that in turn flow into the Mokelumne River. Tryon
meadow is in hydrologic transition due to the severe down cutting of the stream
channels running through the meadow. There were approximately six ephemeral
pools within the meadow that supported B. canorus spawning before 1990 (pers. obs.)
and very large breeding congregations of perhaps 24 pairs at one pond in 1974
(McCreedy pers. comm.), but currently there are only three pools within Tryon
Meadow supporting B. canorus spawning. The first is a bathtub watering trough
sunk into the ground on the southwestern edge of the meadow near the Wooster
family barn, with very little associated vegetation. I have observed B. canorus
46 depositing egg masses in and around this trough, but I have never observed any of
these tadpoles surviving more than a few weeks or surviving to metamorphosis. The
second ephemeral pool is located in the middle of a Nebraska sedge meadow in the
southeast corner of Tryon meadow. There has been consistent spawning by B.
canorus in this pool for many years, but the pool has not persisted long enough for tadpole maturation since at least 1990. The third pool is an off channel pool (~2 m diameter) supporting littoral zone rushes (Juncus sp.) located on the northeastern
edge of the meadow near the Tryon family barn and cabin, which is used as a summer
“swimming hole” by children playing in the meadow. This pool is relatively
permanent due to its close association with the stream channel, and it does support a
small amount of reproduction and tadpole maturation in most years. It was the only
location in Tryon meadow where B. canorus tadpoles successfully metamorphosed in
1994. Much of Tryon meadow supports dense thickets of several willow species
(including lemon, Salix lemmonii; Sierra, S. commutat and silver willow, S.
geyeriana) and Nebraska sedge class meadow patches; but there has been a recent
expansion of corn lilies within the meadow since 1990, which is generally thought to
be an indication of overgrazing (Menke et al. 1996). Tryon meadow has been
entirely fenced for many years now to exclude cattle for much of the season because
this pasture is grazed by the Wooster family horses used to wrangle cattle on the
Highland Lakes Grazing Allotment and as a late season gathering pasture for cattle
(Albright et al. 1994).
47 Highland Lakes Grazing History
The HLMC has been extensively grazed for about three months almost every summer since the 1860s. Initially, the Highland Lakes Allotment was grazed by at least 1,800 sheep and about 200 cows and horses; but by 1944 sheep were no longer permitted on the allotment, which may have been due in part to an outbreak of hoof- and-mouth disease in the late 1920s that resulted in the destruction of the sheep flocks which were grazed in much of the eastern Sierra (Albright et al. 1994; Menke et al.
1996). With the exception of the 1995 season and possibly a few years during or immediately following World War II, the family of the current permittee, the
Woosters, have grazed the Highland Lakes Allotment (and thus the north pools, mid pools and Tryon meadows) every summer since 1941 with varying numbers of horses and about 215 cow-calf pairs (records of actual numbers are sparse) (Albright et al.
1994).
In more recent years Stanislaus NF biologists have conducted periodic condition and trend analyses of the Highland Lakes Grazing Allotment. One such analysis conducted in 1989 gave “unsatisfactory condition” scores for north pools, mid pools and Tryon meadows. These range analyses consist of vegetation and soil scores that are given as one of four classes (E=excellent; G=good; F=fair; and
P=poor) followed by a trend sign of “↑” for upward; “→” for stable; or “↓” for a downward condition trend. Scores of fair with an upward trend or higher indicate a
“satisfactory” condition, whereas scores of fair with a stable trend or lower are considered “unsatisfactory” (Albright et al. 1994). Range condition and trend
48 analysis scores for mid pools meadow and Tryon meadow taken during the summer of 1991 were Fair↓/Poor↓, and F→/P↓ respectively (Wold, pers. comm., provided to the Public Involvement Field Trip participants on 6 September 1991). These unsatisfactory condition scores are not unique in the Highland Lakes Allotment. Out of a total of 20 vegetation and soil condition analysis scores for areas in the Highland
Lakes Allotment provided by Stanislaus NF in 1991 (Wold, pers. comm.), only two of the area scores could be considered “satisfactory”, and only one area could be considered borderline satisfactory. Albright et al. (1994, table R-2, p. 15) reported that 526 of 583 recently surveyed primary range areas within the Highland Lakes
Grazing Allotment fell into the “unsatisfactory” condition category, indicating that
90% of the primary range in the Highland Lakes Allotment has been overgrazed.
This conclusion should not be considered surprising in light of Calaveras Ranger
District range utilization records indicating that the permittee has “exceeded allowable use” in the key areas of the Highland Lakes allotment throughout much of the 1970s, and has used the range “in excess of allowable use” every year from 1987 through 1994 (there are few records from the 1980s) (Albright et al. 1994). The
Stanislaus NF Land and Resources Management Plan (LMP IV-65) approved in 1991 calls for a minimum stubble height of 4 inches (or ~10 cm) at the end of the grazing season, which is significantly less than the 25-100 cm height that un-grazed Nebraska sedge can reach in the Sierra (Jepson 1975); but the consistent over-utilization of the
Highland Lakes Allotment has left very little meadow vegetation at the end of each season. As a result of this over-utilization of the range, the 1995 Allotment
Management Plan, which was approved by the Stanislaus NF Supervisor, called for a
49 gradual cattle “reduction” from 215 calf-cow pairs (or 645 Animal Months) in 1996 to 140 pairs (420 Animal Months) by 2001 unless “…the grazing capacity estimate is revised upward through monitoring...” and called for the implementation of a three- pasture rest rotation system where each meadow in the allotment would only be grazed two out of every three years (Wold 1995). The original intent of my study was to analyze the effectiveness of the proposed rest rotation management action for improving amphibian habitat condition within the HLMC. However, the rest rotation management action was never implemented by Stanislaus NF on the Highland Lakes
Allotment, and no grazing occurred on the Highland Lakes allotment during the 1995 season due to the ~180% of average snow fall (Figure 2) pushing back the “on time” or grazing start date. Thus, the entire Highland Lakes Grazing Allotment was effectively “rested” for the 1995 season, but grazing resumed in 1996.
50 RESEARCH DIRECTION
The ultimate goal of research into the GAD problem is (or should be) to
identify the factors impacting amphibian populations, eliminate these population
and/or landscape level impacts or at least mitigate them and thereby reverse the
observed population declines; or in short, the goal is to develop a biologically based
recovery plan for declining amphibian species. We know that local populations of a
high-elevation Sierra Nevada endemic amphibian, B. canorus, have declined or
become extinct throughout its range. The apparent decline of this species was used as
evidence during the GAD workshop for a global enigmatic amphibian decline in
“protected” or “pristine” habitats. I have argued that the Sierra Nevada ecosystem is
far from “pristine” and that anthropocentric habitat degradation and destruction have
occurred throughout the range of B. canorus. Another high-elevation Sierra Nevada amphibian species, R. muscosa, also suffered a severe decline throughout its range, and was also used as evidence for an enigmatic decline during the GAD workshop.
However, it is now clear that R. muscosa was being severely impacted by the
introduction of non-native predatory fish species into the Sierra well before the
extinction pulse in the late 1970s. We know from the original GAD workshop report
and subsequent research that the vast majority of observed amphibian declines are the
result of anthropocentric habitat destruction, so the decline of these species should
come as no surprise once we accept the idea that they do not occur in “protected” or
“pristine” habitats, but unlike for R. muscosa, research into the decline of B. canorus
has thus far failed to reveal clear factors impacting populations.
51 Unfortunately, research into the factors affecting amphibian populations are often hampered by a lack of basic ecological data regarding the species in question.
Many of the ecological studies conducted on amphibians thus far have focused primarily on the breeding congregations, which are relatively easy to locate, especially for largely aquatic species such as R. muscosa. However, often very little data are available for more terrestrial species such as B. canorus regarding adult movement patterns, terrestrial habitat utilization and basic population ecology owing to the difficulty in locating terrestrial amphibians outside of their breeding pools
(Beebee 1996; Alford & Richards 1999; Semlitsch 2000, 2002; Calhoun et al. 2003).
This information gap often results in a rather contentious debate among scientists and land managers as to the best way to protect the remaining amphibian populations.
The most basic question as to what habitat should be protected is impossible to answer without some understanding as to how individuals are distributed within the environment and how they utilize the available habitat. For example, without knowing what habitat an amphibian species uses during its terrestrial stage, it is impossible to identify its core habitat needs and thus, it is also impossible to identify the impacts of management decisions on core terrestrial habitats utilized by amphibians (Semlitsch 2000; Knight 2001; Semlitsch 2003b; Norris 2004). Further, as previously discussed, there are very few data available to directly connect amphibian population changes to environmental perturbations; and for many species, this is due to the lack of basic population demographic information (Pechmann et al.
1991; Pechmann & Wilbur 1994; Alford & Richards 1999; Biek et al. 2002;
Semlitsch & Rothermel 2003; Semlitsch 2003a; Beebee & Griffiths 2005). This lack
52 of population data not only precludes the establishment of cause and effect relationships between proposed decline factors and population demographics that could narrow the scope of mitigation measures in management plans, but also makes it difficult-to-impossible to evaluate the effectiveness of recovery efforts.
The current study attempts to elucidate the basic ecological data missing from one such amphibian species, B. canorus, in an effort to at least partially fill this information gap. The first aspect of this study elucidates the post-reproductive movement patterns of adult B. canorus using radio and string tracking techniques to establish the core habitat needs of this species. The second aspect of this study quantifies the post-reproductive habitat utilized by this species in an effort to more accurately model its habitat needs for use in evaluating the effects of proposed decline factors and management strategies.
53
LITERATURE CITED
Adams, M. J., B. Hossack, R. A. Knapp, P. S. Corn, S. Diamond, P. Trenham, and D.
Fagre. 2005. Distribution patterns of lentic-breeding amphibians in relation to
ultraviolet radiation exposure in western North America. Ecosystems 8:488-
500.
Albright, R., L. Hanson, P. Kaunert, C. Madden, A. Palmer, R. Ruediger, D. Van
Keuren, R. Wetzel, L. Conway, and J. Frazier. 1994. Highland Lakes Term
Permit and Allotment Management Plan, Environmental Assessment. SO-
0592-4. Pages 1-76. Stanislaus National Forest, Sonora, CA.
Alexander, M. A., and J. K. Eischeid. 2001. Climate variability in regions of
amphibian declines. Conservation Biology 15:930-942.
Alford, R. A., and S. J. Richards. 1997. Lack of evidence for epidemic disease as an
agent in the catastrophic decline of Australian rain forest frogs. Conservation
Biology 11:1026-1029.
Alford, R. A., and S. J. Richards. 1999. Global amphibian declines: A problem in
applied ecology. Annual Review of Ecology and Systematics 30:133-165.
Alvarez, L. W., W. Alvarez, F. Asaro, and H. V. Michel. 1980. Extraterrestrial cause
for the Cretaceous-Tertiary extinction. Science 208:1095-1108.
Armour, C. L., D. A. Duff, and W. Elmore. 1991. The effects of livestock grazing on
riparian and stream ecosystems. Fisheries 16:7-11.
Armour, C. L., D. A. Duff, and W. Elmore. 1994. The effects of livestock grazing on
western riparian and stream ecosystems. Fisheries 19:9-12.
54
Armstrong, T. W., and R. A. Knapp. 2004. Response by trout populations in alpine
lakes to an experimental halt to stocking. Canadian Journal of Fisheries and
Aquatic Sciences 61:2025-2037.
Barinaga, M. 1990. Where Have All the Froggies Gone? Science 247:1033-1034.
Beebee, T. J. C. 1992. Amphibian decline? Nature 355:120-120.
Beebee, T. J. C. 1996. Ecology and Conservation of Amphibians. Chapman & Hall,
London.
Beebee, T. J. C., and R. A. Griffiths. 2005. The amphibian decline crisis: A watershed
for conservation biology? Biological Conservation 125:271-285.
Belden, L. K., E. L. Wildy, and A. R. Blaustein. 2000. Growth, survival and behavior
of larval long-toed salamanders (Ambystoma macrodactylum) exposed to
ambient levels of UV-B radiation. Journal of Zoology 251:473-479.
Belsky, A. J., A. Matzke, and S. Uselman. 1999. Survey of livestock influences on
stream and riparian ecosystems in the western United States. Journal of Soil
and Water Conservation 54:419-431.
Berger, L., R. Speare, P. Daszak, D. E. Green, A. A. Cunningham, C. L. Goggin, R.
Slocombe, M. A. Ragan, A. D. Hyatt, K. R. McDonald, H. B. Hines, K. R.
Lips, G. Marantelli, and H. Parkes. 1998. Chytridiomycosis causes amphibian
mortality associated with population declines in the rain forests of Australia
and Central America. Proceedings of the National Academy of Sciences
95:9031-9036.
55
Biek, R., W. C. Funk, B. A. Maxell, and L. S. Mills. 2002. What is missing in
amphibian decline research? Insights from ecological sensitivity analysis.
Conservation Biology 16:728-734.
Blaustein, A. R., and L. K. Belden. 2003. Amphibian defenses against ultraviolet-B
radiation. Evolution & Development 5:89-97.
Blaustein, A. R., L. K. Belden, D. H. Olson, D. M. Green, T. L. Root, and J. M.
Kiesecker. 2001. Amphibian Breeding and Climate Change. Conservation
Biology 15:1804-1809.
Blaustein, A. R., B. Edmond, and J. M. Kiesecker. 1995. Ambient ultraviolet
radiation causes mortality in salamander eggs. Ecological Applications 5:740-
743.
Blaustein, A. R., P. D. Hoffman, D. G. Hokit, J. M. Kiesecker, S. C. Walls, and J. B.
Hays. 1994a. UV repair and resistance to solar UV-B in amphibian eggs - a
link to population declines. Proceedings of the National Academy of Sciences
91:1791-1795.
Blaustein, A. R., P. D. Hoffman, J. M. Kiesecker, and J. B. Hays. 1996. DNA repair
activity and resistance to solar UV-B radiation in eggs of the red-legged frog.
Conservation Biology 10:1398-1402.
Blaustein, A. R., D. G. Hokit, R. K. Ohara, and R. A. Holt. 1994b. Pathogenic fungus
contributes to amphibian losses in the Pacific-Northwest. Biological
Conservation 67:251-254.
Blaustein, A. R., and J. M. Kiesecker. 1997. The significance of ultraviolet-B
radiation to amphibian population declines. Reviews in Toxicology 1:5-6.
56
Blaustein, A. R., J. M. Kiesecker, D. P. Chivers, D. G. Hokit, A. Marco, L. K.
Belden, and A. C. Hatch. 1998. Effects of ultraviolet radiation on amphibians:
field experiments. American Zoologist 38:779-812.
Blaustein, A. R., J. M. Romansic, J. M. Kiesecker, and A. C. Hatch. 2003. Ultraviolet
radiation, toxic chemicals and amphibian population declines. Diversity and
Distributions 9:123-140.
Blaustein, A. R., and D. B. Wake. 1990. Declining amphibian populations: A global
phenomenon? Trends in Ecology & Evolution 5:203-204.
Blaustein, A. R., and D. B. Wake. 1995. The puzzle of declining amphibian
populations. Scientific American 1995:52-57.
Boiano, D. 2008 [abstract]. Ongoing Restoration of Mountain Yellow-legged Frogs
and High Mountain Lakes and Streams in Sequoia and Kings Canyon
National Parks, California. Pages 3-4 in California-Nevada Amphibian
Populations Task Force, San Diego, CA.
Boone, M. D., and R. D. Semlitsch. 2001. Interactions of an insecticide with larval
density and predation in experimental amphibian communities. Conservation
Biology 15:228-238.
Bosch, J., I. Martinez-Solano, and M. Garcia-Paris. 2001. Evidence of a chytrid
fungus infection involved in the decline of the common midwife toad (Alytes
obstetricans) in protected areas of central Spain. Biological Conservation
97:331-337.
Bradford, D. F. 1983. Winterkill, oxygen relations, and energy metabolism of a
submerged dormant amphibian, Rana muscosa. Ecology 64:1171-1183.
57
Bradford, D. F. 1989. Allotropic distribution of native frogs and introduced fishes in
high Sierra Nevada lakes of California: Implication of the negative effect of
fish introductions. Copeia 1989:775-778.
Bradford, D. F. 1991. Mass mortality and extinction in a high-elevation population of
Rana muscosa. Journal of Herpetology 25:174-177.
Bradford, D. F., and M. S. Gordon. 1992. Aquatic Amphibians in the Sierra Nevada:
Current Status and Potential Effects of Acidic Deposition on Populations.
California Air Resources Board, Contract No. A932-139., Sacramento, CA.
Bradford, D. F., M. S. Gordon, D. F. Johnson, R. D. Andrews, and W. B. Jennings.
1994a. Acidic deposition as an unlikely cause for amphibian population
declines in the Sierra-Nevada, California. Biological Conservation 69:155-
161.
Bradford, D. F., D. M. Graber, and F. Tabatabai. 1994b. Population declines on the
native frog, Rana muscosa, in Sequoia and Kings Canyon National Parks,
California. Southwestern Naturalist 39:323-327.
Bradford, D. F., C. Swanson, and M. S. Gordon. 1991. Aquatic Amphibians in the
Sierra Nevada: Current Status and Potential Effects of Acidic Deposition on
Populations. California Air Resources Board, Contract No. A932-139,
Sacramento, CA.
Bradford, D. F., C. Swanson, and M. S. Gordon. 1992. Effects of low pH and
aluminum on two declining species of amphibians in the Sierra-Nevada,
California. Journal of Herpetology 26:369-377.
58
Bradford, D. F., C. Swanson, and M. S. Gordon. 1994c. Effects of low pH and
aluminum on amphibians at high-elevation in the Sierra-Nevada, California.
Canadian Journal of Zoology 72:1272-1279.
Bradford, D. F., F. Tabatabai, and D. M. Graber. 1993. Isolation of remaining
populations of the native frog, Rana muscosa, by introduced fishes in Sequoia
and Kings Canyon National Parks, California. Conservation Biology 7:882-
888.
Bridges, C. M., and M. D. Boone. 2003. The interactive effects of UV-B and
insecticide exposure on tadpole survival, growth and development. Biological
Conservation 113:49-54.
Briggs, C. J., V. T. Vredenburg, R. A. Knapp, and L. J. Rachowicz. 2005.
Investigating the population-level effects of chytridiomycosis, an emerging
infectious disease of amphibians. Ecology 86:3149-3159.
Broomhall, S. D., W. S. Osborne, and R. B. Cunningham. 2000. Comparative effects
of ambient ultraviolet-B radiation on two sympatric species of Australian
frogs. Conservation Biology 14:420-427.
Brown, C. 2002. Population and Habitat Monitoring for the Yosemite Toad: Sierra
Nevada Framework Project. Pages 1-29 +Attachments. USFS, Sacramento,
CA.
Bull, E. L. 2005. Ecology of the Columbia spotted frog in northeastern Oregon.
PNW-GTR-640. Pages 1-46. U.S. Department of Agriculture, Forest Service,
Pacific Northwest Research Station, Portland, OR.
59
Bull, E. L., and M. P. Hayes. 2000. Livestock effects on reproduction of the
Columbia spotted frog. Journal of Range Management 53:291-294.
Burcham, L. T. 1957. California Range Land: An Historical-ecological Study of the
Range Resource of California. Calif. Dept. of Natural Resources, Division of
Forestry, Sacramento, CA.
Burrowes, P. A., R. L. Joglar, and D. E. Green. 2004. Potential causes for amphibian
declines in Puerto Rico. Herpetologica 60:141-154.
Calhoun, A. J. K., T. E. Walls, S. S. Stockwell, and M. McCollough. 2003.
Evaluating vernal pools as a basis for conservation strategies: A Maine case
study. Wetlands 23:70-81.
Camp, C. L. 1916. Description of Bufo canorus, a new toad from the Yosemite
National Park. University of California Publications in Zoology 17:11-14.
Carey, C. 1993. Hypothesis concerning the causes of the disappearance of boreal
toads from the mountains of Colorado. Conservation Biology 7:355-362.
Carey, C. 2000. Infectious disease and worldwide declines of amphibian populations,
with comments on emerging diseases in coral reef organisms and in humans.
Environmental Health Perspectives 108:143-150.
Carey, C., and M. A. Alexander. 2003. Climate change and amphibian declines: is
there a link? Diversity and Distributions 9:111-121.
Carey, C., D. F. Bradford, J. L. Brunner, J. P. Collins, E. W. Davidson, J. E.
Longcore, M. Ouellet, A. Pessier, and D. M. Schock. 2003. Biotic factors in
amphibian population declines. Pages 153-208 in G. Lindre, S. K. Krest, and
D. W. Sparling (Eds.). Multiple Stressors and Declining Amphibian
60
Populations. Society for Environmental Toxicology and Chemistry Press,
Pensacola, Florida.
Carey, C., and C. J. Bryant. 1995. Possible interrelations among environmental
toxicants, amphibian development, and decline of amphibian populations.
Environmental Health Perspectives 103:13-17.
Carey, C., N. Cohen, and L. Rollins-Smith. 1999. Amphibian declines: an
immunological perspective. Developmental and Comparative Immunology
23:459-472.
Carey, C., W. R. Heyer, J. Wilkinson, R. A. Alford, J. W. Arntzen, T. Halliday, L.
Hungerford, K. R. Lips, E. M. Middleton, S. A. Orchard, and A. S. Rand.
2001. Amphibian declines and environmental change: Use of remote-sensing
data to identify environmental correlates. Conservation Biology 15:903-913.
Caro, T. M., and G. O'Doherty. 1999. On the use of surrogate species in conservation
biology. Conservation Biology 13:805-814.
Caughley, G. 1994. Directions in conservation biology. The Journal of Animal
Ecology 63:215-244.
Clary, W. P., N. L. Shaw, J. G. Dudley, V. A. Saab, J. W. Kinney, and L. C.
Smithman. 1996. Response of a Depleted Sagebrush Steppe Riparian System
to Grazing Control and Woody Plantings. INT-RP-492. USDA Forest Service.
Cleaveland, S., G. R. Hess, A. P. Dobson, M. K. Laurenson, H. I. McCallum, M. G.
Roberts, and R. Woodroffe. 2002. The role of pathogens in biological
conservation. Pages 139-150 in P. J. Hudson, A. Rizzoli, B. T. Grenfell, H.
61
Heesterbeek, and A. P. Dobson (Eds.). The Ecology of Wildlife Diseases.
Oxford University Press, New York, NY.
Coile, Z. 2004. Yosemite Violates New Federal Smog Standard. San Francisco
Chronicle, San Francisco, CA, April 15, 2004.
Cole, D. N., J. W. v. Wagtendonk, M. P. McClaran, P. E. Moore, and N. K.
McDougald. 2004. Response of mountain meadows to grazing by recreational
pack stock. Journal of Range Management 57:153-160.
Corn, P. S. 2003. Amphibian breeding and climate change: importance of snow in the
mountains. Conservation Biology 17:622-625.
Corn, P. S. 2005. Climate change and amphibians. Animal Biodiversity and
Conservation 28:59-67.
Corn, P. S., and F. A. Vertucci. 1992. Descriptive risk assessment of the effects of
acidic deposition on rocky-mountain amphibians. Journal of Herpetology
26:361-369.
Cory, L. 1963. Effects of introduced trout on the evolution of native frogs in the high
Sierra Nevada mountains. Page 172 in J. A. Moore (Ed.). Proceedings of the
XVI International Congress of Zoology. XVI International Congress of
Zoology, Washington, D.C.
Crump, M. L., F. R. Hensley, and K. L. Clark. 1992. Apparent decline of the golden
toad: Underground or extinct? Copeia 2:413-420.
Cunningham, A. A., T. E. S. Langton, P. M. Bennett, J. F. Lewin, S. E. N. Drury, R.
E. Gough, and S. K. MacGregor. 1996. Pathological and microbiological
findings from incidents of unusual mortality of the common frog (Rana
62
temporaria). Philosophical Transactions of the Royal Society of London
Series B-Biological Sciences 351:1539-1557.
Daszak, P., L. Berger, A. A. Cunningham, A. D. Hyatt, D. E. Green, and R. Speare.
1999. Emerging infectious diseases and amphibian population declines.
Emerging Infectious Diseases 5:735-748.
Daszak, P., A. A. Cunningham, and A. D. Hyatt. 2001. Anthropogenic environmental
change and the emergence of infectious diseases in wildlife. Acta Tropica
78:103-116.
Daszak, P., A. A. Cunningham, and A. D. Hyatt. 2003. Infectious disease and
amphibian population declines. Diversity and Distributions 9:141-150.
Daszak, P., A. Strieby, A. A. Cunningham, J. E. Longcore, C. Brown, and D. Porter.
2004. Experimental evidence that the bullfrog (Rana catesbeiana) is a
potential carrier of chytridiomycosis, an emerging fungal disease of
amphibians. Herpetological Journal 14:201-207.
Davidson, C. 2004. Declining downwind: Amphibian population declines in
California and historical pesticide use. Ecological Applications 14:1892-1902.
Davidson, C., H. B. Shaffer, and M. R. Jennings. 2001. Declines of the California
red-legged frog: Climate, UV-B, habitat, and pesticides hypotheses.
Ecological Applications 11:464-479.
Davidson, C., H. B. Shaffer, and M. R. Jennings. 2002. Spatial tests of the pesticide
drift, habitat destruction, UV-B, and climate-change hypotheses for California
amphibian declines. Conservation Biology 16:1588-1601.
63
Davidson, E. W., M. Parris, J. P. Collins, J. E. Longcore, A. P. Pessier, and J.
Brunner. 2003. Pathogenicity and transmission of chytridiomycosis in tiger
salamanders (Ambystoma tigrinum). Copeia 2003:601-607.
Davis, F. W., and D. M. Stoms. 1996. Sierran vegetation: A gap analysis. Pages 671-
689 in Sierra Nevada Ecosystem Project: Final Report to Congress. University
of California, Centers for Water and Wildland Resources, Davis, CA.
Dettinger, M. D., and D. R. Cayan. 1995. Large-Scale Atmospheric Forcing of
Recent Trends toward Early Snowmelt Runoff in California. Journal of
Climate 8:606-623.
Diamond, J. A. 1984. Historic extinctions: their mechanisms, and their lessons for
understanding prehistoric extinctions. Pages 824-862 in P. S. Martin, and R.
Klein (Eds.). Quaternary Extinctions. University of Arizona Press, Tucson,
AZ.
Doak, D. F., and M. G. Loso. 2003. Effects of grizzly bear digging on alpine plant
community structure. Arctic Antarctic and Alpine Research 35:421-428.
Drost, C. A., and G. M. Fellers. 1996. Collapse of a regional frog fauna in the
Yosemite area of the California Sierra Nevada, USA. Conservation Biology
10:414-425.
Dupuis, L. A., J. N. M. Smith, and F. Bunnell. 1995. Relation of Terrestrial-Breeding
Amphibian Abundance to Tree-Stand Age. Conservation Biology 9:645-653.
Dusi, J. L. 1949. The natural occurrence of "red-leg", Pseudomonas hydrophila in a
population of American toads, Bufo americanus. Ohio Journal of Science
49:70-72.
64
Emerson, H., and C. Norris. 1905. "Red-leg" -- An infectious disease of frogs. The
Journal of Experimental Medicine 7:32-58.
Erman, N. 1996. Status of aquatic invertebrates. Pages 987-1008 in Sierra Nevada
Ecosystem Project: Final Report to Congress. University of California,
Centers for Water and Wildland Resources, Davis, CA.
Fellers, G. M., D. E. Green, and J. E. Longcore. 2001. Oral chytridiomycosis in the
mountain yellow-legged frog (Rana muscosa). Copeia 2001:945-953.
Fellers, G. M., L. L. McConnell, D. Pratt, and S. Datta. 2004. Pesticides in mountain
yellow-legged frogs (Rana muscosa) from the Sierra Nevada mountains of
California, USA. Environmental Toxicology and Chemistry 23:2170-2177.
Fleischner, T. L. 1994. Ecological costs of livestock grazing in Western North
America. Conservation Biology 8:629-644.
Flenniken, M., R. R. McEldowney, W. C. Leininger, G. W. Frasier, and M. J. Trlica.
2001. Hydrologic responses of a montane riparian ecosystem following cattle
use. Journal of Range Management 54:567-574.
Frankel, O. H., and M. E. Soulé 1981. Conservation and Evolution. Cambridge
University Press, Cambridge, Massachusetts.
Gillespie, G. R. 2001. The role of introduced trout in the decline of the spotted tree
frog (Litoria spenceri) in south-eastern Australia. Biological Conservation
100:187-198.
Gillespie, G. R., and J.-M. Hero. 1999. Potential impacts of introduced fish and fish
translocations on Australian amphibians in A. Campbell (Ed.). Declines and
65
Disappearances of Australian Frogs. Environment Australia, Canberra,
Australia.
Glorioso, J. C., R. L. Amborski, G. F. Amborski, and D. D. Culley. 1974.
Microbiological studies on septicemic bullfrogs (Rana catesbeiana).
American Journal of Veterinary Research 35:1241-1245.
Green, D. E., K. A. Converse, and A. K. Schrader. 2002. Epizootiology of sixty-four
amphibian morbidity and mortality events in the USA, 1996-2001. Annals of
the New York Academy of Sciences 969:323-339.
Green, D. E., and C. Kagarise Sherman. 2001. Diagnostic histological findings in
Yosemite toads (Bufo canorus) from a die-off in the 1970s. Journal of
Herpetology 35:92-103.
Griffin, D. E. 1997. Virus-induced immune suppression. Pages 207-233 in N.
Nathanson (Ed.). Viral Pathogenesis. Lippincott-Raven Publishers,
Philadelphia, Pennsylvania.
Grinnell, J., and C. L. Camp. 1917. A distributional list of the amphibians and reptiles
of California. University of California Publications in Zoology 17:127-208.
Grinnell, J., and T. I. Storer 1924. Animal Life in the Yosemite. University of
California Press, Berkeley, California.
Hall, R. J., and P. F. P. Henry. 1992. Assessing effects of pesticides on amphibians
and reptiles - status and needs. Herpetological Journal 2:65-71.
Hanselmann, R., A. Rodriguez, M. Lampo, L. Fajardo-Ramos, A. A. Aguirre, A. M.
Kilpatrick, J. P. Rodriguez, and P. Daszak. 2004. Presence of an emerging
66
pathogen of amphibians in introduced bullfrogs Rana catesbeiana in
Venezuela. Biological Conservation. 120:115-119.
Hanski, I. 1982. Dynamics of regional distribution - the core and satellite species
hypothesis. Oikos 38:210-221.
Hanski, I. 1983. Coexistence of competitors in patchy environment. Ecology 64:493-
500.
Hanski, I. 1989. Metapopulation dynamics - Does it help to have more of the same.
Trends in Ecology & Evolution 4:113-114.
Hanski, I., and M. Gilpin. 1991. Metapopulation dynamics - Brief-history and
conceptual domain. Biological Journal of the Linnean Society 42:3-16.
Hanski, I., A. Moilanen, and M. Gyllenberg. 1996. Minimum viable metapopulation
size. American Naturalist 147:527-541.
Hanski, I., and O. Ovaskainen. 2002. Extinction debt at extinction threshold.
Conservation Biology 16:666-673.
Harrison, S. 1991. Local extinction in a metapopulation context: an empirical
evaluation. Biological Journal of the Linnean Society 42:73-88.
Hatch, A. C., and A. R. Blaustein. 2003. Combined effects of UV-B radiation and
nitrate fertilizer on larval amphibians. Ecological Applications 13:1083-1093.
Hayes, M. P., and M. R. Jennings. 1986. Decline of ranid frog species in Western
North America: Are bullfrogs (Rana catesbeiana) responsible? Journal of
Herpetology 20:490-509.
Hayes, T. B., A. Collins, M. Lee, M. Mendoza, N. Noriega, A. A. Stuart, and A.
Vonk. 2002. Hermaphroditic, demasculinized frogs after exposure to the
67
herbicide atrazine at low ecologically relevant doses. Proceedings of the
National Academy of Sciences 99:5476-5480.
Hays, J. B., A. R. Blaustein, J. M. Kiesecker, P. D. Hoffman, I. Pandelova, D. Coyle,
and T. Richardson. 1996. Developmental responses of amphibians to solar and
artificial UVB sources: A comparative study. Photochemistry and
Photobiology 64:449-456.
Hecnar, S. J. 1995. Acute and chronic toxicity of ammonium nitrate fertilizer to
amphibians from southern Ontario. Environmental Toxicology and Chemistry
14:2131-2137.
Hero, J.-M., and G. R. Gillespie. 1997. Epidemic disease and amphibian declines in
Australia. Conservation Biology 11:1023-1025.
Heyer, W. R. 2003. Ultraviolet-B and amphibia. Bioscience 53:540-541.
Hird, D. W., S. L. Diesch, R. G. McKinnell, E. Gorham, F. B. Martin, S. W. Kurtz,
and C. Dubrovolny. 1981. Aeromonas hydrophila in wild caught frogs and
tadpoles (Rana pipiens) in Minnesota. Laboratory Animal Science 31:166-
169.
Houlahan, J. E., C. S. Findlay, B. R. Schmidt, A. H. Meyer, and S. L. Kuzmin. 2000.
Quantitative evidence for global amphibian population declines. Nature
404:752-755.
Hubbs, C. L., and O. L. Wallis. 1949. The native fish fauna of Yosemite National
Park and its preservation. Yosemite Nature Notes 27:131-144.
Hunsaker, D., and F. E. Potter, Jr. 1960. Red-leg in a natural population of
amphibians. Herpetologica 16:285-286.
68
Ingles, L. G. 1965. Mammals of the Pacific States. Stanford University Press,
Stanford, CA.
Jackson, L. A. 2004. The Mule Men. Mountain Press Publishing Company, Missoula,
Montana.
Jansen, A., and M. Healey. 2003. Frog communities and wetland condition:
relationships with grazing by domestic livestock along an Australian
floodplain river. Biological Conservation 109:207-219.
Jennings, M. R. 1996. Status of Amphibians. Pages 921-944 in Sierra Nevada
Ecosystem Project: Final Report to Congress. University of California,
Centers for Water and Wildland Resources, Davis, CA.
Jennings, M. R., and M. P. Hayes. 1994. Amphibian and Reptile Species of Special
Concern in California. Pages iv-255. California Department of Fish & Game,
Inland Fisheries Division, Rancho Cordova, CA.
Jepson, W. L. 1975. A Manual of the Flowering Plants of California. University of
California Press, Berkeley, CA.
Johnson, J. G. 1974. Extinction of "perched" faunas. Geology 2:479-482.
Johnston, B., and L. Frid. 2002. Clear cut logging restricts the movements of
terrestrial Pacific giant salamanders (Dicamptodon tenebrosus Good).
Canadian Journal of Zoology 80:2170-2177.
Kagarise Sherman, C. 1980. A Comparison of the Natural History and Mating System
of two Anurans: Yosemite Toads (Bufo canorus) and Black Toads (Bufo
exsul). University of Michigan, Ann Arbor. University Microfilm
International 8106225.
69
Kagarise Sherman, C., and M. L. Morton. 1984. The toad that stays on its toes.
Natural History 93:72-78.
Kagarise Sherman, C., and M. L. Morton. 1993. Population declines of Yosemite
toads in the eastern Sierra Nevada of California. Journal of Herpetology
27:186-198.
Karlstrom, E. L. 1962. The toad genus Bufo in the Sierra Nevada of California.
University of California Publications in Zoology 62:1-104.
Kati, V., P. Devillers, M. Dufrene, A. Legakis, D. Vokou, and P. Lebrun. 2004.
Testing the value of six taxonomic groups as biodiversity indicators at a local
scale. Conservation Biology 18:667-675.
Kats, L. B., J. M. Kiesecker, D. P. Chivers, and A. R. Blaustein. 2000. Effects of UV-
B radiation on anti-predator behavior in three species of amphibians. Ethology
106:921-931.
Kattelmann, R., and M. Embury. 1996. Riparian areas and wetlands. Pages 201-269
in Sierra Nevada Ecosystem Project: Final Report to Congress. U.C., Davis,
Centers for Water and Wildlife Resources, Davis, CA.
Kie, J. G., and B. B. Boroski. 1996. Cattle distribution, habitats, and diets in the
Sierra Nevada of California. Journal of Range Management 49:482-488.
Kiesecker, J. M., and A. R. Blaustein. 1995. Synergism between UV-B radiation and
a pathogen magnifies amphibian embryo mortality in nature. Proceedings of
the National Academy of Sciences 92:11049-11052.
Kiesecker, J. M., A. R. Blaustein, and L. K. Belden. 2001. Complex causes of
amphibian population declines. Nature 410:681-684.
70
Kinney, W. C. 1996. Conditions of rangelands before 1905. Pages 31-45 in Sierra
Nevada Ecosystem Project: Final Report to Congress. U.C. Davis, Centers for
Water and Wildlands Resources, Davis, CA.
Knapp, R. A. 2002. Non-native fish introductions and the reversibility of amphibian
declines in the Sierra Nevada. Pages 127-132 in D. D. Murphy, and P. A.
Stine (Eds.). Sierra Nevada Science Symposium. USDA Forest Service
General Technical Report, Kings Beach, California.
Knapp, R. A. 2005. Effects of nonnative fish and habitat characteristics on lentic
herpetofauna in Yosemite National Park, USA. Biological Conservation
121:265-279.
Knapp, R. A., P. S. Corn, and D. E. Schindler. 2001a. The Introduction of Nonnative
Fish into Wilderness Lakes: Good Intentions, Conflicting Mandates, and
Unintended Consequences. Ecosystems 4:275-278.
Knapp, R. A., and K. R. Matthews. 1996. Livestock grazing, golden trout, and
streams in the Golden Trout Wilderness, California: impacts and management
implications. North American Journal of Fisheries Management 16:805-820.
Knapp, R. A., and K. R. Matthews. 1998. Eradication of non-native fish from a small
mountain lake: gill netting as a non-toxic alternative to the use of rotenone.
Restoration Ecology 6:207-213.
Knapp, R. A., and K. R. Matthews. 2000. Non-native fish introductions and the
decline of the mountain yellow-legged frog from within protected areas.
Conservation Biology 14:428-438.
71
Knapp, R. A., K. R. Matthews, and O. Sarnelle. 2001b. Resistance and resilience of
alpine lake fauna to fish introductions. Ecological Monographs 71:401-421.
Knapp, R. A., and J. A. T. Morgan. 2006. Tadpole mouthpart depigmentation as an
accurate indicator of chytridiomycosis, an emerging disease of amphibians.
Copeia 2006:188–197.
Knight, J. 2001. If they could talk to the animals... Nature 414:246-247.
Lande, R., and S. H. Orzack. 1988. Extinction dynamics of age-structured
populations in a fluctuating environment. Proceedings of the National
Academy of Sciences 85:7418-7421.
Landres, P. B., J. Verner, and J. W. Thomas. 1988. Ecological uses of vertebrate
indicator species: a critique. Conservation Biology 2:316-328.
Lane, E. P., C. Weldon, and J. Bingham. 2003. Histological evidence of
chytridiomycete fungal infection in a free-ranging amphibian, Afrana
fuscigula (Anura : Ranidae), in South Africa. Journal of the South African
Veterinary Association 74:20-21.
Laurance, W. F., K. R. McDonald, and R. Speare. 1996. Epidemic disease and the
catastrophic decline of Australian rain forest frogs. Conservation Biology
10:406-413.
Lawler, J. J., D. White, J. C. Sifneos, and L. L. Master. 2003. Rare species and the
use of indicator groups for conservation planning. Conservation Biology
17:875-882.
Licht, L. E. 1996. Amphibian decline still a puzzle. Bioscience 46:172-173.
72
Licht, L. E. 2003. Shedding light on ultraviolet radiation and amphibian embryos.
Bioscience 53:551-561.
Licht, L. E., and K. P. Grant. 1997. The effects of ultraviolet radiation on the biology
of amphibians. American Zoologist 37:137-145.
Linder, G., R. Hazelwood, D. Palawski, M. Bollman, D. Wilborn, J. Malloy, K.
Dubois, S. Ott, G. Pascoe, and J. Dalsoglio. 1994. Ecological Assessment for
the Wetlands at Milltown Reservoir, Missoula, Montana - Characterization of
Emergent and Upland Habitats. Environmental Toxicology and Chemistry
13:1957-1970.
Lips, K. R. 1998. Decline of a tropical montane amphibian fauna. Conservation
Biology 12:106-117.
Lips, K. R. 1999. Mass mortality and population declines of anurans at an upland site
in western Panama. Conservation Biology 13:117-125.
Lips, K. R., D. E. Green, and R. Papendick. 2003. Chytridiomycosis in wild frogs
from southern Costa Rica. Journal of Herpetology 37:215-218.
Lips, K. R., J. R. Mendelson, III, A. Munoz-Alonso, L. Canseco-Marquez, and D. G.
Mulcahy. 2004. Amphibian population declines in montane southern Mexico:
resurveys of historical localities. Biological Conservation 119:555-564.
Little, E. E., R. D. Calfee, D. L. Fabacher, C. Carey, V. S. Blazer, and E. M.
Middleton. 2003. Effects of ultraviolet radiation on toad early life stages.
Environmental Science and Pollution Research 10:167-172.
73
Longcore, J. E., A. P. Pessier, and D. K. Nichols. 1999. Batrachochytrium
dendrobatidis gen. et sp. nov., a chytrid pathogenic to amphibians. Mycologia
91:219-227.
MacArthur, R. H., and E. O. Wilson 1967. The Theory of Island Biogeography.
Princeton University Press, Princeton, New Jersey.
Magilligan, F. J., and P. F. McDowell. 1997. Stream channel adjustments following
elimination of cattle grazing. Journal of the American Water Resources
Association 33:867-878.
Marsh, D. M. 2001. Fluctuations in amphibian populations: a meta-analysis.
Biological Conservation 101:327-335.
Martin, D. L. 1990 [abstract]. Population status of the Yosemite toad (Bufo canorus):
An interim report. Page 74 in Joint Annual Meeting of the Herpetologists'
League and the Society for the Study of Amphibians and Reptiles, Tulane
University, New Orleans, Louisiana.
Martin, D. L. 1991a [abstract]. Population census of a species of special concern: The
Yosemite toad (Bufo canorus). Page 31 in Fourth Biennial Conference of
Research in California's National Parks. Cooperative National Parks
Resources Studies Unit, University of California, Davis, California.
Martin, D. L. 1991b [abstract]. The dramatic decline of a species of special concern:
The Yosemite Toad (Bufo canorus). Page 78 in Joint Annual Meeting of the
Herpetologists' League and the Society for the Study of Amphibians and
Reptiles, Penn State University, University Park, Pennsylvania.
74
Martin, D. L. 1993 [abstract]. Standardization of Survey Techniques for Anurans in
the Sierra Nevada of California. Page 52 in 1993 Conference, Western Section
of the Wildlife Society, Biological Conservation, Monterey Hyatt, Monterey,
CA.
Martin, D. L. 1994 [abstract]. Standardized survey of anurans in the Sierra Nevada.
Page 166 in M. Davies, and R. M. Norris (eds.). Second World Congress of
Herpetology, University of Adelaide, South Australia.
Martin, D. L., W. E. Bros, D. L. Dondero, M. R. Jennings, and H. H. Welsh. 1993.
Sierra Nevada Anuran Survey: An Investigation of Amphibian population
abundance in The National Forests of The Sierra Nevada of California.
Canorus Ltd., Sacramento, CA.
Martinez-Solano, I., J. Bosch, and M. Garcia-Paris. 2003. Demographic trends and
community stability in a montane amphibian assemblage. Conservation
Biology 17:238-244.
Matthews, K. R., and R. A. Knapp. 1999. A study of high mountain lake fish stocking
effects in Sierra Nevada Wilderness. International Journal of Wilderness 5:24-
26.
Matthews, K. R., R. A. Knapp, and K. L. Pope. 2002. Garter snake distributions in
high-elevation aquatic ecosystems: Is there a link with declining amphibian
populations and nonnative trout introductions? Journal of Herpetology 36:16-
22.
Matthews, K. R., and K. L. Pope. 1999. A telemetric study of the movement patterns
and habitat use of Rana muscosa, the mountain yellow-legged frog, in a high-
75
elevation basin in Kings Canyon National Park, California. Journal of
Herpetology 33:615-624.
Maurer, J., and S. Thompson. 2008. Experimental Aquatic Restoration in Yosemite
National Park to Inform Aquatic Management and Recover the Sierra Nevada
Yellow-legged Frog. Pages 17-19 in California-Nevada Amphibian
Populations Task Force, San Diego, CA.
May, R. M. 1973. Complexity and Stability in Model Ecosystems. Princeton
University Press, Princeton, New Jersey.
McCallum, H. I., and A. P. Dobson. 1995. Detecting disease and parasite threats to
endangered species and ecosystems. Trends in Ecology & Evolution 10:190-
194.
McCoy, E. D. 1994. Amphibian decline - a scientific dilemma in more ways than one.
Herpetologica 50:98-103.
McIntosh, R. P. 1985. The Background of Ecology: Concept and Theory. Cambridge
University Press, Cambridge, UK.
Menke, J. W., C. Davis, and P. Beesley. 1996. Rangeland Assessment. Pages 901-972
in Sierra Nevada Ecosystem Project: Final Report to Congress. University of
California, Centers for Water and Wildland Resources, Davis, CA.
Middleton, E. M., J. R. Herman, E. A. Celarier, J. W. Wilkinson, C. Carey, and R. J.
Rusin. 2001. Evaluating ultraviolet radiation exposure with satellite data at
sites of amphibian declines in Central and South America. Conservation
Biology 15:914-929.
76
Morehouse, E. A., T. Y. James, A. R. D. Ganley, R. Vigalys, L. Berger, P. J. Murphy,
and J. E. Longcore. 2003. Multilocus sequence typing suggests the chytrid
pathogen of amphibians is a recently emerged clone. Molecular Ecology
12:395-403.
Morrison, C., and J. M. Hero. 2003. Geographic variation in life-history
characteristics of amphibians: a review. Journal of Animal Ecology 72:270-
279.
Morton, M. L. 1981. Seasonal changes in total body lipid and liver weight in the
Yosemite toad. Copeia 1981:234-238.
Morton, M. L. 1982. Natural history of the Yosemite toad. National Geographic
Society Research Reports 14:499-503.
Moyle, P. B. 1976. Fish introductions in California: History and impact on native
fishes. Biological Conservation 9:101-118.
Muir, J. 1877. On the post-glacial history of Sequoia gigantea. Proceedings of the
American Association for the Advancement of Science 25.
Mullally, D. P., Pvt. 1953. Observations on the ecology of the toad Bufo canorus.
Copeia 1953:182-183.
Mullally, D. P., Pvt., and J. D. Cunningham. 1956. Aspects of the thermal ecology of
the Yosemite toad. Herpetologica 12:57-67.
Muths, E., P. S. Corn, A. P. Pessier, and D. E. Green. 2003. Evidence for disease-
related amphibian decline in Colorado. Biological Conservation 110:357-365.
Noriega, N. C., and T. B. Hayes. 2000. DDT congener effects on secondary sex
coloration in the reed frog Hyperolius argus: a partial evaluation of the
77
Hyperolius argus endocrine screen. Comparative Biochemistry and
Physiology B-Biochemistry & Molecular Biology 126:231-237.
Norris, K. 2004. Managing threatened species: the ecological toolbox, evolutionary
theory and declining-population paradigm. Journal of Applied Ecology
41:413–426.
Noss, R. F. 1990. Indicators for monitoring biodiversity: a hierarchal approach.
Conservation Biology 4:413-426.
Oliver, J. A. 1955. The Natural History of North American Amphibians and Reptiles.
D. van Nostrand Co., Inc., Princeton, New Jersey.
Ouellet, M., I. Mikaelian, B. D. Pauli, J. Rodrigues, and D. M. Green. 2005.
Historical evidence of widespread chytrid infection in North American
amphibian populations. Conservation Biology 19:1431-1440.
Palen, W. J., D. E. Schindler, M. J. Adams, C. A. Pearl, R. B. Bury, and S. A.
Diamonds. 2002. Optical characteristics of natural waters protect amphibians
from UV-B in the US Pacific Northwest. Ecology 83:2951-2957.
Pechmann, J. H. K., D. E. Scott, R. D. Semlitsch, J. P. Caldwell, L. J. Vitt, and J. W.
Gibbons. 1991. Declining amphibian populations - the problem of separating
human impacts from natural fluctuations. Science 253:892-895.
Pechmann, J. H. K., and H. M. Wilbur. 1994. Putting declining amphibian
populations in perspective - Natural fluctuations and human impacts.
Herpetologica 50:65-84.
Peters, R. H. 1991. A Critique for Ecology. Cambridge University Press, Cambridge,
UK.
78
Pilliod, D. S., R. B. Bury, E. J. Hyde, C. A. Pearl, and P. S. Corn. 2003. Fire and
amphibians in North America. Forest Ecology and Management 178:163-181.
Pimm, S. L. 1991. The Balance of Nature: Ecological Issues in the Conservation of
Species and Communities. University of Chicago Press, Chicago, IL.
Pister, E. P. 2001. Wilderness Fish Stocking: History and Perspective. Ecosystems
4:279-286.
Platts, W. S. 1991. Livestock grazing in W. R. Meehan (Ed.). Influences of Forest
and Rangeland Management on Salmonid Fishes and their Habitats. American
Fisheries Society, Bethesda, MD.
Pope, K. L., and K. R. Matthews. 2001. Movement ecology and seasonal distribution
of mountain yellow-legged frogs, Rana muscosa, in a high-elevation Sierra
Nevada basin. Copeia 101:787-793.
Pounds, J. A. 2001. Climate and amphibian declines. Nature 410:639-640.
Pounds, J. A., M. R. Bustamante, L. A. Coloma, J. A. Consuegra, M. P. L. Fogden, P.
N. Foster, E. L. Marca, K. L. Masters, A. Merino-Viteri, R. Puschendorf, S. R.
Ron, G. A. Sánchez-Azofeifa, C. J. Still, and B. E. Young. 2006. Widespread
amphibian extinctions from epidemic disease driven by global warming.
Nature 439:161-167.
Pounds, J. A., and M. L. Crump. 1994. Amphibian declines and climate disturbance:
The case of the golden toad and the harlequin frog. Conservation Biology
8:72-85.
Pupacko, A. 1993. Variations in northern Sierra-Nevada streamflow - Implications of
climate-change. Water Resources Bulletin 29:283-290.
79
Rachowicz, L. J. 2002. Mouthpart Pigmentation in Rana muscosa tadpoles: seasonal
changes without chytridiomycosis. Herpetological Review 33:263-265.
Rachowicz, L. J., J. M. Hero, A. J.M., J. W. Taylor, J. A. T. Morgan, V. T.
Vredenburg, J. P. Collins, and C. J. Briggs. 2005. The novel and endemic
pathogen hypotheses: competing explanations for the origin of emerging
diseases of wildlife. Conservation Biology 19:1441-1448.
Rachowicz, L. J., R. A. Knapp, J. A. T. Morgan, M. J. Stice, V. T. Vredenburg, J. M.
Parker, and C. J. Briggs. 2006. Emerging infectious disease as a proximate
cause of amphibian mass mortality. Ecology 87:1671–1683.
Rachowicz, L. J., and V. T. Vredenburg. 2004. Transmission of Batrachochytrium
dendrobatidis within and between amphibian life stages. Diseases of Aquatic
Organisms 61:75-83.
Ratliff, R. D. 1982. A Meadow Site Classification for the Sierra Nevada, California.
GTR-PSW-60. Pacific Southwest Research Station, Forest Service, U.S. Dept.
of Agriculture, Berkeley, CA.
Ratliff, R. D. 1985. Meadows in the Sierra Nevada of California: State of knowledge.
GTR-PSW-84. Pacific Southwest Forest and Range Experiment Station,
Forest Service, U.S. Dept. of Agriculture, Berkeley, CA.
Reichenbach-Klinke, H., and E. Elkan 1965. The Principal Diseases of Lower
Vertebrates. Academic Press Inc., New York, NY.
Retallick, R. W. R., H. McCallum, and R. Speare. 2004. Endemic infection of the
amphibian chytrid fungus in a frog community post-decline. PLoS Biology
2:1965-1971.
80
Ripple, W. J., and R. L. Beschta. 2003. Wolf reintroduction, predation risk, and
cottonwood recovery in Yellowstone National Park. Forest Ecology and
Management 184:299-313.
Ron, S. R., W. E. Duellman, L. A. Coloma, and M. R. Bustamante. 2003. Population
Decline of the Jambato Toad Atelopus ignescens (Anura: Bufonidae) in the
Andes of Ecuador. Journal of Herpetology 37:116-126.
Root, T. L., J. T. Price, K. R. Hall, S. H. Schneider, C. Rosenzweig, and J. A. Pounds.
2003. Fingerprints of global warming on wild animals and plants. Nature
421:57-60.
Roughgarden, J. 1975. Populations dynamics in a stochastic environment: Spectral
theory for the linearized N-species Lotka-Volterra competition equations.
Theoretical Population Biology 7:1-12.
Sanders, R. 2003. Museum scientists to repeat landmark 80-year-old Yosemite
wildlife survey. UC Berkeley News.
Sarkar, S. 1996. Ecological theory and anuran declines. Bioscience 46:199-207.
Schmidt, R. H. 1987. Historical records of gray wolves in California. Wolf 5:31-35.
Schmidt, R. H. 1991. Gray wolves in California: their presence and absence.
California Fish and Game 77:79-85.
Schwarzkopf, L., and R. A. Alford. 1996. Desiccation and shelter-site use in a
tropical amphibian: comparing toads with physical models. Functional
Ecology 10:193-200.
Scott, N. J. 1993. Postmetamorphic death syndrome. Froglog 7:1-2.
81
Semlitsch, R. D. 2000. Principles for management of aquatic-breeding amphibians.
Journal of Wildlife Management 64:615-631.
Semlitsch, R. D. 2002. Critical elements for biologically based recovery plans of
aquatic-breeding amphibians. Conservation Biology 16:619-629.
Semlitsch, R. D. (Ed.). 2003a. Amphibian Conservation. Smithsonian Books,
Washington, D.C.
Semlitsch, R. D. 2003b. Conservation of pond-breeding amphibians. Pages 8-23 in R.
D. Semlitsch (Ed.). Amphibian Conservation. Smithsonian Books,
Washington, D. C.
Semlitsch, R. D., and B. B. Rothermel. 2003. A foundation for conservation and
management of amphibians. Pages 242-259 in R. D. Semlitsch (Ed.).
Amphibian Conservation. Smithsonian Books, Washington, D.C.
Shaffer, M. L. 1981. Minimum population sizes for species conservation. Bioscience
31:131-134.
Shebley, W. H. 1917. History of the introduction of food and game fishes into the
waters of California. California Fish and Game 3:3-12.
Shotts, E. B., Jr. 1984. Aeromonas. Pages 49-57 in G. L. Hoff, F. L. Frye, and E. R.
Jacobson (Eds.). Disease of Amphibians and Reptiles. Plenum Press, New
York, N.Y.
Shrader-Frechette, K. R., and E. D. McCoy (Eds.). 1993. Method in Ecology:
Strategies for Conservation. Cambridge University Press, New York, N.Y.
Simberloff, D. 1994. Habitat fragmentation and population extinction of birds. Ibis
137:S105-S111.
82
Simberloff, D. 1998. Flagships, umbrellas, and keystones: Is single-species
management passé in the landscape era? Biological Conservation 83:247-257.
Simberloff, D., and L. G. Abele. 1975. Island biogeography theory and conservation
practice. Science 191:285-286.
Sjogren, P. 1991. Extinction and isolation gradients in metapopulations: The case of
the pool frog (Rana lessonae). Biological Journal of the Linnean Society
42:135-147.
Snyder, J. O. 1933. California trout. California Fish and Game 19:81-112.
Soulé, M. E. 1985. What is conservation biology? Bioscience 35:727-734.
Soulé, M. E. 1986. Conservation Biology: Science of Scarcity and Diversity. Sinauer,
Sunderland, MA.
Soulé, M. E. 1987. Viable Populations for Conservation. Cambridge University Press,
Cambridge.
Soulé, M. E., and B. A. Wilcox (Eds.). 1980. Conservation Biology: An
Evolutionary--Ecological Perspective. Sinauer Associates, Sunderland, MA.
Sparling, D. W., G. M. Fellers, and L. L. McConnell. 2001. Pesticides and amphibian
population declines in California, USA. Environmental Toxicology and
Chemistry 20:1591-1595.
Stebbins, R. C. 1951. Amphibians of Western North America. University of
California Press, Berkeley, California.
Stebbins, R. C. 1966. A Field Guide to Western Reptiles and Amphibians. Houghton
Mufflin Company, Boston, Mass.
83
Stebbins, R. C. 1985. A Field Guide to Western Reptiles and Amphibians. Houghton
Mifflin Co., Boston, Mass.
Stebbins, R. C., and N. W. Cohen 1995. A Natural History of Amphibians. Princeton
University Press, Princeton, NJ.
Storer, T. I. 1925. A synopsis of the amphibia of California. University of California
Publications in Zoology 27:1-307.
Storer, T. I., and L. P. Tevis, Jr. 1955. California Grizzly. University of California
Press, Berkeley, CA.
Storer, T. I., and R. L. Usinger 1963. Sierra Nevada Natural History: An Illustrated
Handbook. University of California Press, Berkeley, CA.
Stuart, S. N., J. S. Chanson, N. A. Cox, B. E. Young, A. S. L. Rodrigues, D. L.
Fischman, and R. W. Waller. 2004. Status and trends of amphibian declines
and extinctions worldwide. Science 306:1783-1786.
Sudworth, G. B., and H. Gannett. 1900. Stanislaus and Lake Tahoe Forest Reserves,
California, and adjacent territory. Twenty-first annual report of the USGS,
part V, Forest reserves, Washington, D.C.
Sumner, L., and R. M. Leonard. 1947. Protecting mountain meadows. Sierra Club
Bulletin 32:53-66.
Tardiff, S. E., and J. A. Stanford. 1998. Grizzly Bear Digging: Effects on Subalpine
Meadow Plants in Relation to Mineral Nitrogen Availability. Ecology
79:2219-2228.
Taylor, S. K., E. S. Williams, and K. W. Mills. 1999. Effects of malathion on disease
susceptibility in Woodhouse's toads. Journal of Wildlife Diseases 35:536-541.
84
Thilenius, J. F. 1975. Alpine Range Management In the Western United States --
Principles, Practices, and Problems: The Status of Our Knowledge. RM-157.
Pages iv-32. Rocky Mountain Forest and Range Experiment Station, USDA
Forest Service, Fort Collins, Colorado.
Travis, J. 1994. Calibrating our expectations in studying amphibian populations.
Herpetologica 50:104-108.
Trimble, S. W., and A. C. Mendel. 1995. The cow as a geomorphic agent: a critical-
review. Geomorphology 13:233-253.
USDA, F. S. 2003. Sierra Nevada Forest Plan Amendment (SNFPA): Management
Review and Recommendations -- Part 1: Assessing the Need For Change;
Impacts to Grazing; Impacts from Standards and Guidelines for Sensitive
Species. R5-MB-012. Pages 61-75, Pacific Southwest Region.
Vertucci, F. A., and P. S. Corn. 1996. Evaluation of episodic acidification and
amphibian declines in the Rocky Mountains. Ecological Applications 6:449-
457.
Vesely, D. G., and W. C. McComb. 2002. Salamander abundance and amphibian
species richness in riparian buffer strips in the Oregon Coast Range. Forest
Science 48:291-297.
Vitt, L. J., J. P. Caldwell, H. Wilbur, M., and D. C. Smith. 1990. Amphibians as
hairbingers of decay. Bioscience 40:418.
Vredenburg, V. T. 2004. Reversing introduced species effects: Experimental removal
of introduced fish leads to rapid recovery of a declining frog. Proceedings of
the National Academy of Sciences 101:7646-7650.
85
Vredenburg, V. T., and A. P. Summers. 2001. Field identification of
Chytridiomycosis in Rana muscosa (Camp 1915). Herpetological Review
32:151-152.
Wake, D. B. 1990. Excerpts from the froglog. Froglog 1:1-14.
Wake, D. B. 1991. Declining amphibian populations. Science 253:860.
Wake, D. B., and H. J. Morowitz. 1990. Declining amphibian populations: A global
phenomenon? Pages 1-11. Report of workshop findings. National Research
Council Board on Biology, Irvine, CA.
Walker, M. V. 1946. Reptiles and amphibians of Yosemite National Park. Yosemite
Nature Notes 15:1-48.
Weldon, C. 2002. Chytridiomycosis survey in South Africa. Froglog 51:1-2.
Weldon, C., L. H. du Preez, A. D. Hyatt, R. Muller, and R. Speare. 2004. Origin of
the Amphibian Chytrid Fungus. Emerging Infectious Diseases. 10:2100-
2105.
Wilcox, B. A. 1980. Insular ecology and conservation. Pages 95-117 in M. E. Soulé,
and B. A. Wilcox, editors. Conservation Biology: An Evolutionary--
Ecological Perspective. Sinauer Associates, Inc., Sunderland, MA.
Williams, J. D., and R. M. Nowak. 1993. Vanishing species in our own backyard:
extinct fish and wildlife of the United States and Canada. Pages 107-139 in L.
Kaufman, and K. Mallory (Eds.). The Last Extinction. MIT Press, Cambridge,
Mass.
Williams, S. 2002. 50 CFR Part 17: 12-month finding for a petition to list the
Yosemite toad. Federal Register 67:75834-75843.
86
Wold, J. L. 1995. Decision Notice and Finding of No Significant Impact for the
Highland Lakes Term Permit and Allotment Management Plan. SO-0592-4.
Pages 1-8. Stanislaus National Forest, Sonora, CA.
Worthylake, K. M., and P. Hovingh. 1989. Mass mortality of salamanders
(Ambystoma tigrinum) by bacteria (Acientobacter) in an oligotrophic seepage
mountain lake. Great Basin Naturalist 49:364-372.
Wright, A. A., and A. H. Wright 1933. Handbook of Frogs and Toads of the United
States and Canada. The Comstock Publishing Co., Inc., Ithaca, New York.
Wright, A. H., and A. A. Wright 1949. Handbook of Frogs and Toads of the United
States and Canada. Comstock Publishing Co., Inc., Ithaca, New York.
Wyman, R. L. 1990. What's happening to the amphibians? Conservation Biology
4:350-352.
Young, B. E., K. R. Lips, J. K. Reaser, R. Ibanez, A. W. Salas, J. R. Cedeno, L. A.
Coloma, S. Ron, E. La Marca, J. R. Meyer, A. Munoz, F. Bolanos, G. Chaves,
and D. Romo. 2001. Population declines and priorities for amphibian
conservation in Latin America. Conservation Biology 15:1213-1223.
Zardus, M., T. Blank, and D. Schulz. 1977. Status of fishes in 137 lakes in Sequoia
and Kings Canyon National Parks, California. U.S. Department of the Interior,
National Parks Service, Sequoia and Lings Canyon National Parks, Three
Rivers, California.
Zhang, T. 1999. Study on fish and amphibian embryo-larval toxicity test.
Environmental Monitoring and Assessment 55:363-369.
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FIGURES
2007
2004
2001
1998
1995
1992
1989
1986
1983
1980
1977
1974
1971
1968
1965
1962
1959
1956
1953
1950
Tioga Pass March-April Snow Depth 1947
1944
1941
1938
1935
1932 1929
Combined snow depths for March-April at Tioga Pass, Mono Co., CA. Dashed line represents the 82 year average 1926 0
50
400 350 300 250 200 150 100 Snow Depth, cm Depth, Snow Figure 1. depth of 159 cm for this period. Data Source: State California, Department Water Resources, Snow Course Survey data. Combine
88
2007
2005
2003
2001
1999
1997
1995
1993 1991
data.
1989 y
1987 1985
Highland Lakes Snow Depth Total
1983
1981
1979 1977
Highland Meadow accumulated snow depth calculated from Jan-May monthly totals. Dashed line 1975 artment of Water Resources, Snow Course Surve p 0
600 500 400 300 200 100 Figure 2. represents the 34 year average depth of 245 cm for this calculated snow depth. Data Source: State California, De Snow Depth, cm Depth, Snow
89
CHAPTER II
POST-BREEDING MOVEMENTS AND CONSERVATION OF ADULT
YOSEMITE TOADS (Bufo canorus)
90
INTRODUCTION
The apparent global decline of amphibian species (Blaustein & Wake 1990;
Wake & Morowitz 1990; Houlahan et al. 2000; Houlahan et al. 2001; Stuart et al.
2004) has focused the attention of conservation biologists on the need for biologically based recovery plans for amphibians (Semlitsch 2000, 2002), but the development of a comprehensive recovery plan for a particular amphibian species requires an intimate understanding of their use of different habitat patches for breeding, foraging and for overwintering, which may be temporally and spatially separated within the environment (Wilbur 1980; Sinsch 1990). Most studies of amphibian ecology, particularly those of pool-breeding anurans, have thus far focused primarily on breeding sites because adult anurans are easily detected in pools during the short breeding season. Further, embryonic and larval forms are easily detected throughout much of the active season in the breeding pools, thereby indicating the presence of a reproducing population and providing at least some indication of relative abundance
(e.g., Martin et al. 1992; Brown 2002; Lind et al. 2006). Once breeding is concluded, however, adult anurans typically immigrate to terrestrial foraging habitats that may be some distance away from the breeding pools; but because many pool-breeding amphibians are typically fossorial, or drawn to habitat with dense vegetation, they are usually very difficult to locate in the terrestrial habitats they occupy. This secretive behavior and the attendant challenges to conducting research on relatively small amphibians in their terrestrial habitats often results in the terrestrial ecology, which constitutes the majority of amphibian life history, being overlooked by land managers
91
even though terrestrial habitats are an essential component in the protection and recovery of amphibian populations (Dodd & Cade 1998; Semlitsch 1998, 2000, 2002;
Semlitsch 2003b; Semlitsch & Bodie 2003). Therefore, neither biologically based recovery plans nor designation of critical habitat for endangered amphibians under the US Endangered Species Act of 1973 can be completed without a good understanding of the seasonal distribution of a species within its environment.
The Yosemite toad (Bufo canorus) is one of several Sierra Nevada anuran species that have suffered marked declines over the last two decades (Martin 1990b;
Bradford 1991; Martin 1991b; Bradford & Gordon 1992; Bradford et al. 1993;
Kagarise Sherman & Morton 1993; Martin et al. 1993; Bradford et al. 1994; Jennings
& Hayes 1994; Martin 1994; Stebbins & Cohen 1995; Drost & Fellers 1996; Jennings
1996), resulting in its being listed as a “Species of Special Concern” by the California
Department of Fish & Game, “Sensitive” on the Region 5 Forester’s Sensitive
Species List (USDA Forest Service 1998) and “warranted” for listing under the
Endangered Species Act, “but precluded by higher priority listing actions” (50 CFR
17 75834).
Ecological studies of B. canorus, like many amphibians, have thus far focused on the breeding biology of this species and to a lesser extent on their movements within the breeding pools and the meadows immediately surrounding them (Mullally
1953; Mullally & Cunningham 1956; Karlstrom 1962; Cunningham 1963; Kagarise
Sherman 1980; Kagarise Sherman & Morton 1993). A few of these studies include anecdotal observations of post reproductive toad movements that suggest individual
B. canorus have fairly restricted home ranges (Mullally & Cunningham 1956;
92
Mullally 1953) and are rarely found more than 90 m from permanent water
(Karlstrom 1962). However, there are also anecdotal reports of B. canorus being found 150-750 m away from breeding pools in upslope habitat that is presumed to be used for foraging and/or overwintering (Mullally 1953; Mullally & Cunningham
1956; Karlstrom 1962; Kagarise Sherman 1980; Morton 1981). Thus, it would appear that B. canorus is capable of traveling relatively long distances from breeding pools over potentially hostile terrain; but how and when these toads travel upslope to find suitable habitat and how far away from the breeding pools these toads are capable of migrating is largely unknown at this time.
The purpose of this study is to determine the distance away from breeding pools that adult B. canorus are capable of traveling in order to derive an estimate of the biologically relevant size of the core terrestrial habitat required by this species
(see Semlitsch 1998; Semlitsch 2003a, b). This information is critically needed for the development of a biologically based recovery plan for this species and for the eventual designation of its critical habitat once it is placed on the Endangered Species
List. Further, the movement patterns of these toads will be analyzed to determine the home ranges of foraging adults, whether or not these toads follow particular migration corridors between habitat patches, and the diel activity patterns of emigrating and foraging adult B. canorus.
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MATERIALS AND METHODS
Study Animal
Bufo canorus is endemic to the Sierra Nevada Mountains of California from
the Blue Lakes region, Alpine Co., in the north (Karlstrom 1962) to south of
Evolution Lake, Fresno Co., near the crest of the Sierra (Karlstrom 1962; Stebbins
1966). The known altitudinal distribution limits of B. canorus within this range are
given by Karlstrom (1962) as 1,950 m (Aspen Valley, Yosemite National Park
(YNP), Tuolumne Co.) to 3,444 m (Mt. Dana, YNP, Tuolumne Co.), but he suggests
the majority of locality records should fall within the elevational range of about 2,591
m to 3,048 m. However, more recent survey efforts suggest that not only has this
toad suffered a reduction in local population density, but also that this toad may now
be restricted to habitats above 2,438 m in elevation on the west slope of the Sierra
and that this toad no longer occupies the Blue Lakes region on the northern end of its
range, which indicates that this species has suffered a reduction in distribution as well
as local population density (Martin 1990b, 1991a, b; Martin et al. 1993; Kagarise
Sherman & Morton 1993; Jennings & Hayes 1994; Drost & Fellers 1996; Jennings
1996).
The climate within this restricted high elevation portion of the Sierra Nevada
occupied by B. canorus varies considerably between years, seasons and even within a given day. Precipitation, for example, fluctuates significantly by season with more than half of annual precipitation falling as snow during January, February and March.
Less than 3% of total annual precipitation falls in the summer, usually as rain during
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brief afternoon thunderstorms, but hail and even snow flurries are not uncommon.
The temperature range in the high Sierra is reported to be between -34º and +38º C
with the coldest temperatures occurring in the winter, but summer night time
temperatures can frequently drop below freezing (Grinnell & Camp 1917; Grinnell &
Storer 1924; Karlstrom 1962; Storer & Usinger 1963). Given such high climatic
variability, it is easy to understand why B. canorus is reported to spend seven to eight
months or more in overwintering burrows during the long Sierran winter, and why in
the summer this toad is reported to be active only during the day (Grinnel & Storer
1924; Storer 1925; Wright & Wright 1933; Wright & Wright 1949; Stebbins 1951;
Mullally 1953). There are, however, a few records of B. canorus being active for a few hours after sunset during breeding congregations (Grinnel & Storer 1924; Storer
1925; Mullally & Cunningham 1956; Karlstrom 1962), but more work is needed to determine the extent of nocturnal activity by this toad.
The habitat occupied by B. canorus is generally described as relatively open wet meadows, which resemble tundra, that are scattered throughout the Sierra and are usually associated with alpine lakes or streams (Camp 1916; Grinnel & Storer 1924;
Mullally 1953; Karlstrom 1962). Within these montane meadows, adult B. canorus are reported to be common along the margins of lakes, shallow runoff streams and ephemeral pools and in close association with water where the meadow vegetation is generally deeper or more luxuriant than usual, or where there are patches of low willows which are used by the toads for cover (Grinnel & Camp 1917; Grinnel &
Storer 1924; Mullally 1953; Mullally & Cunningham 1956; Karlstrom 1962). In addition to willows, B. canorus is also reported to seek cover under surface objects
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such as logs and stones, but their preferred cover appears to be the subterranean
burrows of rodents such as mountain meadow voles (Microtus montanus) and pocket
gophers (Thomomys monticola). These burrows are thought to provide protection
from the cold temperatures at night in the high Sierra, as well as a moist microclimate
that allows toads to inhabit the drier parts of the meadow away from open water
(Stebbins 1951; Mullally 1953; Mullally & Cunningham 1956; Karlstrom 1962; see
also, Schwarzkopf & Alford 1996). However, Mullally (1953) notes the apparent
restricted movement of B. canorus near water within meadows, and Karlstrom (1962)
reports that B. canorus is rarely found more than about 90 meters from permanent
water; but rarely, according to Mullally and Cunningham (1956), are B. canorus
adults found within water after breeding, even though they are often observed beside
water.
Stebbins (1951) points out that the meadow habitats that B. canorus seems to prefer are generally surrounded by dry rocky terrain that this toad rarely, if ever, inhabits thereby restricting toads to meadow habitat. Karlstrom (1962), however, reports occasionally finding B. canorus adults in the margins of Subalpine forests during the day, and there are several reports of B. canorus being found many meters away from meadows on the steeply sloping mountainsides where the vegetation is unusually rich or in bushy willow (Salix sp.) thickets that often concentrate beside ephemeral watercourses or seepages (Mullally 1953; Mullally & Cunningham 1956;
Karlstrom 1962; Kagarise Sherman 1980). Kagarise Sherman (1980), in particular, reports adult toads traversing distances of 150-230 m upslope to reach foraging habitat and hibernacula at the bases of willows (and consequently navigate the return
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trip each spring over snow drifts). Also, Morton (1981) reports finding several
female B. canorus early in the active season, who had presumably just emerged from their overwintering burrows, 750 m from the closest major breeding site at the edge of a talus slope (near willows, pers. comm.), which was predominantly covered with snow at the time (the location of this particular hibernaculum is also suggested by
Mullally & Cunningham 1956; Kagarise Sherman & Morton 1984).
Thus, it would appear that B. canorus is capable of traveling relatively long distances from the wet meadows and permanent sources of water that these toads are believed to prefer to utilize entirely different upland habitats; but to date, no attempt has been made to quantify the migration patterns of individual B. canorus or any of the terrestrial habitat types they utilize, nor has there been any attempt to determine the core habitat needs of B. canorus. It has been found that the upland habitats of alpine amphibian species, in particular, are required for long-term population viability
(Sinsch 1988a; Pilliod et al. 2002; Bartelt et al. 2004; Schabetsberger et al. 2004;
Sztatecsny & Schabetsberger 2005), but in the case of B. canorus, land managers have been largely overlooking the upland habitats that are likely required by this species for population survival and eventual recovery because there is very little data available to suggest these animals utilize habitats other than alpine meadows, and because it is extremely difficult to locate terrestrial life stages outside the meadow habitats these animals are thought to prefer. Therefore, it is imperative to determine the extent and range of B. canorus movement patterns and habitat utilization in order to begin the development of a biologically based recovery plan for this species.
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Study Area
This study was conducted on three meadows containing ephemeral pools that have been consistently used by B. canorus for reproduction since at least the early
1960s (McCreedy pers. comm., pers. obs.) that are located within the Highland Lakes meadow complex (HLMC) (Figure 1) on Stanislaus National Forest (NF), Alpine
County, in the Sierra Nevada Mountains of California. The HLMC is located 5.9 km south of Ebbett’s Pass on State Highway 4. This region is a glacial cut valley, with a northeast to southwest aspect that appears to have been formed by the erosion of the headwall between two glacial cirques. As a result of this unique topography the paired kettle lakes, named Highland Lakes, are the headwaters of two different drainage basins separated by a moraine, with the larger northern lake draining into the
Mokelumne River Basin, and the southern lake draining into the Stanislaus River
Basin. The substrate within this valley is comprised predominately of granitic till with thin peat soil development on the valley floor.
North Pools
The first HLMC research site, north pools meadow, is located northeast of the northern Highland lake downstream from the lake out-flow (38.495° N, 119.797°W,
2,619 m). The hydrology of this meadow is difficult to characterize as it is located below the north Highland lake rock dam, which was built in 1952 to enlarge the natural lake (Albright et al. 1994) and appears to have altered the stream flow through the meadow. Based on the meadow topography, the three ephemeral breeding pools
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appear to be located in the abandoned stream channel that confluents with the continuously flowing main stream channel, the North Fork of the Mokelumne River, via an ephemeral stream that rarely flows after snow melt. The banks of the main stream channel are severely eroded along approximately 10 meters of its length due east of the breeding pools, but the channel banks are stabilized downstream by low growing willows. The main channel does, however, become incised by a couple of small erosional head-cuts farther down stream within the meadow. The vegetation of north pools meadow can be classified as predominantly a wet Nebraska Sedge class meadow (Ratliff 1982). The breeding pools within the meadow are shallow (< 0.5 m deep), typically ephemeral pools that vary considerably in depth and area depending on the rapid snow-melt and resulting sheet-flows early in the season (Figures 2 & 3), the water table of the meadow and precipitation recharge late in the season, as there is no direct stream channel inflow to the pools at this time. Thus, the longevity of the pools is dependent in large part on the depth of annual snow pack in the surrounding area and the variation in the water table of the meadow. The littoral zone of the pools, much like the rest of the meadow, is a dense sod of predominately Nebraska sedge (Carex nebraskensis), which is considered a valuable late season forage for cattle (Ratliff 1982). At one time the north pools meadow supported one of the largest breeding populations of B. canorus in the northern Sierra Nevada, but since the early 1980s this population has declined to approximately 50-100 adult toads
(McCreedy, pers. comm., pers. obs.).
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Mid Pools
The second HLMC research site, mid pools meadow, is located between the two Highland Lakes (38.490° N, 119.803° W, 2,620 m) north of the mid lakes moraine, so it is contained within the Mokelumne River Basin. Mid ponds meadow contains a series of four to seven small pools located adjacent to a spring and snow fed first order stream that flows into the northern lake on the southeast side of the meadow. The pools themselves do not directly communicate with the stream channel, but rather they receive their water inflow from snow-melt sheet-flows early in the season, the water table of the meadow and from precipitation recharging late in the season much like the north pools; but several of the mid pools have semi-stable undercut banks making them appear to be of kettle origin (Figure 4). Further, the mid pools meadow is much different from north pools meadow as it has a sunken basin within it that appears similar to a bog class meadow early in the season. The vernal pool that forms in this sunken basin usually dries up well before the end of July, but it supported breeding and maturation of tadpoles up until 1989 (McCreedy, pers. comm.; pers. obs.) and supported a very large breeding population of B. canorus in the 1960s (McCreedy, pers. comm.). The littoral zone vegetation of the five breeding pools in mid pools meadow are predominately comprised of Nebraska sedge (Carex nebraskensis), but rushes (Juncus sp.) are common in and around the pools; and this meadow also supports swamp onions (Allium validum) and mosses, which are likely present due to the increased moisture in the meadow. A large band of corn lilies
(Veratrum californicum), which is generally thought to be an indication of
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overgrazing (Menke et al. 1996), is located on the southwest side of the meadow as is
a dense willow thicket (likely alpine willow, Salix petrophila) located on the moraine slope south of the meadow. The most striking feature of this meadow is the erosional chiseling that has occurred along the edges of the breeding pools (Figure 4), and the severe erosion that has occurred along the edges of the stream banks resulting in down cutting of the stream channel of a meter or more; and like north pools meadow, this meadow has been extensively grazed by cattle in the past (see details below).
Tryon Meadow
Tryon Meadow (38.505° N, 119.801° W, 2,567 m), the third HLMC primary study site, is located 1.2 km north of north pools meadow at the confluence of three spring fed first order streams that in turn flow into the Mokelumne River. Tryon meadow is in hydrologic transition due to the severe down cutting of the stream channel running through the meadow. There were approximately six ephemeral pools located within this meadow that supported B. canorus spawning before 1990
(pers. obs.). At one of these pools in 1974 a very large breeding congregation of perhaps 24 spawning B. canorus pairs was observed (McCreedy pers. comm.), but due to the erosion of the stream channel and lowering of the water table in the meadow, this pool no longer supports successful reproduction (pers. obs.). Currently there are only three pools within Tryon Meadow supporting B. canorus spawning.
The first is a bathtub watering trough sunk into the ground on the southwestern edge of the meadow near the Wooster family barn, which supports very little associated
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vegetation (Figure 5). I have observed B. canorus depositing egg masses in and
around this trough (Figure 6), but I have rarely observed any of these tadpoles
surviving more than a few weeks, and none have survived to metamorphosis. The
second ephemeral pool is located in the middle of a Nebraska sedge meadow in the
southeast corner of Tryon meadow. There has been consistent spawning by B.
canorus in this pool for many years, but the pool has not persisted long enough for tadpole maturation since at least 1990 due to topographic changes wrought by livestock trampling (Figure 7). The third pool is an off channel pool (~2 m diameter) supporting littoral zone rushes (Juncus sp.) located on the northeastern edge of the
meadow near the Tryon family barn and cabin, which is used as a summer
“swimming hole” by children playing in the meadow. This pool is relatively
permanent due to its close association with the stream channel, and it does support a
small amount of reproduction and tadpole maturation in most years. It was the only
location in Tryon meadow where B. canorus tadpoles successfully metamorphosed in
1994, but this pool rarely produces more than a few recruits due to its colder water
temperatures and regular disturbance (pers. obs.). Much of Tryon meadow supports
dense thickets of several willow species (including lemon Salix lemmonii, Sierra S.
commutat and silver willow S. geyeriana) and Nebraska sedge class meadow patches;
but there has been a recent expansion of corn lilies (Veratrum californicum) within
the meadow since 1990, which is generally thought to be an indication of overgrazing
(Menke et al. 1996). Tryon meadow has been entirely fenced for many years now to
exclude cattle for much of the season because this pasture is grazed by the Wooster
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family horses used to wrangle the cattle on the Highland Lakes Grazing Allotment and as a late season gathering pasture for cattle (Albright et al. 1994).
Stock Grazing on the Highland Lakes Allotment
The entire HLMC has been subject to extensive grazing by sheep, cows and horses since at least the 1860s, but by 1944 sheep were no longer permitted on the allotment (Albright et al. 1994; Menke et al. 1996). With the exception of the 1995 season and possibly a few years during or immediately following World War II, the family of the current permittee, the Woosters, have grazed the Highland Lakes
Allotment (and thus the north pools, mid pools and Tryon meadows) every summer since 1941 with varying numbers of horses and about 215 cow-calf pairs (records of actual numbers are sparse) (Albright et al. 1994). Range condition and trend analyses of the Highland Lakes Grazing Allotment conducted in 1989 and again in 1991 by
Stanislaus NF biologists gave “unsatisfactory condition” scores for north pools, mid pools and Tryon meadows (Wold, pers. comm.; Albright et al. 1994). Overall, approximately 90% (562 out of 583) of the Highland Lakes Grazing Allotment primary range areas surveyed (representing 38% of the total range within the allotment) from 1989 to 1991 were found to be in the “unsatisfactory” condition category or overgrazed (Albright et al. 1994, table R-2, p. 15).
This conclusion should not be considered surprising in light of Calaveras
Ranger District range utilization records indicating that the permittee has “exceeded allowable use” in the key areas of the Highland Lakes Allotment throughout much of
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the 1970s, and has used the range “in excess of allowable use” every year from 1987
through 1994 (there are few records from the 1980s) (Albright et al. 1994). The
Stanislaus NF Land and Resources Management Plan (LMP IV-65) approved in 1991 calls for a minimum stubble height of 4 inches (or ~10 cm) at the end of the grazing season, which is significantly less than the 25-100 cm height that un-grazed Nebraska sedge (C. nebraskensis) can reach in the Sierra (Jepson 1975); but the consistent over-utilization of the Highland Lakes Allotment has left very little meadow vegetation at the end of each season. As a result of this over-utilization of the range, the 1995 Allotment Management Plan, which was approved by the Stanislaus NF
Supervisor, called for a gradual cattle “reduction” from 215 calf-cow pairs (or 645
Animal Months) in 1996 to 140 pairs (420 Animal Months) by 2001 unless “…the grazing capacity estimate is revised upward through monitoring...” and called for the implementation of a three-pasture rest rotation system where each meadow in the allotment would only be grazed two out of every three years (Wold 1995). However, the rest rotation management action was never implemented by Stanislaus NF on the
Highland Lakes Allotment, and no grazing occurred on the Highland Lakes allotment during the 1995 season due to the ~180% of average snow fall which pushed back the
“on time” or grazing start date to so late in the season that it was no longer economically feasible for the permitee to transport stock to the allotment. Thus, the entire Highland Lakes Grazing Allotment was effectively “rested” for the 1995 season, but grazing resumed in 1996 and 1997 during this study.
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Sampling
The detailed movements of adult B. canorus were determined using both radio
and thread tracking techniques. More generalized habitat occupancy and toad
movement data for all life stages were obtained by the capture of all individual toads
encountered, and in some cases by the recapture of marked individuals. All toads
used in this study were initially captured opportunistically by hand in the general
vicinity of breeding pools and meadows during population surveys and while tracking
toads. Most of the toads fitted with tracking devices were captured immediately
following the termination of individual breeding activity to obtain as complete a
picture of post-reproductive movements as possible. The point of initial toad capture
was marked with a numbered pin flag to ensure that toads were returned to the same
point from which they were captured and for mapping once the individual toad
departed the immediate area, which in some cases took several days. Toad positions
were recorded for all adult and subadult toads on base maps as well as triangulated
from fixed points in the meadows with a Brunton® pocket transit (azimuth, induction damped), 100 m fiberglass tape (Keson® open reel); and for longer distances a metric thread spool distance measurer (Hip-Chain; Topometric Products Ltd,® ±0.2%). All
positions were subsequently digitized for later analysis. For ease of field data
recording and subsequent data interpretation, base maps were generated from U.S.
Geological Survey 7.5 minute series topographic maps, aerial and satellite images.
The base maps included the habitat delineated into four major groups: meadow
habitat, which includes all the low gradient wet meadows and willow thickets within
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which B. canorus breeding pools generally occur; upland habitat, which includes
willow thickets, hanging meadows and areas of unusually lush vegetation located on
moderate to steeply sloping mountain sides that are spring and seep-watered;
lodgepole pine forest, which can include mountain hemlock (Tsuga mertensiana),
whitebark pine (Pinus albicaulis), Sierra juniper (Juniperus occidentalis) and to a
lesser extent red fir (Abies magnifica) as well as the predominant lodgepole pine
(Pinus murrayana); and water, which includes lakes, ponds, pools, rivers, streams, tributaries and ephemeral streams (where known). The dry rocky terrain that occurs above tree-line and sagebrush belts were not indicated as these areas are thought to be too dry for occupancy by B. canorus for all but short durations (Stebbins 1951) during migration to other habitats, which this study suggests was a correct assumption.
The captured toads were weighed to the nearest 0.5 g with a spring scale
(Pesola®; 50 g capacity) and measured (SVL; right rear tarsus length; parotid length;
parotid width and space between parotids) to the nearest 0.1 mm with dial calipers. A
hand-held PIT (Passive Integrated Transponder) tag reader (Trovan®; model LID 500;
range 16-20 cm) was used to scan captured toads for a tag (see, Camper & Dixon
1988; Gibbons & Andrews 2004). Toads not found to contain a tag were then
implanted with a PIT tag (Trovan®; model ID 100; 11.5 mm X 2.2 mm) under the
dorsal skin in the subdermal lymphatic sacs using a modification of the method
described by Sweet (1993: see also, Sinsch 1992b; Donnelly et al. 1994; Sinsch
1997). The Trovan® PIT tag comes pre-sterilized and individually packaged in a disposable 12-gauge needle, which is intended to be used for implantation with a
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modified syringe; but Sweet (1993) found that he could decrease injury to the skin
caused by the large bore needle and speed post implantation healing by using small
scissors to make a posteriorly-directed V-shaped 2 mm incision slightly to one side of
the dorsal midline and anterior to the sacral hinge. To reduce possible bacterial
infection, I washed the dorsal skin of the toad where the tag was to be inserted as well
as the scissors used to incise the skin with a 70% ethanol solution and a sterile gauze
pad (see, Camper & Dixon 1988). Between uses, the scissors were coated with
Polysporin® to retard bacterial growth. The PIT tag is inserted through the V-shaped nick in the skin using the implantation needle as a guide and to help maintain a sterile field. Once the tag is in place and the toad is released, the skin stretches over the sacral hump, thereby closing the V-shaped nick in the skin. To help prevent possible
PIT tag loss through the skin opening in smaller toads and to reduce secondary infection, the skin opening was closed with a single drop of Nexaband® surgical glue
(Closure Medical Co.; 2-octyl cyanoacrylate, which is a considerably different
formulation of cyanoacrylate glue than Super Glue®, methyl-2-cyanoacrylate that is known to cause tissue irritation and thermal burns during polymerization (Weissberg
& Goetz 1964; Quinn & Kissack 1994; pers. obs.)). PIT tags were only placed in toads with a SVL greater than 30 mm (Sinsch 1992b, 1997; and Sinsch 1992c, as cited in Fasola et al. 1993), but individual body weight and condition were used as a secondary criterion for determining if sub-adult B. canorus between 30 mm and 40
mm SVL were suitable for PIT tag implantation. All toads not found to be suitable
for radio or string-tracking were processed and released within 5 to 10 minutes at the
point of capture.
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Radio transmitters (Wildlife Materials, Inc.; model SOPT 2038 transmitters;
20 x 8 x 6 mm thick with a 20 cm trailing whip antenna; mounted wt. 1.8-2.1 g;
expected life, 96-117 days; frequency range, 172.000 –172.999 MHz) were attached
to toads with a body weight greater than 19 g, which limited toads to carrying
transmitters weighing ≤ 10% of their body weight (Richards et al. 1994: though
Sinsch 1988a reports toads carrying up to 17% of their body weight with little effect
on behavior), using a modification of the plastic belt technique described by Bartelt
(pers. comm., 1994; Bartelt & Peterson 2000: for a similar technique see also,
Tramontano 1997; Miaud et al. 2000; Richter et al. 2001; Muths 2003) (Figure 8a).
The belts were made from soft, flexible, surgical grade polyethylene tubing (Clay
Adams; P-50 tubing; ID=0.58 mm, OD=0.99 mm) that was fed through a passage in
the transmitter packages’ acrylic coating (Figure 8b). One end of the tubing was
fitted with a steel wire (OD=0.7 x 12 mm long) that was secured in place with
cyanoacrylate glue, with approximately 7 mm of the wire left exposed. The length of
tubing needed for a given belt was determined by wrapping the tubing, with the
transmitter in place on the belt, around the largest portion of the thighs of the toad
when the legs were extended (Figure 8c). The tubing was then cut to the indicated
length and the free end of the tubing was pushed over the exposed wire in the
opposite end of the tubing, thereby forming a ring with one end of the tubing retained
by friction alone (note that Bartelt (1994) used a barbed wire, which may result in an
increased probability of mortality should the belt become entangled in vegetation). It
was found that the abutting tubing ends could cause irritation to the ventral surface of
the toads, so the union between the tubing ends was rotated inside the passage in the
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transmitter package to reduce toad skin irritation. The tubing belt and transmitter
were then slipped over the extended legs of the toad and seated around the waist with
the transmitter resting on the dorsal surface of the animal and the antenna trailing
behind (Figure 9).
The difficulties associated with attaching transmitters to relatively small
anurans has been one of the major impediments to radio-tracking studies of this group
(van Nuland & Claus 1981), but other studies of Bufo using the same type of belt
attachment used here have found few, if any, adverse effects on the behavior of toads
(Bartelt 1994; Bartelt & Peterson 2000; Richter et al. 2001; Bartelt et al. 2004).
However, mortality due to snagging has been reported for similar belt attachment
methods (beaded chain, Rathbun & Murphey 1996; silicon tubing, Holenweg &
Reyer 2000; Teflon tubing, Waye 2001). This potential problem was mitigated
during this study, in part, by the friction fit modification of the belt attachment
method I used that allowed the escape of toads, after a brief struggle, should the
transmitter or belt become entangled; and indeed, two transmitters were found
“unbuckled” during this study, one under a rock and the other in dense vegetation.
Skin sores have been reported on the ventral surface of anurans resulting from this
and similar techniques (Bartelt 1994; Rathbun & Murphey 1996; Bartelt & Peterson
2000; Holenweg & Reyer 2000; Waye 2001). I found that rotating the union between
tubing ends into the transmitter package helped to significantly reduce irritation of the
ventral skin. Bartelt (1994) further recommended capturing western toads (Bufo boreas) every two weeks to remove any shed skin adhering to the transmitter attachment belt, which would retain sand and soil next to the skin, to prevent
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irritation and the resulting skin sores. However, I found that shed skin accumulated
on the tubing belt more frequently in B. canorus, which is known to have smoother skin with fewer epithelial tubercles than B. boreas (Camp 1916; Stebbins 1985); and the sloughed skin on a few individuals became encrusted with granite sand that eroded the ventral skin causing sores. Therefore toads were captured once every five to ten days, except for three toads in their overwintering burrows, to clean the skin and sand from the belts. Early in this study when skin sores were observed on three individuals, the affected toads were captured and treated daily with topical Bactine®
(Martin & Hong 1991) and the belts were cleaned, which aided in the healing of skin sores within 7-10 days without the removal of the transmitters from the toads.
However, Bactine® should be applied sparingly and only on individuals larger than
30 mm SVL because Bactine® contains lidocaine HCl 2.5% which can anesthetize adult toads if applied too liberally and can terminally overdose small sub-adult toads quite easily (pers. obs.). Toads were processed, radio tagged and released within 10 minutes at the point of capture and monitored closely for the first 24 hours to ensure a proper belt fit.
Toad movements were then tracked with a TRX-1000S receiver (Wildlife
Materials, Inc.) and a Yagi 3-element antenna (Wildlife Materials, Inc.; model F 173-
3FB 00456) for a mean of 45.8 (±7.4) days (range 19-71 days) with toads located at random intervals 2-5 times per 24 hours, during intensive tracking periods of 2 to 5 days out of every 14. Care was taken to minimize toad disturbance; but each time a toad was located, its behavior, weather conditions and temperature were recorded, and the toad’s location was marked with a numbered pin flag for later mapping.
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After the toad vacated the area, bearing and distance of successive toad locations were recorded using a Brunton® pocket transit (azimuth, induction damped), 100 m fiberglass tape (Keson® open reel); and for longer distances a metric thread spool distance measurer (Hip-Chain; Topometric Products Ltd,®; ±0.2%) was used. The micro- and macro-habitat was also quantified at each of the toad locations for later analysis (see chapter 3), and hourly temperature and precipitation data were obtained form an automated weather station located between the Highland Lakes (38.490° N,
119.805° W; 2,621 m) that is maintained by the California Department of Water
Resources. Radio transmitters were removed from toads before the end of the expected battery life except for the three transmitters on toads tracked into their overwintering burrows during the first year of this study. The belts of the three toads tracked into their overwintering burrows were altered so that the steel wire used to hold the tubing together was left partially exposed and notched with a file making it more susceptible to deterioration over time, thus allowing the belt and transmitter to fall off after about three to four months. The position and activity of toads in burrows was determined using a flexible burrow probe antenna (AVM Instrument Co. LTD.) and a rigid fiber-optic borescope (Olympus Inc. ®).
Detailed information on the movement patterns of toads within or between habitat patches over shorter time intervals was obtained by cocoon bobbin thread tracking. Thread bobbin trailing devices have been used on anurans in the past (Dole
1965; Grubb 1970; Seebacher & Alford 1999: see also, Heyer 1994; Lemckert &
Brassil 2000), but the thread bobbin-spools and harnesses used in these studies were too heavy and cumbersome to ever be used on a relatively small toad such as B.
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canorus. To thread track B. canorus I used a modification of the cocoon bobbin tracking method used on turtles by Wilson (1994). Cocoon bobbins (Culver Textiles,
New Jersey; 10 x 40 mm long; 1.8 g), which do not contain a spool, were wrapped in
a single layer of clear plastic wrap. Care was taken to ensure that the free end of the
thread was protruding from one end of the plastic wrap before the ends were twisted
closed. The twisted end not containing thread was twisted more tightly and then
folded over the center of a 20 mm length of heat shrink tubing (ID = 1 mm), which
had the ends crimped closed with heated hemostats. The folded-over end of the
plastic wrap was then taped to the body of the wrapped bobbin with a narrow strip of
electrical tape (0.5 x 3 cm long), thereby holding the heat shrink tubing in place at
90° to the bobbin. An “alligator clip” was then attached to the protruding end of the
wrapped bobbin package, which contained the thread, and the package was dipped in
a solution of black Plasti-Dip® that was thinned with toluene to about a 50:50 solution
(this dilution decreased the thickness of the coating thereby decreasing the overall
weight of the pouch), and then the pouch was hung by the clip to dry. Two dips in
the solution were often necessary to achieve the desired coating. Once completely
dry, the protruding plastic wrap was clipped back to the end of the bobbin, which
allowed the thread to pay out easily, and the crimped ends of the heat shrink tubing
were clipped off. The finished thread pouch weighed less than 2 g and became
lighter as the thread paid out of the pouch.
Toads to be thread-tracked were weighed and measured as above, and the
thread pouch was attached to the toads using the polyethylene tubing belt method
described above (Figure 8), with a portion of the steel wire between the tubing ends
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left exposed and notched with a file to promote corrosion and belt loss should the thread run out before the animal could be recovered and the belt removed, which occurred on two occasions. The thread pouch was largely dragged behind the toad making it very low profile (Figure 10), which reduced the chance of the thread pouch becoming lodged in toad burrows or becoming entangled in vegetation as has occurred with previous trailing devices (Grubb 1970). The toads were released within 10 minutes at the point of initial capture, and the free end of the thread was tied to the pin flag marking the point of capture. The cocoon bobbins that were used contained about 150 m of thread which can last from one to four days depending on the activity of the animal, so toads were located 3 to 5 times per 24 hours by following the thread trail to the toad. Care was taken to minimize toad disturbance, but each time a toad was located, its position was marked with a numbered pin flag that was wrapped around the trailing thread to indicate known times and locations within the thread track. Once the thread pouch was removed from the animal, the thread track was mapped, as above, and photographed to document the habitat traversed. The pin flags indicating positions where toads were physically observed were mapped independently from the thread track data, and the habitat was quantified at each pin flag/toad location in the same manner as the radio-tracked toads. This parallel mapping was used to compare the movement estimates that would be obtained from radio-tracking data and the actual movements through habitat by toads as indicated by the thread track.
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Data Analysis
The base maps, which include the general habitat types, ground survey data, tracked toad movement data, and individual toad location data were digitized using
AutoCAD® 2006, Autodesk® (v. 54.10, Autodesk Inc., San Rafael, CA) to maintain the high resolution distributional relationships between animal locations measured during this study. Movement plots, polar coordinates and home range estimates used for analysis were generated using AutoCAD®. In order to statistically analyze the spatial distribution of toads, the generated polar coordinates of toad movements were converted into vectors using simple trigonometric functions. Basic statistical analyses including t-tests, regression analyses and an analysis of covariance
(ANCOVA) were conducted using SPSS® or SYSTAT® (v. 14 & v. 8.0 respectively,
SPSS Inc., Chicago, IL).
Home range estimates for individual toads were calculated using the simple planimeter minimum area convex polygon method (Mohr 1947; White & Garrott
1990; Powell 2000). This method of home range estimation is widely criticized for its sensitivity to extreme data points and for implying that all portions of the home range generated are used evenly by study animals (see, White & Garrott 1990; Powell
2000, and references cited there in). However, for this study home range estimates will be provided with movement distance estimates to provide a general indicator of how toads move through their environment, i.e., in a zig-zag or straight line fashion, and as a method for illustrating how individual toad movements differ between the breeding period, post reproductive migration, foraging period and migration to
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overwintering sites. Home ranges are not being used in this study to provide implicit
models of toad habitat utilization, nor are they intended to imply that all of the areas
contained within the range estimates provided are utilized by individual toads.
However, I would argue that the detailed movement patterns of individual toads
gathered for this study, and in particular the movement patterns obtained by string-
tracking, greatly increase the accuracy of the range estimates.
The accuracy of home range estimates, like radio-tracking studies in general,
are dependent in large part on the number and frequency of fixed animal locations, or
“fixes,” provided to the model and the scale to which the estimate is applied. Much
of the biological data used in the development of the theoretical underpinnings for
these kinds of studies has been generated with relatively large and vagile species such
as mammals and birds over relatively long activity periods of many months or years
and on relatively large scales of kilometers or larger. The movement patterns of
relatively small, low vagility species over relatively short activity periods of only a
few months, such as those of B. canorus and other amphibian species that are
generally less than 1,000 m, are somewhat more difficult to quantify in a biologically
meaningful way (Sinsch 1990). Further, the frequency and periodicity of individual
toad location fixes were found to be extremely important for gaining a more realistic
assessment of how B. canorus interacts with its environment. However, like all studies of animal movements, there is a trade-off between the accuracy of the movement estimate and the level of animal disturbance resulting from obtaining a large number of position fixes (Powell 2000), and this is especially the case with the tracking of amphibians that necessitate the use of extremely small, low-power radio
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transmitters that are more difficult to locate in a timely manner. At some point the accuracy brought about by increasing the number of location fixes will be eclipsed by the changes in animal behavior, and thus movement patterns, resulting from the disturbance to the animal caused by obtaining the location fixes. Thus, amphibian tracking studies must balance the frequency and intensity of the tracking effort with the accuracy of the data collected.
To resolve some of these inherent problems I took a stratified approach to collecting B. canorus movement data. Fine scale movement and activity patterns were assessed using cocoon bobbin tracking devices. These devices probably provide the most accurate estimate of actual toad movements and periods of activity possible with minimal additional disturbance to individual activity patterns than would occur during intensive radio-tracking. Radio-tracking provides positional data at particular intervals, but movement data is limited to straight line distance estimates between positional fixes, and therefore may or may not represent the actual movements of the animal being studied. String-tracking (with cocoon bobbins), on the other hand, provides the same positional data as radio-tracking, but it also provides data on the actual distances traveled between fixes and information about the kinds of microhabitat used to accomplish those movements. Further, string-tracking provides information about the activity of individuals between positional fixes. Does a particular toad remain in its burrow from one positional fix to another, or does the toad forage in the area only to return to the same burrow before the next positional fix is obtained? These devices probably provide the most accurate estimate of actual
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toad movements and periods of activity possible with minimal additional disturbance to the daily activity pattern of individual toads than occurs during radio-tracking.
Diel activity patterns are particularly important for understanding the microhabitat needs of montane species such as B. canorus that inhabit environments that are hostile to their basic physiology (Sinsch 1990), but radio-tracking studies where two to three positional fixes are obtained per day offer little insight into these activity patterns. String-tracking does, however, provide insight into these activity patterns; but like all good techniques, string-tracking does have limitations beyond the extreme effort it takes to collect the data string-tracking is capable of providing.
The cocoon bobbins at the heart of the string-tracking packages used for this study only contain about 150 m of thread, which equates to about 24 to 72 hours worth of individual toad movements. Thus, the string tracked toads had to be closely monitored during the tracking period, and the toads had to be handled to change the thread pouches about every two days. This level of research intensity makes it exceedingly difficult to accomplish other research activities concurrently and virtually impossible form a logistical standpoint, so string-tracking was limited to periods of two to five days during this study.
Radio-tracking of individual toads occurred over much longer periods of up to
116 days, but unlike string-tracking, radio-tracking can be conducted with varying levels of intensity. The mathematically ideal radio-tracking study would include positional fixes at frequent regular intervals, but the logistical constraints on conducting research in isolated areas coupled with the unavoidable disturbance to individual toads makes such a design untenable for all but very short periods (e.g.
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Tramontano 1997). To minimize the disturbance to individual toads brought about by obtaining location fixes while still gathering biologically meaningful data, I stratified my approach for collecting positional information on individual toads by separating periods of intensive tracking where positional fixes were obtained two to five times a day for periods of several days with intervals of 10 to 15 days between intensive tracking periods. This stratification method was intended to maximize the amount of biologically meaningful microhabitat utilization and activity pattern data collected, while still allowing toads undisturbed periods over which to conduct much of their foraging activities and macrohabitat movements, and thus achieve a broader understanding of seasonal movements of this species. Finally, this study provides a unique comparison of the kinds of information gathered from radio-tracking studies
with actual toad movements and activity periods as is indicated by the string-tracking
data. This kind of ground proofing of radio-tracking assumptions is rare for
amphibian tracking studies (but see, Tramontano 1997; Eggert et al. 1999; Seebacher
& Alford 1999; Lemckert & Brassil 2000, for studies attempting to address this
problem).
The small sample size of B. canorus adults tracked during this study was the result of the large individual body size required to successfully carry tracking packages and by regulatory limitations. As noted earlier, the major constraint on tracking studies of amphibians is the weight of the tracking package relative to the body mass of the toad that must carry it, which should not exceed 10%. The tracking packages used for this study ranged from 1.8 to 2.1 g, which restricted tracking subjects to toads with a body mass greater than 18 to 21 g. The body mass of adult B.
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canorus encountered during this study ranged from 9 to 48.37 g with the mean weight of female toads ( x =26.49±9.38 g, n=25) being significantly greater (t24=6.281, p<0.000) than that of males ( x =20.83±4.14 g, n=51), which means that 16% of the
adult females and 23% of adult male B. canorus encountered during this study could
not be fitted with radio-tracking devises. Further limiting the pool of toads available
for tracking was the disproportional participation in breeding congregations between
the sexes and between years when the majority of adult toad encounters occurred.
This limited the pool of potential tracking subjects encountered to 3♀, 5♂ toads in
1995, 4♀, 13♂ toads in 1996 and 17♀, 21♂ toads in 1997. In total I tracked 3♀, 3♂
toads in 1995, 1♀, 4♂ toads in 1996 and 2♀, 5♂ toads in 1997, or 25% of female and
~30% of male toads encountered that were large enough to carry tracking packages. I
would have liked to have tracked a larger number of toads in 1997 when the largest
breeding congregation and thus the largest number of adult toads was encountered
during this study, but I was limited to tracking only 10 individuals by regulatory
constraints owing to the protected status of this species, and female toads proved
difficult to locate at the conclusion of breeding.
To compare the mean movement distance estimates obtained from string-
tracking and radio-tracking techniques, and to compare the mean home range
estimates obtained by the dual mapping procedure described above, paired t-tests
were performed followed by simple linear regression analyses which were then used
to examine the relationship between toad movement distance estimates and home
range estimates. Scatter plots with the regression line and 95% confidence interval
were produced for the significant relationships.
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To study the diel activity patterns of radio and string-tracked B. canorus the tracking data set was divided into diurnal (10am to 10pm) and nocturnal (10pm to
10am) periods. These time periods were selected to better encapsulate the diel changes in the thermal conditions of the microhabitats occupied by these toads than would result from a strictly “light” vs “dark” designation. The total distance traveled during each diel period was calculated for each toad and recorded along with the tracking method. Movement distances could not be clearly determined for all diel periods for every toad due to the random timing of positional fixes, but a total of 164 clearly defined diel distance measurements were calculated from the tracking data set.
Because the distance measurements were not normally distributed, a Mann-Whitney rank sum test was used to examine the differences in median values among the tracking and diel groups.
To study the dispersal distances of post reproductive B. canorus, polar coordinates (a= angle, r=straight line distance) from the nearest breeding pool center, an a posteriori defined point central to the actively used breeding pools, to a total of
171 toad locations were calculated in AutoCAD® for 139 individual toads (Appendix
1). In an effort to avoid the confounding effects of individual tracked toads using the same burrow positions for extended periods thereby violating the analytical assumption of randomly sampled toad positions, only the tracking origin point that was the result of a random animal encounter and the position in the individual toad track that was farthest from the meadow center were included in the toad distribution data set. There were also eleven toads that were recaptured at least once during the three years of this study without the aid of tracking equipment, so the positions of
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those individuals were assumed to be essentially random and as such included in the
data set, but no more than 5 ( x =1.22±0.62) locations were recorded for any one
individual.
In addition to recording the individual toad identification (PIT tag) and polar
coordinates, the sex of the individual, distributed into four sex/age classes (adult
males [3+ years], adult females [4+ years], subadults [1-3 years] and juveniles [<1
year]); date of toad capture; number of days since the start of breeding activity to date
of toad capture; site identification number (meadow); and habitat type (meadow,
upland, overwintering) were recorded in the distribution data set (Appendix 1). The
number of days since start of breeding period to capture date was used in the analysis
rather than the actual date of capture to correct for the variation in weather patterns
between years.
In an effort to ensure that the ANCOVA assumption of equal variances of the
data at all levels of factors was met before the analysis was performed on the toad
distribution data, a Levene’s test of equality of error variances was performed on the
data set. This test revealed a highly significant difference (F20,151=6.706, p<0.000) between the variances at the different levels of the model when dispersal distance was the dependant variable, so the dispersal distance variable was square-root transformed and retested. The Levene’s test was still significant (F20,151=2.360, p=0.002) after
having transformed the data, but the standardized residual plot for the square-root of
dispersal distance appeared much more uniform except for two outliers; however,
there was no biological justification to discard the two outlying data points
representing two male Yosemite toads that migrated much farther than the rest of the
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individuals during this study. Further, the normal probability plot of standardized residuals was a very close fit to the expected probability, and ANCOVA is also robust with respect to the assumption of the underlying normality of the sample (Zar
1984), so the analysis was performed with the caveat that the results should be interpreted cautiously.
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RESULTS
Toad Tracking
A total of 10 toads, 4 females ( x =68.8±3.5 mm SVL, x =36.6±6.1 g) and 6
males ( x =62.7±1.0 mm SVL, x =23.1±1.9 g), were radio-tagged during the active seasons of 1995-97 for periods of 19 to 71 days ( x =46.2±7.4) each with 7 to 49
( x =28.2±4.8) location fixes per individual toad (Table 1, see also Figure 11, Figure
12, Figure 13 & Appendix 2). The estimated total linear distance traveled by
individual radio-tracked toads ranged from 77.5 to 1,763.11 ( x =494.31±164.37)
meters with an estimated sum total of 4,943.15 meters traveled by all 10 radio-tagged
toads during this study. The simple average of estimated linear distance traveled per
day for individual toads ranged from 1.36 to 56.87 meters ( x =11.45±5.22), and the
maximum distance individual toads traveled from the tracking origin point ranged
from 31.21 to 637.06 meters ( x =201.22±53.92). Home range estimates for the entire
period toads were radio-tracked varied considerably from 441.54 to 33,869.75 m2
with a mean home range of 8,457.93 (±3,138.53) m2. Although some of the variation
in the travel distance and home range estimates may be due to the variation in the
number of days individual toads were tracked, there was no significant relationship
detected between the number of days individual toads were tracked and either the
estimated distance toads traveled or the estimated home range of toads.
A total of 11 toads were string-tracked, including 3 females ( x =63.3±2.7 mm SVL, x =22.5±1.8 g) and 8 males ( x =61.5±1.1 mm SVL, x =22.2±1.4 g),
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during the active seasons of 1995-97 for periods of 2 to 5 days ( x =3.1±0.3) each
with 3 to 9 ( x =6.18±0.68) location fixes per toad (Table 2, see also Figure 11,
Figure 12, Figure 13 & Appendix 2). The total linear distance traveled by individual
string-tracked toads ranged from 27.39 to 237.74 meters ( x =121.61±17.44) with an
estimated sum total of 1,337.72 meters traveled by all 11 string-tracked toads during
this study. The simple average of linear distance traveled per day for individual
string-tracked toads ranged from 10.32 to 79.07 meters ( x =41.87±6.08), and the
maximum distance individual toads traveled from the tracking origin point ranged
from 7.48 to 135.35 meters ( x =59.26±12.52). Home range estimates for string-
tracked B. canorus also varied considerably from 35.07 to 2,726.09 m2 with a mean
home range of 908.08 (±251.70) m2.
As discussed previously, periodic positional fixes were obtained for string-
tracked toads in the same general manner and frequency as they were obtained for
radio-tracked B. canorus, thereby allowing a comparison between the movement data and range estimates obtained by the two techniques on the same toads over the same time period (Table 3 & Figure 14). The mean of total distance ( x =128.56±17.49 m)
traveled by string-tracked toads was significantly longer than the mean of the
estimated total distance ( x =76.17±12.76 m) traveled based on simulated radio-track
data over the same period (Paired-sample t-test; t10=4.30, p=0.002). Analysis by
linear regression did however reveal a significant positive relationship (F1,9=9.55,
p=0.013, adjusted R2=0.46) between the distance traveled by string-tracked toads and
the simulated radio-tracking travel distance estimate (Figure 15), which would
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indicate radio-tracking movement estimates may be indicative of actual toad
movements for at least the intensive tracking periods where positional fixes on toads
were obtained three to four times per day. The mean home range estimate for string-
tracked toads ( x =908.08±251.70 m2) was also significantly larger than the mean
home range estimate ( x =478.39±210.63 m2) obtained from the simulated radio-
tracking data (t10=3.73, p=0.004). Regression analysis of the range estimates
obtained from string and simulated radio-tracking data also indicated a significant
2 (F1,9=34.55, p<0.000, adjusted R =0.77) positive relationship (Figure 16) that once again suggests radio-tracking may be indicative of the actual ranges utilized by toads during the intensive tracking periods. However, I will make no attempt to extrapolate this relationship since it is based on a small sample over an intensive tracking period of two to five days. Thus, string and radio-tracking data will be presented in tandem for the remainder of this chapter.
Overwintering Sites
During the 1995 season the radio transmitters were left on three toads, 1 female (F-000132F3C3, 66.5 mm SVL, 66.5 g) and 2 males (M-000132A9C9, 62.6 mm SVL, 28.0 g & M-000132E8DA, 65.0 mm SVL, 31.8 g), in the mid pools meadow area at the conclusion of the active season. All three of these toads were captured toward the end of the active season (27 September 1995, 16 August 1995 and 25 August 1995, respectively) and were fitted with transmitter packages that were attached with self-decomposing tubing-belts. The female was captured in
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upland habitat above mid pools meadow on the southeast slope of Folger Peak, whereas the two males were captured while foraging in mid pools meadow proper
(Figure 13). All three toads displayed the same movement pattern (see plots contained in Appendix 2) where the toads left what appeared to be foraging habitat to make relatively linear migrations of 71.1 to 158.23 ( x = 123.55±26.68) meters toward overwintering sites that were located at or near the margin of the lodgepole pine forest. Once in the overwintering burrows the toads made small subterranean movements for 2 to 7 days and then all perceptible movement ceased for the remainder of the tracking period and through much of the winter. The first toad to migrate to the overwintering site was male-000132E8DA, who emigrated from the meadow some time after the evening of 26 August 1995 and arrived at the edge of a small patch of forest by 16 September 1995 (Figure 17). This individual moved around in the overwintering area more than the other two toads but ceased all perceptible movement by 17 October 1995. The other two B. canorus emigrated from the meadow some time after 29 September 1995 and arrived very near the final overwintering site by the morning of 15 October 1995 for the male and by the afternoon of 16 October 1995 for the female (Figure 18). All subterranean movements of the male ceased by 17 October 1995 and by 23 October 1995 for the female. The actual timing of the migration for all three individuals likely took place over a much shorter interval than indicated above, as all three individuals moved during one of the radio-tracking rest periods; and it took two to three days to locate each of the toads in their overwintering burrows after the tracking hiatus because of the combination of the long distances traveled, depth of the overwintering burrows,
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rocky composition of the soil where the overwintering burrows were located that deflected the radio signal and the low power of the radio transmitters (transmitter range was reduced to ~25-50 meters from overwintering site). These three toads were monitored in their overwintering burrows following the regular tracking protocol until 24 October 1995. The toads were then checked for movement in their overwintering burrows for an additional 47 days each using a burrow probe antenna and a fiberoptic borescope on three occasions from 24 October until 10 December
1995, when snow had partially covered the ground (Figures 17 & 18), which confirmed their continued use of a single burrow during the winter and a lack of movement within the overwintering burrows.
The actual trigger for migration to overwintering sites may have been temperature. The temperature varied considerably during the summer 1995 active period (Figure 19), but between the end of the breeding season and 22 October, the night time temperatures only dropped to the freezing point on the 12th and 22nd of
July, 18th of August and on the 28th of September; but beginning on the 29th of
September the night time temperatures regularly dropped to well below freezing.
Further, the day time high temperatures dropped to below 15° C on 22 September and continued to decline until 28 September when the high temperature only reached 7.2°
C. The combination of decreasing daytime high temperatures with night time temperatures falling well below freezing may have triggered the two toads to seek overwintering burrows. The male toad that prematurely sought an overwintering burrow on 26 August may have been triggered by a combination of the night time
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freezing temperature on 18 August and the day time high temperatures not reaching
15° C on the 27th and 28th.
All three overwintering sites consisted of rodent burrows in dry, rocky soil located in the terminal moraine between the two Highland Lakes with an approximate elevation 1-2 meters above that of mid pools meadow proper. The overwintering sites of the two males were located at the edge of the lodgepole pine (Pinus murrayana) forest that abuts the sagebrush (Artemesia tridentata) belt that surrounds the mid pools meadow on the southwest end (Figures 17 & 20). The overwintering burrow of the female was located about 25-30 meters from the forest edge nearest mid pools meadow on the bank of a dry wash (Figure 18) 80.37 meters northeast of the overwintering burrow of male-000132A9C9.
Attempts to excavate the overwintering burrows of female-000132F3C3 and male-000132E8DA the following summer failed due to the presence of large buried boulders covering the burrow tunnel. However, the overwintering burrow of male-
000132A9C9 (Figure 20) located on the southeast slope of Folger Peak west of mid pools meadow was successfully excavated (Figure 21). The west facing tunnel entrance was a 6-7 cm diameter, slightly oval-shaped, blind-ending 130 cm long tunnel that opened to a small chamber at the end. This chamber was 35 cm below the ground surface while most of the rest of the tunnel was 25 cm deep. About half way along the north side of the tunnel was a 25 cm long blind-ending side tunnel. The tunnel and terminal chamber were moist, but not wet, and were encapsulated within lodgepole pine tree roots. There was no sign of either the radio-transmitter or the male toad in the tunnel. When the overwintering burrow was reburied, every effort
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was made to recreate the rough structure of the tunnel using rocks, bits of tree root
and compacted soil.
Toad Movement Patterns
The B. canorus tracking data was broken down into discrete range estimates
representing breeding behavior, migration from breeding sites to foraging habitats,
foraging behavior and migration from foraging areas to overwintering sites (Table 4.).
The determination of these discrete range units is somewhat subjective, but the following description of discrete range units includes general rules that were used to define these units.
Breeding range was defined as movements that took place in the breeding pools and within 2 meters of the breeding pools. The mean breeding range for string- tracked toads was 296.46±165.94 (n=4) m2 with the mean distance traveled being
99.99±30.89 meters. It should be noted that tracking packages were not attached to
toads until such time as it was believed participation in breeding activities had
concluded. This determination was much more easily accomplished with females
that tended to disperse from the breeding pools immediately after breeding activities
ended. Some of the male toads, on the other hand, remained in the pools for one to
two days after the last female had departed the breeding area, so the breeding ranges
of the four males measured during this study (Figure 22) probably represent much
larger breeding ranges than would be a typical range during the height of the breeding
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period when the majority of males were present and competing for calling sites (for a discussion of breeding ranges see, Kagarise Sherman 1980).
The post-reproductive migration range consisted of the relatively straight line movements of individual toads that began 2 meters from the breeding pools and ended when the individual was located within 2 meters of the foraging range located in upland habitat. The mean migration range (calculated as a minimum area convex polygon, see data analysis section for discussion) and distance traveled were
3,081.76±2,188.75 m2 and 266.90±116.57 (n=4) meters for radio-tracked toads and
1,174.86±573.43 m2 and 132.15±17.45 (n=4) meters for string-tracked B. canorus, respectively. The high variation in the migration ranges and their large size is a function of the directness of the path taken between breeding and foraging habitat and the long distances traveled and not indicative of the habitat area actually utilized by toads. The string-tracked toads in particular made long and relatively straight line movements from the breeding pools over short periods of two to three days; but due to limitations in the methodology, string-tracked toads could not be tracked all the way to upland foraging habitats, which is why the distance and range estimates for string-tracked toads is so much smaller than the estimates for radio-tracked toads.
However, string-tracked toads classified as participating in foraging behavior followed the same general path as radio-tracked toads that were tracked all the way to upland foraging habitats. Male-000133285CT, for example, was initially fitted with a string-pouch and switched to a transmitter midway through the breeding migration, but the initial period of string-tracking demonstrated relatively straight line movements toward upland habitats (Figure 23) very similar to the movements that
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would have been obtained from radio-tracking (Figure 14k) and was quite different from the more random movements of toads observed foraging in the meadows surrounding the breeding pools, such as female-0001DA5A76T (Figure 14c).
There were notable deviations from a straight line migration from breeding pools to upland foraging habitats. For example, three toads (F-00013263BDT, M-
00013246C0T, M-000133C20AT) deviated from a straight line path between breeding pools in north pools meadow and upland foraging habitat on the north- northwest slope of Hiram Peak to cross the North Fork of the Mokelumne River
(which is better classified as a 2nd order stream at this point) at the same point southeast of the breeding pools. This portion of the river was slower moving than much of the rest of the river and contained a small island in the middle with water moving more slowly on the shallow west side of the island than on the deeper east side. This crossing point on the river was also just upstream from an approximately
40-50 meter stretch of river channel characterized by well developed overhanging banks that were stabilized by low growing willows. The branches of these willows over-hung and extended into the river proper providing a net-like structure that the toads used to extract themselves from the swift river current that washed them downstream from the upstream crossing point. Two additional toads from the north pools breeding population also crossed the North Fork of the Mokelumne River, but these two toads (F-000132A698T & F-0001324E3CT) crossed the river along the stretch bordered with willows downstream from the crossing point described above.
The mean downriver displacement for four of the toads crossing the river channel was
20.99 (±9.03, range 4.59-46.56) meters. The string-tracks of three of the toads were
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particularly enlightening as they clearly showed the point where the toads entered and departed the river channel. Two of the string tracked toads (F-00013263BDT & M-
000133C20AT) crossed the slower and shallower west portion of the river to the island with very little downstream displacement; but once they entered the deeper, more swiftly flowing portion of the river to the east of the island they were washed downriver into the reach bordered by willows where the toads came into contact with the over-hanging willow branches on the east bank of the river where they were able to extract themselves from the water. The thread trailing in the water showed very little “looping” of surplus thread downstream from the initial point of contact with the over-hanging willows, and a nearly perpendicular line from the point of initial willow contact to the bank of the river, which was a 20-30 cm distance, and extending into the terrestrial environment. The density of over-hanging willow branches along the river margins, coupled with the string-track continuing directly into the terrestrial environment; makes it very unlikely this string-track was the result of the river current rather than the actual movements of toads. The female string-tracked toad (F-
000132A698T) that crossed the river in the willow reach downstream from the crossing point of the other toads showed a very similar river exit strategy, but when entering the swiftly moving water in the willows, the string track does not show any immediate downriver displacement as occurred on the east side of the island described above. The string-track of this individual when entering the river was largely perpendicular to the stream channel for approximately 15 cm as the track moved through the overhanging branches of the willows. Once clear of the willows the string-track displaced 4.59 meters downstream before initial contact with
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overhanging willow branches on the east side of the river. Another female B.
canorus (F-000132C94A) was observed to cross the swiftly flowing stream in Tryon meadow, but this toad was displaced downstream 71.9 meters before emerging on the far bank of the stream channel. This long distance downstream displacement is likely due to the lack of willows bordering the stream channel that were used by the toads in north pool meadow to extract themselves from the swift waters of the stream channel.
The 2nd order stream flowing through Tryon meadow has severely eroded banks due to a long history of intense grazing by horses in the meadow. As a result there are very few willows located along this stream channel and thus very few willow branches extending into the channel that could be used by the toad for extraction. All six toads were observed to cross the river/stream channel at night.
Another notable deviation from a straight line migration from breeding pools
to upland foraging habitats was observed in the string-track of male toad
000133285CT (Figure 14k & 23). This male did not cross the stream channel to the
east of the north pools breeding habitat, instead this individual traveled north
northwest to upland habitat located near the Highland Lakes road (Figure 12). A
direct line path between the breeding pools and upland habitat would have taken this
toad through lodgepole pine forest and dry rocky terrain that is likely inhospitable to
B. canorus (see, Stebbins 1951). The string-track, however, indicates that once this
toad left the wet north pools meadow, it traveled in the drainage ditch along the side
of the road (Figure 23). During the day this ditch appeared to be dry, but at night
when this toad was moving in this roadside ditch, the bottom of the ditch was moist
and even had places where water trickled along the surface. When the toad stopped
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moving for the night (some time between 3:30 am and 11:45 am) this toad sought shelter in a burrow under a rock just a few meters from the roadside ditch. At 10:30 pm (18 June 1997) this toad was found traveling in a generally northerly direction, but again this toad was traveling in the moist roadside ditch and avoiding the otherwise dry rocky terrain. The string-pouch was switched to a radio transmitter at that time as the string pouch was nearly empty, so much less detail is available regarding the remainder of this migration, but this toad was found sheltering in burrows during the day that were within a few meters of the roadside ditch. The path taken by the three B. canorus (F-00013263BDT, M-00013246C0T, M-
000133C20AT) that crossed the river at the same point east of the breeding pools also suggests that these individuals avoided dry rocky terrain during their migration to upland habitat. The radio-track of the female toad in particular shows that this animal avoided moving through not only dry rocky terrain, but also avoided the dry lodgepole pine forest habitats. When this toad did migrate through forest habitat the movement track suggests this animal used vegetated gullies, which indicate the presence of moist soil, rather than the dry barren areas on the forest floor. The radio- tracks of the other two toads are not as clear regarding the path taken between the river and the upland habitat because both toads moved from the river to upland habitat in a single night.
Some of the tracked B. canorus took on a more random movement pattern immediately after leaving the breeding pools while still in the surrounding meadows, a pattern that was more consistent with foraging behavior than directional migration behavior, so these individuals were not assigned a migration range. The foraging
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range of B. canorus was the most difficult range to clearly define as some individuals
tended to remain in relatively small areas and return repeatedly to the same burrows
(e.g., M-000133185CT, M-O001326619, F-0001333EBFT; Appendix 2); whereas
other individuals appeared to forage over a large area (e.g., M-0001324E3CT, M-
00013246C0T, F-00013263BDT; Appendix 2), but all of the foraging ranges had a
characteristic variation in the direction of movement that did not appear to be
directional as was characteristic of the migration ranges. Further, the foraging range
occurred in either meadow habitat or upland spring/seep habitat with dense
vegetation, whereas migration movements took place through a variety of habitat
types. The mean foraging range and distance traveled was 4,003.95±1,304.28 m2 and
233.37±64.22 meters (n=8) for radio-tracked toads and 429.25±223.24 m2 and
100.22±35.45 meters (n=4) for string-tracked B. canorus, respectively. The large
difference in the foraging range and distance estimates between radio and string-
tracked toads was in large part due to the fewer number of days that toads were
tracked with string pouches ( x =4.25±1.11 days) than with radio transmitters
( x =36.50±9.49 days).
The last discrete range unit was the migration to overwintering sites
previously discussed. The mean migration range of the three individuals that were
radio-tracked to their overwintering sites was 262.54±207.54 m2 and the mean
distance traveled to overwintering sites was 123.55±26.68 meters. Migration to the
overwintering sites likely took place over a relatively short period of time, much like
the migration from breeding pools to upland foraging habitat.
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Diel Activity
The distance traveled by B. canorus during diurnal and nocturnal diel periods
was obtained from the radio and string-tracking data set (Table 5). The distances
traveled by B. canorus showed no significant difference in the median distance traveled during nocturnal (7.66 m; x =19.07±3.32 m, n=75) and diurnal (6.73 m;
x =15.60±2.37, n=89) periods (Mann-Whitney, T 75,89=6142.50, p=0.883). There was, however, a significant difference in the median distance traveled by string- tracked (13.37 m; x =27.41±4.34, n=51) and radio-tracked (4.25 m; x =12.57±1.99,
n=113) B. canorus (Mann-Whitney, T51,113=5185.00, p<0.001). The relationship between string and radio-tracking techniques is to be expected, but the similarity between diurnal and nocturnal distances traveled for both tracking techniques was unexpected (Figure 24). However, many of the long distance migrations from the breeding pools to upland foraging habitat took place after dark. Further, when location fixes of adult toads in foraging habitat (both meadow and upland) were obtained after dark the toads were often found actively foraging out in the open, whereas when position fixes were obtained during the day toads were generally found in or basking at the entrance of burrows.
Habitat Types
The principal habitat type used for reproduction by B. canorus was meadows containing ephemeral or vernal pools (Figures 2, 3 & 4) that had a fairly consistent
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plant species composition with sedges (Carex sp.) dominating breeding pools, but the structure of the meadow habitat changed seasonally with vegetative growth and grazing pressure. The edges of these meadows including the margins of streams coursing through the meadows often supported dense willow thickets (Salix sp.) (the height of which depended on willow species and grazing pressure) that were often observed being used as cover by subadult B. canorus, late season metamorph toads and on occasion adult B. canorus that remained in the meadow area to forage after reproduction concluded. Again, the density of canopy created by these willow stands varied seasonally due to vegetative growth and grazing pressure. There was some indication that changes in the height and density of vegetation along the stream channel caused by stock grazing altered the suitability of this habitat type to subadult
B. canorus that were using it as cover (see, Chapter 3). Upland habitat, however, consisted of two principal types. Toads were observed most often in the first type that was characterized by dense vegetation, which was generally dominated by
Brewer lupine (Lupinus breweri) and/or willows (Salix sp.). This type of upland habitat usually occurred near springs and seeps on steep mountain slopes (Figure 25).
During the day toads were often located in either rodent burrows located on the margins of this habitat type or in burrows at the bases of willows (Figure 26). The second upland habitat type was a little more difficult to characterize as its primary feature was large granite boulders with underlying burrows that were utilized by toads (Figure 27). This second upland habitat type was more common around north pools meadow and generally occurred near the upland habitat characterized by dense vegetation. I suspect this second upland habitat type may represent diurnal refugia
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used by adult B. canorus to increase body temperature (whereby the boulders and rocks act as heat banks in the latter summer and early fall when air temperatures become more variable) followed by nocturnal foraging in the nearby dense vegetation habitat type, but more studies of toad movements within these upland habitats are needed before firm conclusions can be drawn. A more detailed analysis of the quantified habitat data recorded during this study can be found in chapter 3.
Dispersal Distance
The radio and string-track data provide a good assessment of the distance away from breeding pools that adult B. canorus are capable of traveling; but in order to provide a more accurate estimate of the biologically relevant size of the core terrestrial habitat required by this species, a more complete analysis of the dispersal distance from center of breeding pools by each of the B. canorus sex/age classes was conducted on the complete data set including the general habitat type in which toads were found for all B. canorus captured during this study. A preliminary ANOVA revealed a significant difference in dispersal distance between the three study meadows (F2=7.164, p=0.001), but pairwise comparisons reveled that only Tryon
meadow was significantly different from the other two meadows and that there was
no significant difference between dispersal distances of North Pools meadow and Mid
Pools meadow. Since there was only one toad tracked in Tryon meadow, the
breeding population was much smaller than either of the other meadows and the
survey effort was much less in Tryon meadow than it was for the other two meadows,
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it was determined that the observed significant difference was likely due to the unequal sampling effort. For this reason the data from all three meadows was pooled for the final analysis, which also simplified its interpretation.
An ANCOVA was performed on the square-root transformed dispersal distance of captured B. canorus with the number of days since the start of the breeding period as a covariate (Table 6). As one would expect, there was a positive correlation between the distances toads dispersed from the breeding pools and the number of days since breeding took place. There was not, however, any indication that days since breeding interacted with the sex class and/or habitat type to significantly alter the dispersal distance of toads, so these non-significant interactions were eliminated from the model. The sex class of toads did have a highly significant effect on dispersal distance (Figure 28, Table 7 & 8), but there was no significant difference between dispersal distances of adult male ( x = 80.02±14.08 m, range 3.15-
657.44, n= 74) and adult female toads ( x = 77.04±12.49 m, range 2.61-279.45, n=
40). The dispersal distance of adult toads was significantly greater than that of both subadult ( x = 61.12±11.91 m, range 2.22-257.39, n= 37) and juvenile ( x =
33.97±5.07 m, range 6.56-66.27, n= 21) toads, but there was no significant difference between the dispersal distances of subadult and juvenile toad sex classes. It should be pointed out that it is exceedingly difficult to locate toads in upland habitat without a transmitter, and subadult toads were too small to be fitted with transmitters; but despite that fact there were five subadult toads located in upland habitat during this study, which suggests that subadult B. canorus may use upland habitat more than this study was able to determine. Further, the range of subadult dispersal distances is quite
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similar to the dispersal distance range of adult females, whereas the dispersal distance
range of juvenile toads falls completely within the bounds of the meadow habitat
(<100 m). The ANCOVA also showed a significant difference between the means of
dispersal distances of toads located in the three habitat types (Figure 29, Table 9 &
10). The mean dispersal distance of toads found in meadow habitat ( x = 39.26±2.89
m, range 2.22-185.59, n= 148) was significantly smaller than the mean dispersal
distance of toads found in upland habitat ( x = 265.93±29.88 m, range 106.34-657.44,
n= 21), but there was no significant difference between the mean dispersal distances
of toads found in meadow habitat and those found in overwintering burrows ( x =
194.31±27.55 m, range 141.77-234.96, n= 3). The mean dispersal distance of toads found in upland habitat was also significantly different than the mean dispersal distance of toads located in their overwintering burrows. In summary, the mean dispersal distance from the breeding pool center to toads found in their overwintering burrows was intermediate to the mean dispersal distances of toads found in meadow habitat and toads found in upland habitat, but there was no significant difference between the mean dispersal distance of toads found in meadow habitat and that of toads located in their overwintering burrows.
Core Habitat
The most useful way to define core terrestrial habitat required by a particular amphibian species from a land management perspective is to establish a circle around an easily identified central point that is biologically meaningful for the species in
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question and incorporates all habitat types utilized by that species to successfully
complete its life cycle. In the case of B. canorus the most easily identified biologically meaningful habitat type is the breeding pool, hence the reason the point from which all the dispersal distances were measured during this study was defined as the center of the actively used breeding pools in a given meadow. It then becomes a question of how to determine the size of the core habitat utilized by this species, or the radius of the circle centered about the breeding pools that will encompass the core habitat.
The commonly used metric for delineating core habitat is the 95% confidence limit for the dispersal distance of individuals in the population (Semlitsch 1998), but this is not quite as straightforward as it might seem. The habitat needs of individuals within a given population could be very different between sex/age classes and/or periods of activity (i.e. breeding vs. foraging habitat), so establishing the core habitat needs of a population based on a random sample, especially when the sample is biased toward meadow habitats where individuals are more easily located, could greatly underestimate the core habitat needs of the species in question. In the case of
B. canorus this study found significant differences in dispersal distances between sex/age classes and the habitats they utilized (see above), so there are a variety of ways the dispersal distances of a given population could be determined based on sex/age class and/or habitat type (Table 11). A dispersal vector plot (Figure 30) visually illustrates the problem of using the mean ( x =69.64±7.27 m) and upper 95%
confidence interval (83.99 m) for the dispersal distance of all B. canorus captured
during this study. A distance of 84 meters would not even encompass the entire
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meadow habitat (Figure 31) utilized by this species let alone the upland habitat
utilized by subadult and adult B. canorus, but then most of the adult toads were captured in or near the breeding pools during or shortly after the breeding period when they are most easily observed. There were several adult B. canorus that remained in the meadows throughout much of the active season, so meadow habitat is utilized by adults throughout the active season, but the upland habitat and overwintering sites would not be protected if the upper 95% confidence interval of mean dispersal distance for the entire study sample was used to delineate the core habitat. However, a probability plot of the expected fraction of the B. canorus population contained within a given distance from the breeding pools demonstrates that approximately 95% of the population is contained within 350 meters of the breeding pools (Figure 32).
Another way to look at dispersal distance and core habitat is to examine the dispersal distances of the different sex classes two-dimensionally and assign 95% confidence ellipses to each sex class (Figure 33; Table 11). The 95% confidence interval for dispersal of juvenile toads (44.55 m) as well as the maximum juvenile dispersal distance (66.27 m) are <100 meters and therefore contained within the meadow habitat. The subadult dispersal confidence interval (85.27 m) is more like that of all the adults combined (98.99 m) with approximately 260 meters being the maximum dispersal distance of sudadults, which encompasses some of the available upland habitat (Figure 31). The adult female confidence ellipse is more directional than that of the other sex classes, which is likely due to the availability of upland habitats relative to the breeding meadows being studied, but an approximately 300
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meter radius circle (95% CI=294.83 m) would encompass the core habitat needs of
female B. canorus sampled during this study. The confidence ellipse for the adult male B. canorus encountered during this study is the largest of any of the sex classes at 300 to 450 meters (95% CI= 444.76 m) and like the females is somewhat directional, which is largely due to the two males that traveled approximately 650 meters from their respective breeding pools to share the same upland burrow/habitat north of North Pools meadow. The sharing of burrows by adult B. canorus in upland habitat seems to be common as three additional upland burrows, located northeast of
North Pools meadow, were found to contain 2 to 4 individual toads in the same burrow at the same time on several different occasions during this study, suggesting that adult toads may congregate in these limited upland habitats rather than dispersing widely in upland habitat.
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CONCLUSIONS
Data regarding the movements of B. canorus previous to this study were very
limited. Much of the available data was restricted to repeated observations of
individual toad locations in meadows containing breeding pools (Grinnell & Storer
1924; Mullally 1953; Mullally & Cunningham 1956; Karlstrom 1962; Cunningham
1963; Kagarise Sherman 1980). The natural conclusion from these studies was that
B. canorus is largely restricted to meadow habitat because very few toads were found outside meadow habitat. To date there has been only one study attempting to follow the movements of individual B. canorus using tracking devices (Karlstrom 1957), but that study met with limited success and was also restricted to meadow habitats owing to the technical difficulties, such as short tracking range, associated with using radioactive cobalt tags. There have been, however, incongruous reports of a few B.
canorus being found 150-750 m away from breeding pools in upslope habitat that is presumed to be used for foraging and/or overwintering (Karlstrom 1962; Kagarise
Sherman 1980; Morton 1981; Kagarise Sherman & Morton 1984), but the technology was not available to reliably follow the movements of these relatively small toads until the early 1990s. This study, which for the first time used miniaturized radio transmitters to track this species, found that adult B. canorus are capable of traveling up to 657.44 meters ( x = 278.60 m) from breeding pools to upland foraging habitat.
This distance is well within the longest dispersal distance from breeding pools (750
m) previously reported for this species (Morton 1981), but this study found that
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upland habitats are commonly used as foraging habitat by adult B. canorus, and that
such relatively long distances can be traversed in only a few days.
Previous studies have also suggested that post-reproductive B. canorus had
fairly restricted home ranges of perhaps tens of square meters (Mullally &
Cunningham 1956; Mullally 1953). In contrast, this study found that the mean total
home range for B. canorus is 8,457.93 square meters, which is considerably larger than that previously suggested. Even the more restrictive mean (post migration) foraging range of 4,003.95 square meters determined for radio-tracked B. canorus during this study is many times greater than the previously suggested home range for this species. There are many problems associated with such home range estimates
(White & Garrott 1990; Powell 2000), but it is interesting to note that this study found a linear relationship between actual distance traveled and the size of the home range estimate determined by intensive radio-tracking over short periods of just a few days even though radio-tracking significantly underestimated the actual movements of toads within habitat patches. Obviously it is unknown if the linear relationship between intensive radio-tracking and actual toad movements will hold up for an entire active season. It likely will not because the majority of the string-tracking and radio-tracking comparison occurred during the post-breeding migration period when toad movements tended to be more linear; but there is sufficient data to conclude that
B. canorus has a significantly larger (4,000-8,000 m2) home range than the tens of
square meters previously reported.
The string-tracking technique appeared to provide a fairly accurate record of
individual toad movements, but is limited to short tracking periods of a few days by
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the mechanics of the technique and the labor intensive nature of recording the
movement data. The radio-tracking technique, on the other hand, permits the tracking
of individual toads for much longer periods of up to 115 days during this study, but
the accuracy of the movement data is subject to the frequency of animal location
fixes. The more times the location of an animal is determined or fixed over a given
period of time, the more accurate the estimate of actual animal movements will be;
but, of course, the more frequently an animal is located, the more intrusive the
technique will be and the more likely the animal’s normal behavior will be altered.
Thus, the accuracy of radio-tracking data, or the number of times the location of a
toad is fixed in a given day, must be balanced with the potential for alteration of toad
behavior (White & Garrott 1990; Heyer et al. 1994; Powell 2000). For this study
radio-tracked toads were located at random intervals 2-5 times per 24 hours, but only
during intensive tracking periods of 2 to 5 days out of every 14. The stratified design
for obtaining location fixes when tracking B. canorus during this study was intended to provide a compromise between individual toad disturbance and the need for detailed movement data, but future tracking studies should include more emphasis on nocturnal (vs. diurnal) positional fixes to better assess periodicity of behavioral activity, with string-tracking being an important component of such future studies.
Many of the past studies of B. canorus activity report this toad being active diurnally (Grinnell & Storer 1924; Stebbins 1951; Mullally 1953; Stebbins 1954;
Mullally & Cunningham 1956; Karlstrom 1962; Kagarise Sherman 1980; Stebbins
1985). However, this study found much evidence to suggest that B. canorus conducts much of its post-reproductive activity at night and that many of the long range
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migrations took place nocturnally. This study was primarily designed to examine
dispersal distances and general movement patterns rather than diel movement
activity, so many of the location fixes were collected during the day, which further
biased the sampling toward diurnal activity; but even so, this study found that toad
movements were largely equivalent between diurnal and nocturnal periods. From
empirical evidence it would appear that B. canorus adults spend much of the diurnal period basking to increase body temperature just outside burrows, into which toads can easily retreat for cover and/or for thermoregulation (Mullally 1953; Mullally &
Cunningham 1956; Karlstrom 1962), but observations during this study suggest that much of the foraging activity and long distance migrations appear to take place at night. The stomach contents of adult B. canorus (Grinnell & Storer 1924; Mullally
1953; Wood 1977; Martin 1990a, 1991c) would appear to support this hypothesis as many of the insect species reportedly consumed by adult B. canorus tend to be more active nocturnally and would not tend to be consumed diurnally in the ambush predator fashion subscribed to this species (see, Kagarise Sherman & Morton 1984).
Bufo canorus does opportunistically ambush prey when basking during the day (pers. obs.; and above), but I suspect much of their food intake is the result of active nocturnal foraging. However, more studies regarding the feeding habits of B. canorus and their diel activity are needed before firm conclusions can be drawn.
The cold temperatures during the breeding period, which begins during snow melt, are most likely responsible for the clearly observed diurnal activity of B. canorus early in the active season when many of the past major studies of B. canorus took place (e.g., Grinnell & Storer 1924; Mullally 1953; Mullally & Cunningham
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1956; Karlstrom 1962; Kagarise Sherman 1980). Further, adult toads basking outside
burrows during the day are relatively easy to locate and approach, whereas adult
toads foraging in lush meadow or upland vegetation at night are extremely difficult to
locate even with attached tracking devices. It is, therefore, not surprising that
previous to this study B. canorus was considered to be largely diurnal. A study more focused on diel activity patterns for this species needs to be conducted with particular attention being paid to air and toad body temperatures.
The breeding and meadow habitats utilized by B. canorus have been well described in the literature for some time (Grinnell & Storer 1924; Stebbins 1951;
Mullally 1953; Stebbins 1954; Karlstrom & Livezey 1955; Mullally & Cunningham
1956; Karlstrom 1962; Kagarise Sherman 1980; Kagarise Sherman & Morton 1984;
Martin 1991c), and there have been some suggestions regarding the location of overwintering burrows and that adult B. canorus may use upland habitat (Karlstrom
1962; Kagarise Sherman 1980; Morton 1981; Morton 1982; Kagarise Sherman &
Morton 1984); but this study is the first to report the extensive utilization of upland habitat by B. canorus and the first to describe confirmed overwintering burrows utilized by this species. Further, this study provides evidence that migration corridors between meadow and upland habitat consisting of moist microclimates are utilized by this species and may be important habitat components that are in need of protection in addition to the need for the protection of breeding, foraging and overwintering habitats.
The movement patterns of adult B. canorus showed fairly concentrated travels in breeding pools during breeding congregations, followed by relatively sudden
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directional migrations to foraging habitat where the toads engaged in a more random
movement or foraging pattern for the majority of the active season. Foraging habitat
consisted of two types: meadow habitat surrounding breeding pools that are generally
closely associated with willows, which has been reported previously (Grinnell &
Camp 1917; Grinnell & Storer 1924; Mullally 1953; Mullally & Cunningham 1956;
Karlstrom 1962), and previously unstudied upland foraging habitats that are located
in the lush vegetation near seeps and/or springs on the steeply sloping mountain sides
above the breeding meadows that are dominated by willow thickets and/or lupine
stands. The majority of adult B. canorus in this study migrated to this second type of
habitat, and some individuals, particularly those from north pool breeding pools,
inhabited burrows under rocky outcroppings near the lush vegetation of seeps and/or
springs. This habitat type is considered to be an extremely productive component of
alpine ecosystems (Erman 2002), which is likely why B. canorus seeks out upland habitat; but this habitat is also extremely susceptible to damage by stock grazing and considered one of the most threatened habitats in the Sierra Nevada (Ratliff 1982;
Erman 1996). Such upland terrestrial habitats are considered to be of paramount importance in the protection of amphibian species (Dodd 1996; Madison 1997; Dodd
& Cade 1998; Semlitsch 1998; Lamoureux & Madison 1999; Semlitsch 2000; Richter et al. 2001; Biek et al. 2002; Semlitsch 2002; Vonesh & De la Cruz 2002; Semlitsch
& Bodie 2003; Semlitsch 2003b; Schabetsberger et al. 2004; Trenham & Shaffer
2005) and thus must be considered part of the core habitat needs of B. canorus that must be protected in addition to the breeding habitat if populations of B. canorus are to remain viable.
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The location of B. canorus overwintering sites has been suggested in the past
based on anecdotal observations (Kagarise Sherman 1980; Morton 1981; Kagarise
Sherman & Morton 1984), but this study is the first to document overwintering sites
actually utilized by B. canorus. Important features of these sites would appear to be
the rocky soil in which the abandoned rodent burrows occur and their location on the
border of forest habitat. Forest habitat probably represents moist soil conditions that
would prevent desiccation of toads in burrows but not wet conditions that would act
to conduct the cold temperatures, thereby reducing the insulative properties of the soil
(Grinnell & Storer 1924; Mullally & Cunningham 1956; Karlstrom 1962: see also,
Tracy 1976; Campbell & Norman 1998). By no means am I suggesting that these
overwintering sites are the only habitats utilized by B. canorus for overwintering based on a sample size of three adult toads, but clearly this habitat type is much different than the overwintering burrows at the bases of willows previously suggested. The overwintering sites observed during this study were intermediate in distance to upland and breeding habitats. It could be that these overwintering sites were those of individuals that were participating in breeding activities the following season with other overwintering sites located closer to foraging habitat that are utilized by individuals not participating in breeding the following season (i.e., why traverse down-slope only to traverse back up-slope again to return to foraging habitat?). Studies of other toad species have found a similar tendency for fall migration to overwintering sites, which are closer to breeding pools than the upland foraging habitat, that serve to gather breeding individuals closer to breeding sites,
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thereby decreasing the spring pre-spawning migration distance (Heusser 1967, as cited in, Sinsch 1988b; Sinsch 1990; Denton et al. 1997).
This study is different from previous studies of B. canorus ecology in that it documented individuals utilizing upland habitat for foraging as well as meadow habitat for foraging, and demonstrated that individuals foraging in different habitats still utilized very similar overwintering sites (i.e., individuals leaving wet meadows and spring habitats for drier forest habitats). The use of forest habitat for overwintering was originally suggested by Karlstrom (1962) and has been observed in other amphibian species (Bosman et al. 1996; Lamoureux & Madison 1999;
Holenweg & Reyer 2000). In studies of other species, individual amphibians were found to move closer to breeding sites for overwintering to presumably decrease the early season migration (Sinsch 1988a, 1990, 1992a), a pattern which describes the overwintering burrow of the female during this study that was foraging in upland habitat. However, the two males tracked into overwintering burrows during this study actually moved farther away from wet meadows where breeding pools were located and where they were foraging to overwinter in drier forest habitats that were otherwise not utilized. This behavior suggests that some factor other than decreased breeding migration distance may be involved in the selection of overwintering habitats. For example, Bosman et al. (1996) suggest that overwintering sites of B. bufo are selected based on vegetation and substrate characteristics rather than probability of survival, which may also be the case for B. canorus.
Migration between breeding habitat and foraging habitat and foraging habitat and overwintering habitat appeared to be directional in nature and to occur over
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relatively short periods during this study, which is consistent with the findings of
movement studies on other Bufonid species (Sinsch 1988b, 1991, 1992a; Kusano et
al. 1995; Muths 2003; Bartelt et al. 2004). There was very little observed deviation
from relatively direct movements to upland habitats during the current study, with
notable exceptions for avoiding major obstacles such as fast moving stream channels
and, where data is available, to remain in migration corridors with a moist
microclimate such as ephemeral washes or channels. Overall the migrations observed
during this study took place over relatively short periods of less than a few days, with
several toads during this study migrating over 600 meters in 24 to 48 hours, and much
of the migratory movements took place nocturnally.
A key conclusion of this study is that B. canorus is not restricted to small
ranges in meadow habitats as previously supposed, and that, in fact, this toad utilizes
several different habitat types for different aspects of its life history that can be: 1)
quite distant from meadow breeding pools, 2) cover relatively large habitat areas, and
3) may vary considerably with toad age, sex, diel activity periods and/or seasons.
This study also demonstrates that upland habitat, which is usually associated with
dense vegetation surrounding seeps and springs, is a critically important habitat
component for adult and subadult B. canorus.
The final and most important question to be answered by this study is, “What is the core habitat utilized by B. canorus that is in need of protection for continued population viability?” As previously pointed out, there are a number of ways one could define the core habitat needs of amphibian species, and a number of studies have suggested different generalized core habitat protection zones for amphibians
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(30-100 m along streams, Rudolph & Dickson 1990; McComb et al. 1993;
deMaynadier & Hunter 1995: 100-500 m along water courses, Dubois 1991: 600 m
from water's edge to contain 83% of amphibians, Dodd 1996: 164 m from wetland
edge to encompass 95% of salamander populations, Semlitsch 1998: core terrestrial
habitat for frogs 205-368 m from wetland edge, Semlitsch & Bodie 2003). However,
in order to define the biologically relevant core habitat needs of a particular species,
all of the habitat utilized by the species, as well as its migratory capacity, must be
contextualized in relation to the different age and sex classes to obtain biologically
meaningful protection zones (Semlitsch 1998, 2002; Semlitsch 2003a, b; Semlitsch &
Bodie 2003). A survey of Bufonid migration distances from breeding sites (Table 12)
suggests that the proposed generalized amphibian habitat protection zones may
underestimate the core habitat needs of relatively vagile toads.
In the case of B. canorus the breeding pool habitat in meadows has been
clearly defined and is easily identifiable, but there are reports of B. canorus breeding
in the margins of lakes (Stebbins 1951; Mullally 1953; Stebbins 1954; Cunningham
1963; Stebbins 1966, 1985) that may have been more prevalent in the past before the
introduction of non-native fish into the Sierra (see Chap. 1) and may be important
habitat for long term species survival under extended drought conditions. However,
ephemeral pools in meadows are clearly the predominant breeding site utilized by B.
canorus today. The breeding pools are important for not only breeding and egg deposition but also for larval maturation and metamorphosis, so the breeding pools are utilized throughout much of the active season. Once metamorphosis is complete the newly metamorphosed toads remain within approximately 10 meters of the
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breeding pools for the remainder of their first season, with the muddy shoals exposed by the decreasing depth of the ephemeral pools being particularly important habitat for individuals having just completed metamorphosis (Karlstrom 1962; Kagarise
Sherman 1980; pers. obs.). Anecdotal observations suggest that these young toadlets spend their first winter in burrows at the bases of willows in the meadows immediately surrounding the breeding pools (Kagarise Sherman 1980; pers. obs.).
The subadults spend much of the second, and in some cases part of the third, season of life in the meadow habitat surrounding the breeding pools, but these individuals appear to prefer taller, >18 cm meadow vegetation with a particular affinity for low growing streamside willows (see, Chap. 3; pers. obs.). Again, anecdotal observations suggest that juvenile toads may overwinter in the meadow near the bases of willows, but observations during this study suggest that subadults migrate from the meadow habitat to upland habitat some time during the second or early third active season where it appears they remain through maturation.
Once B. canorus become adults the sexes appear to utilize the habitat in different ways. For example, the majority of adult females appear to spend much of the active season in upland habitats except for the few days spent breeding every two to three years (Kagarise Sherman 1980). Adult females, particularly younger individuals, have been observed in meadow habitats well after the breeding season
(pers. obs.), but when these relatively few toads are found they are usually found in close association with willow thickets that resemble upland habitat rather than in open meadows. It should be noted that for this study, the tracking of most of the females began near the breeding pools shortly after the conclusion of individual
154
breeding activity, so with one exception, this study did not examine the movements of
females not participating in breeding activities during a given season. The one
tracked female that was not captured in breeding habitat was captured in, and tracked
from, upland foraging habitat into an overwintering burrow. This overwintering
burrow was located in a position intermediate between the breeding pools and upland
foraging habitat. It is presumed that this female was going to participate in breeding
activities the following season (i.e., females breed every 2-3 years, Kagarise Sherman
1980; Morton, 1982), and was thus moving to an overwintering burrow located closer
to the breeding pools. On the other hand, females that participated in breeding during
a given season may not migrate to an overwintering burrow located far away from the
upland foraging habitats they seem to prefer. Such a scenario would explain the
observation of adult female B. canorus emerging high up on mountain slopes well away from breeding pools shortly after snow melt (Morton 1981).
The adult male B. canorus, on the other hand, are much more diversified in their habitat utilization. Some of the males tracked during this study remained in meadow habitat for foraging throughout the active season, while other males immediately migrated from breeding pools to upland habitat where they remained for the remainder of the active season. It is unknown if the males have an individual preference for a particular habitat type or if other external factors, such as body condition, play a role in deciding whether to expend the energy to migrate to upland habitat or to remain in the nearby meadow habitat for foraging. Two of the males remaining in meadow habitat for foraging were tracked to overwintering habitats at the edge of forest habitat intermediate to upland and breeding habitat, which suggests
155
that meadow habitat may not provide suitable conditions for overwintering adult
toads. It is unknown if males foraging in upland habitats utilize the same
overwintering habitat as males foraging in meadow habitat, but considering that the
upland female migrated to the same overwintering habitat type near the forest edge, I
think it is reasonable to assume that upland foraging males may migrate to forest edge
habitat for overwintering to be closer to the breeding pools for an early arrival in the
breeding pools the following season (see, Heusser 1967; Sinsch 1988b & 1990;
Denton et al. 1997).
It is clear that breeding pools need protection to ensure recruitment to the
adult population, and efforts to protect meadow pools from grazing impacts such as
topographic changes, siltation, bacterial and nutrient pollution, compaction, changes
in plant community composition, channel incision and the resulting lowering of water
tables that ultimately leads to desiccation of meadows and breeding pools (Meehan &
Platts 1978; Stephenson & Street 1978; Kauffman et al. 1983; Kauffman & Krueger
1984; Bohn & Buckhouse 1985; Odion et al. 1990; Armour et al. 1991; Platts 1991;
Armour et al. 1994; Dudley & Dietrich 1995; Herbst & Knapp 1995; Kattelmann &
Embury 1996; Menke et al. 1996; Flenniken et al. 2001; Calhoun & Hunter 2003;
Semlitsch & Rothermel 2003; Derlet & Carlson 2006) have been initiated. In
Yosemite National Park stock grazing has been completely restricted from meadows containing B. canorus breeding pools (Tollefson, pers. com.), but thus far the Forest
Service has restricted its protective measures to the breeding pools proper and the area immediately surrounding them, which does little to reduce long-term grazing damage to the stream channel (such as lowering of the meadow water table) and in
156
turn hastens the drying of breeding pools, which then severely reduces or even
eliminates annual cohort survivorship (pers. obs.). Nor do the Forest Service
protective measures prevent siltation of breeding pools or the inflow of bacterial and
nutrient pollution which likely reduces the growth and/or survivorship of larval toads
(pers. obs.).
Larval amphibians are often found in ephemeral pools that cannot sustain
predators that would otherwise become established in permanent pools. However,
larval amphibians are then challenged to complete metamorphosis before the
ephemeral pool dries up (Beebee 1996; Semlitsch 2002; Semlitsch 2003a). In the
case of B. canorus, which occurs at high elevation and thus experiences a short active
season, larval forms are under acute pressure to complete metamorphosis before
snow-melt-fed ephemeral pools dry up (Karlstrom 1962; Kagarise Sherman 1980),
and therefore, even a slight lowering of the meadow water table due to stock-grazing
impacts (see, Fleischner 1994; Trimble & Mendel 1995; Kattelmann & Embury 1996;
Belsky et al. 1999) can have a dramatic effect on the survivorship of larval toads.
Thus, to truly protect B. canorus breeding pools and recruitment to the adult
population, the entire meadow surrounding the breeding pools and the associated
stream channels must be protected from grazing impacts, or the breeding pools will
not persist long enough for toad larvae to complete metamorphosis and the local B.
canorus population will in time become extinct due to lack of recruitment to the adult population (e.g., Beebee 1996; Semlitsch 1998; Semlitsch 2003a; b; pers. obs.).
The entire meadow habitat area, including the willow thickets, must also be
protected throughout the active season because this habitat is used extensively by new
157
metamorph, subadult and even some adult toads for foraging throughout the entire
active season; and meadow habitat is used for overwintering by new metamorph and
subadult toads (Kagarise Sherman 1980; pers. obs.). There is, therefore, no period of
time during the year that alpine meadows containing B. canorus breeding pools can
be grazed without having some impact on either the core habitat of B. canorus or the
survivorship of larval, subadult and adult forms. Direct trampling of both adult and
subadult B. canorus by grazing stock has been observed on many occasions (Martin
1990b, 1991a & b; pers. obs.; Buckley pers. com.), but it is virtually impossible to gauge the extent of the direct impact on the local B. canorus populations as the very
act of trampling tends to bury the evidence of toad mortality. However, on one
occasion I observed the direct mortality of approximately 60 metamorph and subadult
B. canorus (Figure 34) due to trampling after approximately 25 cattle were driven across a stream channel bordered by low growing willows in the north pools meadow.
An additional 20 individuals were found buried alive in cow fecal matter, individuals that presumably would not have survived without intervention (Martin 1990b,
1991b). The deep hoof prints left behind by the cattle probably had the greatest impact on survivorship, as these deep hoof prints, some of which were 10-20 cm deep, acted like pitfall traps from which the new metamorph and in several cases even the subadult toads could not escape, resulting in death by desiccation and/or exposure. Further, the act of grazing alters meadow plant communities and decreases vegetation height, likely affecting the suitability of the habitat for B. canorus (see,
Chap. 3).
158
The three overwintering sites observed during this study were located in forest
edge habitat. High-elevation forest habitat in the Sierra Nevada is largely immune
from logging due to the slow growth and relatively small size of lodgepole pine trees
as well as their relative unsuitability for lumber. Forest edge habitat is however
utilized by cattle, not for foraging but for escaping the hot afternoon temperatures at
high elevation by congregating in the shaded forest edge habitat utilized by B.
canorus adults for overwintering. It is unlikely that the presence of cattle in this habitat results in direct mortality of toads, but the cattle are quite capable of collapsing the abandoned rodent burrows utilized by B. canorus for overwintering. It
is unknown if these overwintering burrows are used repeatedly by toads, nor is it
known how fast new burrows suitable for overwintering are created and subsequently
abandoned by rodents, so it is impossible to determine at this time the extent of
impact cattle have on overwintering sites. Thus, the prudent course of action with
regard to the functionally Threatened Species B. canorus is to restrict cattle from the
forest edge habitat, thereby eliminating any possible impact until such time as long-
term studies of B. canorus overwintering habitats can be conducted.
The upland habitat utilized by most adult and by at least some subadult B.
canorus for foraging and possibly for overwintering by non-reproductively active adults has not received any protection from grazing or other impacts, as this habitat has been viewed as unimportant relative to breeding habitat. Current Forest Service policy is to protect B. canorus breeding habitat only (USDA 2004), based on the
assumption that “…breeding habitat is the area of critical concern… the risk to toads
is low outside of breeding habitat primarily because stock are not in or near toad
159
habitat for the vast majority of the year...” (Tenpas & Glazer 2007, p. 38). However,
this study found that adult B. canorus, in particular, aggregate in relatively small
upland habitats and even share the same burrows. The upland habitat utilized by B.
canorus, which is usually associated with springs and/or seeps, is very fragile and extremely susceptible to grazing impacts (Ratliff 1985), and grazing is considered to be the greatest threat to upland spring species (Erman 1996). While it is true that livestock often gravitate toward low-gradient riparian and wetland habitats because of the ease of access, superior forage and readily available water (Kie & Boroski 1996;
Calhoun & Hunter 2003), livestock do not exclusively graze these areas. Further, when exclosures are erected around meadow and/or stream habitat to protect B.
canorus breeding pools or other imperiled species (what the Forest Service terms
“resources”) cattle then gravitate to the much smaller area in upland habitats that are associated with springs and seeps that support lush vegetation that stock prefer as primary forage (pers. obs., Milkranch and Gardner meadows within the Highland
Lakes Grazing Allotment).
The need for protection of all habitats utilized by B. canorus presents something of a problem for management as the protection of breeding pools and meadows alone increases the grazing pressure on the, thus far, unprotected upland habitats, which may have a greater long-term impact on local population viability than the annual cohort losses that breeding pool exclosures are intended to prevent
(for similar arguments regarding other amphibian species see, Dodd 1996; Denton &
Beebee 1997; Dodd & Cade 1998; Semlitsch 1998, 2000, 2002; Semlitsch 2003b;
Semlitsch & Bodie 2003; Schabetsberger et al. 2004; Trenham & Shaffer 2005).
160
Bufo canorus are documented to reach 18+ years of age (Morton 1982; Kagarise
Sherman & Morton 1984), and several adult B. canorus PIT tagged during this study were recaptured by Forest Service personnel in 2006 and 2007 (Brown, pers. com.), which makes these individuals at least 10 years of age. The loss of adult toads from such a long-lived species can have a greater impact on long-term local population recruitment than the loss of even a large percentage of the annual juvenile cohort.
However, repeated cohort losses due to grazing impacts and/or breeding pool desiccation caused by the lowering of the meadow water table due to stream channel erosion can eventually lead to local population extinction (e.g., meadow 2.7 mi south
Hwy 4 on Highland Lakes road, pers. obs.). The balancing act between protecting breeding pools and protecting upland habitat will require a good deal more data on the survivorship of B. canorus life stages and the impacts that grazing (both current and historical) have on core habitat than is currently available before firm conclusions can be drawn regarding where and how much grazing, if any, local B. canorus populations can tolerate without population viability being lost. Given this high level of uncertainty regarding the long-term impacts of grazing on B. canorus and its habitat and given its functional Threatened Species status, the prudent course of action is to protect the meadow habitat utilized for breeding and juvenile rearing, the upland foraging habitat utilized by subadult and adult toads, as well as the overwintering habitats and migration corridors between these habitat types from all grazing impacts.
Functionally the core B. canorus habitat in need of protection is comprised of a series of approximately concentric circles of increasing distances from a given point
161
that contain the various habitat types utilized by this toad. The breeding pool habitat
type, or wetland, is the center circle (~50 m), which is surrounded by the meadow
habitat type belt (<100-150 m), followed by a band containing the overwintering
burrows (~150-200 m) and finally the band containing the upland habitats (~150-660
m) that are typically located farther from the breeding pools than any of the other
habitat types. If the 95% confidence interval of dispersal distance for the entire
population, which was found to be 83.99 meters (Table 11; see also, Figure 32) for
this study, was used to define the core habitat, none of the upland adult foraging
habitat would be included in the area in need of protection. Further, the migration
corridors from breeding habitat to foraging habitat and from foraging habitat to
overwintering habitat, which would be difficult-to-impossible to characterize given
our current state of knowledge regarding the ecology of B. canorus, would not be
protected by the 84 meter diameter circle. Thus, utilizing the 95% confidence
interval of adult male toads located in upland habitat, which was found to be 444.76
meters during this study, as the radius of a core habitat circle would better protect
breeding habitat, rearing habitat, the intermediate overwintering habitat, and a
significant portion of the upland habitat as well as the migration corridors between
these habitat types. However, a 450 meter radius will not protect the entire upland
habitat utilized by adult B. canorus during this study, nor will it protect all of the overwintering and foraging habitats previously reported (Kagarise Sherman 1980;
Morton 1981). Thus the 450 meter B. canorus core habitat estimate obtained from this study should be considered the bare minimum area in need of protection as this study found several adult male toads ranging up to 657 meters from the breeding
162
pools, and Morton (1981) found several adult female toads 750 meters from the nearest breeding pool; so the core habitat estimate may need to be increased as more research is conducted on the movements of adult B. canorus. Further, the sharing of a particular burrow by adult toads from two different local breeding populations, as was found during this study, suggests that migrations between local breeding populations could be easily accomplished by adult B. canorus between breeding seasons if individual toads were so inclined. Thus, a core habitat radius of 450 meters would not only fail to incorporate all of the habitat utilized by adult male B. canorus during this and other studies (see, Morton 1981), it would also fail to protect metapopulation dynamics and other landscape-level population processes that are necessary for continued species viability (see, Brown & Kodric-Brown 1977; Gill
1978; Pulliam 1988; Hanski & Gilpin 1991; Packard et al. 1992; Semlitsch 1998,
2000, 2002; Semlitsch 2003a; Semlitsch & Bodie 2003).
Finally, this core habitat estimate should be enclosed within a 50 meter terrestrial habitat buffer zone to reduce edge effects of forest management activities on the core habitat of this species (deMaynadier & Hunter 1995; Murcia 1995;
Semlitsch 1998; Semlitsch 2003a, b; Semlitsch & Bodie 2003), thereby providing a minimum core habitat protection zone radius of 500 meters from the center of the actively used breeding pools for local B. canorus breeding populations (Figure 35).
As the diameter of the core habitat increases from meadows only to including overwintering and upland foraging habitats, the amount of unsuitable forest and dry- rocky habitat included in the core habitat estimate also increases (see, Schabetsberger et al. 2004). However, in the case of B. canorus the primary agent of manageable
163
impact is livestock grazing and there is very little suitable forage for stock in forest or dry-rocky habitats (Kie & Boroski 1996), so the inclusion of these habitat areas, which are largely unused by B. canorus, will have little effect on management issues relating to consumptive use on National Forest lands. However, functionally, the 500 meter core habitat estimate virtually eliminates the primary forage available for stock grazing in the high elevation Sierra Nevada.
164
LITERATURE CITED
Albright, R., L. Hanson, P. Kaunert, C. Madden, A. Palmer, R. Ruediger, D. Van
Keuren, R. Wetzel, L. Conway, and J. Frazier. 1994. Highland Lakes Term
Permit and Allotment Management Plan. Pages 1-76. Stanislaus National
Forest, Sonora, CA.
Armour, C. L., D. A. Duff, and W. Elmore. 1991. The effects of livestock grazing on
riparian and stream ecosystems. Fisheries 16:7-11.
Armour, C. L., D. A. Duff, and W. Elmore. 1994. The effects of livestock grazing on
western riparian and stream ecosystems. Fisheries 19:9-12.
Bartelt, P. E. 1994 [abstract]. A plastic belt for attaching radio transmitters to
anurans. Joint Annual Meeting of the Herpetologists' League and the Society
for the Study of Amphibians and Reptiles, University of Georga, Athens,
Georiga.
Bartelt, P. E., and C. R. Peterson. 2000. A description and evaluation of a plastic belt
for attaching radio transmitters to western toads (Bufo boreas). Northwestern
Naturalist 81:122-128.
Bartelt, P. E., C. R. Peterson, and R. W. Klaverb. 2004. Sexual differences in the
post-breeding movements and habitats selected by western toads (Bufo
boreas) in southeastern Idaho. Herpetologica 60:455-467.
Beebee, T. J. C. 1996. Ecology and Conservation of Amphibians. Chapman & Hall,
London.
165
Belsky, A. J., A. Matzke, and S. Uselman. 1999. Survey of livestock influences on
stream and riparian ecosystems in the western United States. Journal of Soil
and Water Conservation 54:419-431.
Biek, R., W. C. Funk, B. A. Maxell, and L. S. Mills. 2002. What is missing in
amphibian decline research: Insights from ecological sensitivity analysis.
Conservation Biology 16:728-734.
Blair, W. F. 1953. Growth, dispersal and age at sexual maturity of the Mexican toad
(Bufo valliceps Wiegmann). Copeia 1953:208-212.
Blaustein, A. R., and D. B. Wake. 1990. Declining amphibian populations: A global
phenomenon? Trends in Ecology & Evolution 5:203-204.
Bohn, C. C., and J. C. Buckhouse. 1985. Some response of riparian soils to grazing
management in northeastern Oregon. Journal of Range Management 38:378-
381.
Bosman, W., J. J. van Gelder, and H. Strijbosch. 1996. Hibernation sites of the toads
Bufo bufo and Bufo calmita in a river floodplain. Herpetological Journal 6:83-
86.
Bradford, D. F. 1991. Mass mortality and extinction in a high-elevation population of
Rana muscosa. Journal of Herpetology 25:174-177.
Bradford, D. F., and M. S. Gordon. 1992. Aquatic Amphibians in the Sierra Nevada:
Current Status and Potential Effects of Acidic Deposition on Populations.
California Air Resources Board, Contract No. A932-139., Sacramento, CA.
Contract No. A932-139.
166
Bradford, D. F., D. M. Graber, and F. Tabatabai. 1994. Population declines on the
native frog, Rana muscosa, in Sequoia and Kings Canyon National Parks,
California. Southwestern Naturalist 39:323-327.
Bradford, D. F., F. Tabatabai, and D. M. Graber. 1993. Isolation of remaining
populations of the native frog, Rana muscosa, by introduced fishes in Sequoia
and Kings Canyon National Parks, California. Conservation Biology 7:882-
888.
Breckenridge, W. J., and J. R. Tester. 1961. Growth, local movements and
hibernation of the Manitoba toad, Bufo hemiophrys. Ecology 42:637-646.
Brown, C. 2002. Population and Habitat Monitoring for the Yosemite Toad: Sierra
Nevada Framework Project. Pages 1-29 +Attachments. USFS, Sacramento,
CA.
Brown, J. H., and A. Kodric-Brown. 1977. Turnover rates in insular biography: effect
of immigration on extinction. Ecology 58:445-449.
Calhoun, A. J. K., and J. Hunter, Malcolm L. 2003. Managing ecosystems for
amphibian conservation. Pp. 228-241. In R. D. Semlitsch (Ed.). Amphibian
Conservation. Smithsonian Books, Washington, D.C.
Camp, C. L. 1916. Description of Bufo canorus, a new toad from the Yosemite
National Park. University of California Publications in Zoology 17:11-14.
Campbell, J. B. 1970. Hibernacula of a population of Bufo boreas in the Colorado
front range. Herpetologica 26:278-282.
Campbell, G. S., and J. M. Norman 1998. An Introduction to Environmental
Biophysics. Springer, New York, NY.
167
Camper, J. D., and J. R. Dixon. 1988. Evaluation of a microchip marking system for
amphibians and reptiles. Pages 1-22. Texas Parks and Wildlife Department.
Carpenter, C. C. 1954. A study of amphibian movement in the Jackson Hole Wildlife
Park. Copeia 1954:197-200.
Cunningham, J. D. 1963. Additional observations on the ecology of the Yosemite
toad, Bufo canorus. Herpetologica 19:56-61. deMaynadier, P. G., and J. Hunter, Malcolm L. 1995. The relationship between forest
management and amphibian ecology: A review of the North American
literature. Environmental Reviews 3:230-261.
Denton, J. S., and T. J. C. Beebee. 1997. Effects of predator interactions, prey
palatability and habitat structure on survival of natterjack toad Bufo calamita
larvae in replicated semi-natural ponds. Ecography 20:166-174.
Denton, J. S., S. P. Hitchings, T. J. C. Beebee, and A. Gent. 1997. A recovery
program for the natterjack toad (Bufo calamita) in Britain. Conservation
Biology 11:1329-1338.
Derlet, R. W., and J. R. Carlson. 2006. Coli form bacteria in Sierra Nevada
wilderness lakes and streams: What is the impact of backpackers, pack
animals, and cattle? Wilderness and Environmental Medicine 17:15-20.
Dodd, C. K., and B. S. Cade. 1998. Movement patterns and the conservation of
amphibians breeding in small, temporary wetlands. Conservation Biology
12:331-339.
Dodd, C. K., Jr. 1996. Use of terrestrial habitats by amphibians in the sandhill
uplands of north-ventral Florida. Alytes 14:1-52.
168
Dole, J. W. 1965. Summer movements of adult leopard frogs, Rana pipiens Schreber,
in northern Michigan. Ecology 46:236-255.
Donnelly, M. A., C. Guyer, J. E. Juterbock, and R. A. Alford. 1994. Techniques for
marking amphibians. Pp. 277-284. In W. R. Heyer, M. A. Donnelly, R. W.
McDiarmid, L.-A. C. Hayek, and M. S. Foster (Eds.). Measuring and
Monitoring Biological Diversity: Standard Methods for Amphibians.
Smithsonian Institution Press, Washington, D.C.
Drost, C. A., and G. M. Fellers. 1996. Collapse of a regional frog fauna in the
Yosemite area of the California Sierra Nevada, USA. Conservation Biology
10:414-425.
Dubois, A. 1991. Les amphibiens des régions tropicales: fracteurs de décline et
d'extinction. Cahiers d'Outre-Mer 42:393-398.
Dudley, T. L., and W. E. Dietrich. 1995. Effects of cattle grazing exclosures on the
recovery of riparian ecosystems in the southern Sierra Nevada. Wildland
Resources Center, University of California, Davis, CA.
Eggert, C., P.-H. Peyret, and R. Guyetant. 1999. Two complementary methods for
studying amphibian terrestrial movements. Current Studies in Herpetology
1999:95-97.
Erman, N. 1996. Status of aquatic invertebrates. Pp. 987-1008. In Sierra Nevada
Ecosystem Project: Final Report to Congress. University of California,
Centers for Water and Wildland Resources, Davis, CA.
Erman, N. A. 2002. Lessons from a long-term study of springs and spring
invertebrates (Sierra Nevada, California, USA) and implications for
169
conservation and management. Pp. 1-13. In Conference Proceedings: Spring-
fed wetlands -- Important scientific and cultural resources of the
Intermountain Region.
Ewert, M. A. 1969. Seasonal movements of the toads Bufo americanus and B.
cognatus in northwestern Minnesota. Pp. 1-193. Ph.D. dissertation.
Department of Biology. University of Minnesota, Minnesota.
Fasola, M., F. Barbieri, and L. Canova. 1993. Test of an electronic individual tag for
newts. Herpetological Journal 3:149-150.
Fitch, H. S. 1958. Home ranges, territories, and seasonal movements of vertebrates of
the Natural History Reserve. University of Kansas Publications of the
Museum of Natural History 11:63-326.
Fleischner, T. L. 1994. Ecological costs of livestock grazing in Western North
America. Conservation Biology 8:629-644.
Flenniken, M., R. R. McEldowney, W. C. Leininger, G. W. Frasier, and M. J. Trlica.
2001. Hydrologic responses of a montane riparian ecosystem following cattle
use. Journal of Range Management 54:567-574.
Gibbons, J. W., and K. M. Andrews. 2004. PIT tagging: simple technology at its best.
Bioscience 54:477-458.
Gill, D. E. 1978. The metapopulation ecology of the red-spotted newt, Notophthalmus
viridescens (Ralimesque). Ecological Monographs 48:145-166.
Grinnell, J., and C. L. Camp. 1917. A distributional list of the amphibians and reptiles
of California. University of California Publications in Zoology 17:127-208.
170
Grinnell, J., and T. I. Storer 1924. Animal Life in the Yosemite. University of
California Press, Berkeley, California.
Grubb, J. C. 1970. Orientation in post-reproductive Mexican toads, Bufo valliceps.
Copeia 1970:674-680.
Hanski, I., and M. Gilpin. 1991. Metapopulation dynamics: Brief-history and
conceptual domain. Biological Journal of the Linnean Society 42:3-16.
Herbst, D. B., and R. L. Knapp. 1995. Biomonitoring of rangeland streams under
differing livestock grazing practices. Bulletin of the North American
Benthological Society 14:176.
Heusser, H. 1967. Wanderungen und Sommerquartiere der Erdkröte (Bufo Bufo L.).
Ph.D. dissertation. Department of Biology. University of Zürich, Switzerland.
Heyer, W. R. 1994. Thread bobbins. Pages 153-155. In W. R. Heyer, M. A. Donnelly,
R. W. McDiarmid, L.-A. C. Hayek, and M. S. Foster (Eds.). Measuring and
Monitoring Biological Diversity: Standard Methods for Amphibians.
Smithsonian Institution Press, Washington, D.C.
Heyer, W. R., M. A. Donnelly, R. W. McDiarmid, L.-A. C. Hayek, and M. S. Foster
(Eds.). 1994. Measuring and Monitoring Biological Diversity: Standard
Methods for Amphibians. Smithsonian Intuition Press, Washington D.C.
Holenweg, A. K., and H. U. Reyer. 2000. Hibernation behavior of Rana lessonae and
R. esculenta in their natural habitat. Oecologia 123:41-47.
Houlahan, J. E., C. S. Findlay, A. H. Meyer, S. L. Kuzmin, and B. R. Schmidt. 2001.
Global amphibian population declines. Nature 412:499-500.
171
Houlahan, J. E., C. S. Findlay, B. R. Schmidt, A. H. Meyer, and S. L. Kuzmin. 2000.
Quantitative evidence for global amphibian population declines. Nature
404:752-755.
Jennings, M. R. 1996. Status of Amphibians. Pages 921-944. In Sierra Nevada
Ecosystem Project: Final Report to Congress. University of California,
Centers for Water and Wildland Resources, Davis, CA.
Jennings, M. R., and M. P. Hayes. 1994. Amphibian and Reptile Species of Special
Concern in California. Pages iv-255. California Department of Fish & Game,
Inland Fisheries Division, Rancho Cordova, CA.
Jepson, W. L. 1975. A Manual of the Flowering Plants of California. University of
California Press, Berkeley, CA.
Kagarise Sherman, C. 1980. A Comparison of the Natural History and Mating System
of two Anurans: Yosemite Toads (Bufo canorus) and Black Toads (Bufo
exsul). Ph.D. dissertation. University of Michigan, Ann Arbor.
Kagarise Sherman, C., and M. L. Morton. 1984. The toad that stays on its toes.
Natural History 93:72-78.
Kagarise Sherman, C., and M. L. Morton. 1993. Population declines of Yosemite
toads in the eastern Sierra Nevada of California. Journal of Herpetology
27:186-198.
Karlstrom, E. L. 1957. The use of Co60 as a tag for recovering amphibians in the field.
Ecology 38:187-195.
Karlstrom, E. L. 1962. The toad genus Bufo in the Sierra Nevada of California.
University of California Publications in Zoology 62:1-104.
172
Karlstrom, E. L., and R. L. Livezey. 1955. The eggs and larvae of the Yosemite toad
(Bufo canorus, Camp). Herpetologica 11:221-227.
Kattelmann, R., and M. Embury. 1996. Riparian areas and wetlands. Pages 201-269.
In Sierra Nevada Ecosystem Project: Final Report to Congress. U.C., Davis,
Centers for Water and Wildlife Resources, Davis, CA.
Kauffman, J. B., and W. C. Krueger. 1984. Livestock impacts on riparian ecosystems
and streamside management implications: A review. Journal of Range
Management 37:430-438.
Kauffman, J. B., W. C. Krueger, and M. Vavra. 1983. Effects of late season cattle
grazing on riparian plant communities. Journal of Range Management 36:685-
691.
Kie, J. G., and B. B. Boroski. 1996. Cattle distribution, habitats, and diets in the
Sierra Nevada of California. Journal of Range Management 49:482-488.
Kusano, T., K. Maruyama, and S. Kaneko. 1995. Post-breeding dispersal of the
Japanese toad, Bufo japonicus formosus. Journal of Herpetology 29:633-638.
Lamoureux, V. S., and D. M. Madison. 1999. Overwintering habitats of radio-
implanted green frogs, Rana clamitans. Journal of Herpetology 33:430-435.
Lemckert, F., and T. Brassil. 2000. Movements and habitat use of the endangered
giant barred river frog (Mixophyes iteratus) and the implications for its
conservation in timber production forests. Biological Conservation 96:177-
184.
Lind, A. J., R. Grasso, S. Parks, P. A. Stine, B. Allen-Diaz, S. McIlroy, K. Tate, L.
Roche, W. FROST, and N. K. McDougald. 2006 [abstract]. Determining the
173
Effects of Livestock Grazing on Yosemite Toads (Bufo canorus) and their
Habitat: An Adaptive Management Study. Declining Amphibian Task Force
(DAPTF) California-Nevada Working Group Meeting 2006, Humboldt State
University, Arcata, CA.
Madison, D. M. 1997. The emigration of radio-implanted spotted salamanders,
Ambystoma maculatum. Journal of Herpetology 31:542-551.
Martin, D., and H. Hong. 1991. The use of Bactine in the treatment of open wounds
and other lesions in captive anurans. Herpetological Review 22:21.
Martin, D. L. 1990a [abstract]. Food habits of the Yosemite toad (Bufo canorus).
Page 73. Joint Annual Meeting: The 38th Annual Meeting of The
Herpetologists' League and The 33rd Annual Meeting of The Society for the
Study of Amphibians and Reptiles, Tulane University, New Orleans,
Louisiana.
Martin, D. L. 1990b [abstract]. Population status of the Yosemite toad (Bufo
canorus): An interim report. Page 74. Joint Annual Meeting of the
Herpetologists' League and the Society for the Study of Amphibians and
Reptiles, Tulane University, New Orleans, Louisiana.
Martin, D. L. 1991a [abstract]. Population census of a species of special concern: The
Yosemite toad (Bufo canorus). Page 31. Fourth Biennial Conference of
Research in California's National Parks. Cooperative National Parks
Resources Studies Unit, University of California, Davis, California.
Martin, D. L. 1991b [abstract]. The dramatic decline of a species of special concern:
The Yosemite Toad (Bufo canorus). Page 78. Joint Annual Meeting of the
174
Herpetologists' League and the Society for the Study of Amphibians and
Reptiles, Penn State University, University Park, Pennsylvania.
Martin, D. L. 1991c. Captive husbandry as a technique to conserve a species of
special concern, the Yosemite toad. Pages 16-32. In R. E. Staub (Ed.). Fifth
Conference on the Captive Propagation and Husbandry of Reptiles and
Amphibians. Northern California Herpetological Society, University of
California, Davis, CA.
Martin, D. L. 1994 [abstract]. Standardized survey of anurans in the Sierra Nevada.
Page 166. Second World Congress of Herpetology, University of Adelaide,
South Australia.
Martin, D. L., W. E. Bros, D. L. Dondero, M. R. Jennings, and H. H. Welsh. 1993.
Sierra Nevada Anuran Survey: An Investigation of Amphibian population
abundance in The National Forests of The Sierra Nevada of California.
Canorus Ltd. Press, Sacramento, CA.
Martin, D. L., M. R. Jennings, H. H. Welsh, and D. Dondero 1992. Anuran Survey
Protocol for the Sierra Nevada of California. Canorus Ltd. Press, Sacramento,
CA.
McComb, W. C., C. L. Chambers, and M. Newton. 1993. Small Mammal and
Amphibian Communities and Habitat Associations in Red Alder Stands,
Central Oregon Coast Range. Northwest Science 67:181-188.
Meehan, W. R., and W. S. Platts. 1978. Livestock grazing and the aquatic
environment. Journal of Soil and Water Conservation 33:274-278.
175
Menke, J. W., C. Davis, and P. Beesley. 1996. Rangeland Assessment. Pages 901-
972. In Sierra Nevada Ecosystem Project: Final Report to Congress.
University of California, Centers for Water and Wildland Resources, Davis,
CA.
Miaud, C., D. Sanuy, and J.-N. Avrillier. 2000. Terrestrial movements of the
natterjack toad Bufo calamita (Amphibia, Anura) in a semi-arid, agricultural
landscape. Amphibia-Reptilia 21:357-369.
Mohr, C. O. 1947. Table of equivalent populations of North American small
mammals. American Midland Naturalist 37:223-249.
Morton, M. L. 1981. Seasonal changes in total body lipid and liver weight in the
Yosemite toad. Copeia 1981:234-238.
Morton, M. L. 1982. Natural history of the Yosemite toad. National Geographic
Society Research Reports 14:499-503.
Mullally, D. P., Pvt. 1953. Observations on the ecology of the toad Bufo canorus.
Copeia 1953:182-183.
Mullally, D. P., Pvt., and J. D. Cunningham. 1956. Aspects of the thermal ecology of
the Yosemite toad. Herpetologica 12:57-67.
Murcia, C. 1995. Edge effects in fragmented forests: implications for conservation.
Trends in Ecology & Evolution 10:58-62.
Muths, E. 2003. Home range and movements of boreal toads in undisturbed habitat.
Copeia:160-165.
Odion, D. C., T. L. Dudley, and C. M. D'Antonio. 1990. Cattle grazing in
southeastern Sierra meadows: Ecosystem change and prospects for recovery.
176
Pages 277-292. In C. A. Hall, and V. Doyle-Jones (Eds.). Plant Biology of
Eastern California. White Mountain Research Station, University of
California, Los Angeles, CA.
Oldham, R. S. 1966. Spring movements in the American toad, Bufo americanus.
Canadian Journal of Zoology 44:63-100.
Packard, S. J., H. R. Pulliam, J. Dunning, B. John, and J. Liu. 1992. Population
Dynamics in Complex Landscapes: A Case Study. Ecological Applications
2:165-177.
Pilliod, D. S., C. R. Peterson, and P. I. Ritson. 2002. Seasonal migration of Columbia
spotted frogs (Rana luteiventris) among complementary resources in a high
mountain basin. Canadian Journal of Zoology-Revue Canadienne De Zoologie
80:1849-1862.
Platts, W. S. 1991. Livestock grazing. In W. R. Meehan (Ed.). Influences of Forest
and Rangeland Management on Salmonid Fishes and their Habitats. American
Fisheries Society, Bethesda, MD.
Powell, R. A. 2000. Animal home ranges and territories and home range estimators.
Pages 65-110. In L. Boitani, and T. K. Fuller (Eds.). Research Techniques in
Animal Ecology: Controversies and Consequences. Columbia University
Press, New York, NY.
Pulliam, H. R. 1988. Sources, sinks, and population regulation. American Naturalist
132:652-661.
177
Quinn, J., and J. Kissack. 1994. Tissue adhesives for laceration repair during sporting
events. Clinical Journal of Sport Medicine 4:245-248.
Rathbun, G. B., and T. G. Murphey. 1996. Evaluation of a radio-belt for ranid frogs.
Herpetological Review 27:187-189.
Ratliff, R. D. 1982. A Meadow Site Classification for the Sierra Nevada, California.
Pp. 1-16. GTR-PSW-60. Pacific Southwest Research Station, Forest Service,
U.S. Dept. of Agriculture, Berkeley, CA.
Ratliff, R. D. 1985. Meadows in the Sierra Nevada of California: State of knowledge.
Pp. 1-52. GTR-PSW-84. Pacific Southwest Forest and Range Experiment
Station, Forest Service, U.S. Dept. of Agriculture, Berkeley.
Richards, S. J., U. Sinsch, and R. A. Alford. 1994. Radio-tracking. Pp. 155-158. In
W. R. Heyer, M. A. Donnelly, R. W. McDiarmid, L.-A. C. Hayek, and M. S.
Foster (Eds.). Measuring and Monitoring Biological Diversity: Standard
Methods for Amphibians. Smithsonian Institution Press, Washington, D.C.
Richter, S. C., J. E. Young, R. A. Seigel, and G. N. Johnson. 2001. Postbreeding
movements of the dark gopher frog, Rana sevosa Goin and Netting:
Implications for conservation and management. Journal of Herpetology
35:316-321.
Rudolph, D. C., and J. G. Dickson. 1990. Streamside zone width and amphibian and
reptile abundance. Southwestern Naturalist 35:472-476.
Schabetsberger, R., R. Jehle, A. Maletzky, J. Pesta, and M. Sztatecsny. 2004.
Delineation of terrestrial reserves for amphibians: post-breeding migrations of
178
Italian crested newts (Triturus c. carnifex) at high altitude. Biological
Conservation 117:95-104.
Schwarzkopf, L., and R. A. Alford. 1996. Desiccation and shelter-site use in a
tropical amphibian: comparing toads with physical models. Functional
Ecology 10:193-200.
Seebacher, F., and R. A. Alford. 1999. Movement and microhabitat use of a terrestrial
amphibian (Bufo marinus) on a tropical island: Seasonal variation and
environmental correlates. Journal of Herpetology 33:208-214.
Semlitsch, R. D. 1998. Biological delineation of terrestrial buffer zones for pond-
breeding salamanders. Conservation Biology 12:1113-1119.
Semlitsch, R. D. 2000. Principles for management of aquatic-breeding amphibians.
Journal of Wildlife Management 64:615-631.
Semlitsch, R. D. 2002. Critical elements for biologically based recovery plans of
aquatic-breeding amphibians. Conservation Biology 16:619-629.
Semlitsch, R. D. (Ed.) 2003a. Amphibian Conservation. Smithsonian Books,
Washington, D.C.
Semlitsch, R. D. 2003b. Conservation of pond-breeding amphibians. Pp. 8-23. In R.
D. Semlitsch (Ed.). Amphibian Conservation. Smithsonian Books,
Washington, D. C.
Semlitsch, R. D., and J. R. Bodie. 2003. Biological criteria for buffer zones around
wetlands and riparian habitats for amphibians and reptiles. Conservation
Biology 17:1219-1228.
179
Semlitsch, R. D., and B. B. Rothermel. 2003. A foundation for conservation and
management of amphibians. Pp. 242-259. In R. D. Semlitsch (Ed.).
Amphibian Conservation. Smithsonian Books, Washington, D.C.
Sinsch, U. 1988a. Seasonal-Changes in the Migratory Behavior of the Toad Bufo
bufo: Direction and Magnitude of Movements. Oecologia 76:390-398.
Sinsch, U. 1988b. Temporal spacing of breeding activity in the natterjack toad, Bufo
calamita. Oecologia 76:399-407.
Sinsch, U. 1990. Migration and orientation in anuran amphibians. Ethology Ecology
& Evolution 2:65-79.
Sinsch, U. 1991. The orientation behavior of amphibians. Herpetological Journal
1:541-544.
Sinsch, U. 1992a. Sex-biased site fidelity and orientation behavior in reproductive
natterjack toads (Bufo calamita). Ethology Ecology & Evolution 4:15-32.
Sinsch, U. 1992b. Structure and dynamic of a natterjack toad metapopulation (Bufo
calamita). Oecologia 90:489-499.
Sinsch, U. 1992c. Zwei nene markierungamethoden zur individuellen identifikation
von amphibian in langfristigen freilanduntersuchungen: Erste erfahrungen bei
kreuzkroten. Salamandra 28:116-128.
Sinsch, U. 1997. Postmetamorphic dispersal and recruitment of first breeders in a
Bufo calamita metapopulation. Oecologia 112:42-47.
Stebbins, R. C. 1951. Amphibians of Western North America. University of
California Press, Berkeley, California.
180
Stebbins, R. C. 1954. Amphibians and Reptiles of Western North America. McGraw-
Hill Book Company, Inc., New York, NY.
Stebbins, R. C. 1966. A Field Guide to Western Reptiles and Amphibians. Houghton
Mifflin Company, Boston, Mass.
Stebbins, R. C. 1985. A Field Guide to Western Reptiles and Amphibians. Houghton
Mifflin Co., Boston, Mass.
Stebbins, R. C., and N. W. Cohen 1995. A Natural History of Amphibians. Princeton
University Press, Princeton, NJ.
Stephenson, G. R., and L. V. Street. 1978. Bacterial variations in streams from a
southwest Idaho rangeland watershed. Journal of Environmental Quality
7:150-157.
Storer, T. I. 1925. A synopsis of the amphibia of California. University of California
Publications in Zoology 27:1-307.
Storer, T. I., and R. L. Usinger 1963. Sierra Nevada Natural History: An Illustrated
Handbook. University of California Press, Berkeley, CA.
Stuart, S. N., J. S. Chanson, N. A. Cox, B. E. Young, A. S. L. Rodrigues, D. L.
Fischman, and R. W. Waller. 2004. Status and trends of amphibian declines
and extinctions worldwide. Science 306:1783-1786.
Sweet, S. S. 1993. Second Report on the Biology and Status of the Arroyo Toad
(Bufo microscaphus californicus) on the Los Padres National Forest of
Southern California. Pp. ii-73. Department of Biological Sciences, University
of California, Santa Barbara, CA.
181
Sztatecsny, M., and R. Schabetsberger. 2005. In to thin air: Vertical migration, body
condition, and quality of terrestrial habitats of alpine common toads, Bufo
Bufo. Canadian Journal of Zoology-Revue Canadienne De Zoologie 83:788-
796.
Tenpas, R. J., and D. B. Glazer. 2007 [legal document]. High Sierra Hikers Assoc., et
al. v. Bernie Weingardt, et al. C-00-1239-EDL. Federal Defendants’
Memorandum of Law re: Cross-Motions for Summary Judgment. United
States District Court, Northern District of California, San Francisco Division.
Tracy, C. R. 1976. A model of the dynamic exchanges of water and energy between a
terrestrial amphibian and its environment. Ecological Monographs 46:293-
326.
Tramontano, R. 1997. Continuous radio-tracking of the common frog, Rana
temporaria. Pp 359-365. In W. Bohme, W. Bischoff, and T. Ziegler (Eds.).
Herpetologia Bonnensis, 1997:359-365.
Trenham, P. C., and H. B. Shaffer. 2005. Amphibian upland habitat use and its
consequences for population viability. Ecological Applications 15:1158-1168.
Trimble, S. W., and A. C. Mendel. 1995. The cow as a geomorphic agent: a critical-
review. Geomorphology 13:233-253.
USDA. 2004. Sierra Nevada Forest Plan Amendment Final Supplemental
Environmental Impact Statement. Forest Service, Pacific Southwest Region,
Vallejo, CA. January 2004. van Nuland, G. J., and P. F. H. Claus. 1981. The development of a radio tracking
system for anuran species. Amphibia-Reptilia 2:107-116.
182
Vonesh, J. R., and O. De la Cruz. 2002. Complex life cycles and density dependence:
assessing the contribution of egg mortality to amphibian declines. Oecologia
133:325-333.
Wake, D. B., and H. J. Morowitz. 1990. Declining amphibian populations: A global
phenomenon? Pp. 1-11. National Research Council Board on Biology, Irvine,
CA.
Waye, H. L. 2001. Teflon tubing as radio transmitter belt material for northern
leopard frogs (Rana pipiens). Herpetological Review 32:88-89.
Weissberg, D., and R. H. Goetz. 1964. Tissue reactions to methyl-2-cyanoacrylate
(Eastman 910 monomer). Surgical Forum 15:226-227.
White, G. C., and R. A. Garrott 1990. Analysis of Wildlife Radio-Tracking Data.
Academic Press, San Diego, CA.
Wilbur, H. M. 1980. Complex life cycles. Annual Review of Ecology and
Systematics 11:67-93.
Wilson, D. S. 1994. Tracking small animals with thread bobbins. Herpetological
Review 25:13-14.
Wold, J. L. 1995. Decision Notice and Finding of No Significant Impact for the
Highland Lakes Term Permit and Allotment Management Plan. Pp. 1-8.
Stanislaus National Forest, Sonora, CA.
Wood, T. S. 1977 [unpublished manuscript]. Food Habits of Bufo canorus.
Department of Biological Sciences. Occidental College, Los Angeles, CA.
Wright, A. A., and A. H. Wright 1933. Handbook of Frogs and Toads of the United
States and Canada. The Comstock Publishing Co., Inc., Ithaca, New York.
183
Wright, A. H., and A. A. Wright 1949. Handbook of Frogs and Toads of the United
States and Canada. Comstock Publishing Co., Inc., Ithaca, New York.
Zar, J. H. 1984. Biostatistical Analysis. Prentice-Hall Inc., Englewood Clifts, N.J.
Zug, G. R., and P. B. Zug 1979. The marine toad, Bufo marinus: a natural history
resume of native populations. Contributions in zoology 284. Smithsonian
Institution, Washington, D.C.
184
TABLES Capture Meadow Total Range † Max Max Distance Avg. Avg. Dist./Day Dist. Total No. No. Fi xes Days Total tracked with radio transmitters. with radio tracked B. canorus B. SVL Start Date End Date Wt. Toad Toad Movement data summary for for summary data Movement PIT TagPIT Sex 000132F3C3 F 31.2 67 27-Sep-95 10-Dec-95 * 75 15 101.63 1.36 70.7 441.54 Pools Mid 000132C94A F 48.4000132A9C9 76 25-Aug-95 17-Sep-95 M 23 28.2 7 64 16-Aug-95 100.4 10-Dec-95 * 4.37 116 44 91.62 452.14 787.66 Mdw. Tryon 3.9 199.39 10,543.50 Mid Pool s 000132E8DA M 29.7 63 25-Aug-95 10-Dec-95 * 107 33 167.07 1.56 113.53 875.99 Pools Mid 0001333EBFT F 45 720001324E3CT00013246C0T M 24-Jul-97 12-Aug-97000133285CT M 19 20 M 20.5 25 62 22 58 17-Jun-97 77.5 17-Jun-97 17-Jul-97 27-Aug-97 64 17-Jun-97 3.88 70 31 26-Aug-97 49 17 71 31.21 1763.11 512.1 35 2,176.68 56.87 Pools North 892.03 7.32 194.41 12.56 11,290.14 Pools 214.13 North 637.06 9,373.55 33,869.75 Pools North Pools North 00013263BDT F000133C20AT 22 M 60 19.5 17-Jun-97 23-Aug-97 65 68 28-Jun-96 16-Jul-96 46 19 618.98 11 9.1 258.19 275.97 13.59 9,355.37 184.14 Pools North 5,865.11 Pools North Table 1. Maximum† strai ghtline distanceThese * were toads from actively trackedtracking 24 until October 1995. Afterthis date their position ori theirburrows in was only snow. covered ginin was the burrow to time 1995 farthest December which 10 by until periodically monitored position fix.
185
Capture Meadow Total Total Range † Max Max Distance Distance Avg. Avg. Dist./Day Total Distance Distance Traveled No. No. Fixes Days Total tracked with cocoon thread bobbins. thread cocoon with tracked B. canorus SVL Start Date Date End Wt. Toad Toad PIT TagPIT Sex O001326619 M 25.4 62 26-Sep-95 29-Sep-95 4 8 162.45 40.61 43.99 659.99 Mid Pools 000132A698T F 19.7 61.7 30-Jun-96 2-Jul-96 300013246C0T M000133285CT 6 M 20.5000133B300T 57.7 M00013284D2T 20 88.13 17-Jun-97 M 18-Jun-97 31 63.9 2 29.38 21 17-Jun-97 65.7 18-Jun-97 26-Jul-97 58.8 126.67 2 5 28-Jul-97 27-Jul-97 2,726.09 Pools North 28-Jul-97 3 4 96.27 2 6 158.13 48.14 4 156.84 79.07 16.22 27.39 52.28 135.35 47.11 1,319.36 Pools North Pools North 13.7 46.41 944.58 Pools North 7.48 35.07 Pools North 00013263BDT F000133C20AT 22 M 59.7 19.5000132AFC6T 17-Jun-97 64.6 19-Jun-97 28-Jun-96 M 3 1-Jul-96 20.4 4 9 60.8 30-Jun-96 126.25 9 1-Jul-96 42.08 237.74 2 59.44 67.12 1,296.90 Pools North 63.45 2 1,798.04 Pools North 109.29 54.65 73.42 658.86 Mid Pools 0001DB586AT M 19.8 58.2 28-Jun-96 1-Jul-96 4 7 123.65 30.91 53.46 425.49 North Pools 0001DA5A76T F 25.8 68.6 28-Jun-95 2-Jul-95 5 8 51.58 10.32 18.29 77.36 Mid Pools † Maximum straight line distance fromtracking originto farthest position fix. Table 2. Movement data summary for for summary data 2. Movement Table
186
Capture Meadow Radio Range Estimated Estimated Total Total Range Range String Radio Est. Dist. Dist. Est. String Total Dist. Dist. Total No. No. Fixes Days Total Total movement data collected by string-tracking and by radio-tracking by and string-tracking by collected data movement B. canorusB. SVL Start End Wt. Toad Toad PIT TagPIT Sex O001326619 M 25.37 62 26-Sep-95 29-Sep-95 4 8 162.45 82.66 659.99 231.52 Pools Mid 000132A698T F 19.73 61.7 30-Jun-96 2-Jul-96 3 6 164.55 145.24 2726.09 2304.48 Pools North 00013246C0T M000133285CT M000133B300T 20.5 M 57.700013284D2T 20 17-Jun-97 M 18-Jun-97 31 63.9 17-Jun-97 21 2 65.7 18-Jun-97 26-Jul-97 58.8 2 28-Jul-97 5 27-Jul-97 28-Jul-97 3 4 96.27 2 6 158.13 21.02 4 156.84 135.96 47.11 27.39 1319.36 94.67 43.03 3.44 14.28 944.58 Pools North Pools North 662.35 35.07 Pools North 17.06 Pools North 00013263BDT F 22 59.7 17-Jun-97 19-Jun-97 3 9 126.25 77.82 1296.9 666.98 Pools North 000133C20AT M000132AFC6T M 19.45 64.6 20.44 28-Jun-96 60.8 1-Jul-96 30-Jun-96 1-Jul-96 4 2 9 3 237.74 109.29 84.63 66.76 1798.04 1050.17 658.86 Pools North 16.67 Pools Mid 0001DA5A76T F 25.76 68.6 28-Jun-950001DB586AT 2-Jul-95 M 5 19.84 58.2 28-Jun-96 8 1-Jul-96 4 51.58 7 30.45 77.36 123.65 84.36 65.75 425.49 Pools Mid 200.86 Pools North techniques. Table 3. between Comparison
187
Distance Distance Traveled Range TypeRange Area seasonal activity seasonal activity periods. Package Tracking Days Total Total B. canorus canorus B. PIT Tag Sex Start Date End Date 000132F3C3 F 29-Sep-95 16-Oct-95 18 Radio Overwintering 41.09 71.1 O001326619 M 26-Sep-95 2-Oct-95 7 String Foraging 659.99 165.06 000132F3C3 F 27-Sep-95 29-Sep-95 3 Radio Foraging 74.24 30.53 000132A9C9 M 29-Sep-95 15-Oct-95 17 Radio Overwintering 69.23 141.33 000132C94A F 25-Aug-95 17-Sep-95 2 Radio Migration 102.39 74.75 000132A9C9 M 16-Aug-95 29-Sep-95 45 Radio Foraging 5252.95 310.81 000132E8DA M 26-Aug-95 16-Sep-95 19 Radio Overwintering 677.3 158.23 000132E8DA M 25-Aug-95 26-Aug-95 2 Radio Foraging 12.04 10.34 000133285CT M 17-Jun-97 19-Jun-97 3 String Migration 88.46 158.13 00013246C0T M 17-Jun-97 18-Jun-97 2 String Breeding 47.11 96.27 00013246C0T M000133285CT M 18-Jun-97 22-Jun-97 17-Jun-97 19-Jun-97 5 3 Radio Radio Migration Migration 671.75 9536.78 197.37 606.39 000133285CT M 19-Jun-97 26-Aug-97000133B300T 69 M 26-Jul-97 Radio 28-Jul-97 3 Foraging 1927.51 String 285.64 Foraging 944.58 156.84 00013246C0T M 4-Jul-97 27-Aug-97 54 Radio Foraging 6361.07 292.91 000133C20AT M000132A698T 30-Jun-96 1-Jul-96 F 2 30-Jun-96 2-Jul-96 Radio 3 Migration String 2016.11 Migration 189.08 2726.09 164.56 000133C20AT M 28-Jun-96 30-Jun-96 3 String Breeding 706.17 163.1 00013284D2T M 27-Jul-97 28-Jul-97 2 String Foraging 35.07 27.39 0001333EBFT F0001324E3CT 24-Jul-97 12-Aug-97 M 20 17-Jun-97 17-Jul-97 Radio 31 Radio Foraging 2176.68 Foraging 77.5 10883.23 314.59 00013263BDT F000132AFC6T 17-Jun-97 19-Jun-97 M 30-Jun-95 3 1-Jul-95 String 2 Migration String 1296.9 Migration 113.55 587.99 92.35 000132AFC6T M 30-Jun-95 1-Jul-95 2 String Breeding 7.06 16.94 00013263BDT F 17-Jun-97 23-Aug-97 68 Radio Foraging 5343.89 544.62 0001DB586AT M 28-Jun-96 29-Jun-96 2 String Breeding 425.49 123.65 0001DA5A76T F 28-Jun-95 2-Jul-95 5 String Foraging 77.36 51.58 Table 4. Range estimates for various various for estimates 4. Range Table
188
Table 5. Diel peroid movement distances for B. canorus by tracking method. Diel Tracking Distance PIT Tag Sex Date Period Method Traveled 000132C94A F 26-Aug-95 Durnal Radio 2.85 000132F3C3 F 27-Sep-95 Durnal Radio 13.10 000132F3C3 F 28-Sep-95 D urnal Radio 9.40 000132F3C3 F 29-Sep-95 D urnal Radio 0.00 00013263BDT F 19-Jun-97 D urnal Radio 2.49 00013263BDT F 4-Jul-97 Durnal Radio 22.97 00013263BDT F 16-Jul-97 D urnal Radio 0.00 00013263BDT F 17-Jul-97 D urnal Radio 0.00 00013263BDT F 23-Jul-97 D urnal Radio 14.25 00013263BDT F 24-Jul-97 D urnal Radio 9.49 0001333EBFT F 24-Jul-97 D urnal Radio 7.90 00013263BDT F 25-Jul-97 D urnal Radio 30.35 0001333EBFT F 25-Jul-97 D urnal Radio 0.00 00013263BDT F 26-Jul-97 D urnal Radio 0.00 0001333EBFT F 26-Jul-97 D urnal Radio 5.60 00013263BDT F 27-Jul-97 D urnal Radio 2.97 0001333EBFT F 27-Jul-97 D urnal Radio 6.27 00013263BDT F 28-Jul-97 D urnal Radio 57.40 0001333EBFT F 28-Jul-97 D urnal Radio 0.00 000132A9C9 M 17-Aug-95 Durnal Radio 19.15 000132A9C9 M 24-Aug-95 Durnal Radio 78.82 000132A9C9 M 25-Aug-95 Durnal Radio 6.12 000132E8DA M 25-Aug-95 Durnal Radio 0.00 000132A9C9 M 26-Aug-95 Durnal Radio 21.80 000132E8DA M 26-Aug-95 Durnal Radio 3.20 000132E8DA M 16-Sep-95 Durnal Radio 20.60 000132A9C9 M 17-Sep-95 Durnal Radio 20.40 000132E8DA M 17-Sep-95 D urnal Radio 0.00 000132A9C9 M 18-Sep-95 Durnal Radio 16.88 000132E8DA M 18-Sep-95 D urnal Radio 9.44 000132A9C9 M 19-Sep-95 Durnal Radio 0.00 000132A9C9 M 20-Sep-95 Durnal Radio 0.00 000132E8DA M 26-Sep-95 D urnal Radio 0.00 000132E8DA M 27-Sep-95 D urnal Radio 1.50 0001324E3CT M 17-Jun-97 Durnal Radio 9.50 0001324E3CT M 18-Jun-97 Durnal Radio 63.60 000133285CT M 18-Jun-97 D urnal Radio 9.20 0001324E3CT M 19-Jun-97 Durnal Radio 95.10 000133285CT M 19-Jun-97 D urnal Radio 0.00 0001324E3CT M 4-Jul-97 Durnal Radio 12.18 000133285CT M 4-Jul-97 Durnal Radio 8.37 0001324E3CT M 5-Jul-97 Durnal Radio 22.85 000133285CT M 5-Jul-97 Durnal Radio 0.00 Continued next page.
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Table 5 (continued). 00013246C0T M 16-Jul-97 D urnal Radio 0.00 0001324E3CT M 16-Jul-97 Durnal Radio 9.50 000133285CT M 16-Jul-97 D urnal Radio 0.00 00013246C0T M 17-Jul-97 D urnal Radio 0.25 000133285CT M 17-Jul-97 D urnal Radio 0.00 00013246C0T M 23-Jul-97 D urnal Radio 22.18 00013246C0T M 24-Jul-97 D urnal Radio 18.70 000133285CT M 24-Jul-97 D urnal Radio 4.25 00013246C0T M 25-Jul-97 D urnal Radio 0.00 00013246C0T M 26-Jul-97 D urnal Radio 0.00 000133285CT M 26-Jul-97 D urnal Radio 14.60 00013246C0T M 27-Jul-97 D urnal Radio 11.13 000133285CT M 27-Jul-97 D urnal Radio 0.00 00013246C0T M 23-Aug-97 Durnal Radio 1.11 00013246C0T M 24-Aug-97 Durnal Radio 0.00 00013246C0T M 25-Aug-97 Durnal Radio 0.00 000133285CT M 25-Aug-97 Durnal Radio 0.00 00013246C0T M 26-Aug-97 Durnal Radio 0.75 000132C94A F 25-Aug-95 Nocturnal Radio 71.90 000132F3C3 F 27-Sep-95 Nocturnal Radio 0.00 000132F3C3 F 28-Sep-95 Nocturnal Radio 5.80 00013263BDT F 18-Jun-97 N octurnal Radio 5.55 00013263BDT F 4-Jul-97 N octurnal Radio 16.55 00013263BDT F 16-Jul-97 N octurnal Radio 0.00 00013263BDT F 23-Jul-97 N octurnal Radio 31.60 00013263BDT F 24-Jul-97 N octurnal Radio 43.52 0001333EBFT F 24-Jul-97 N octurnal Radio 13.00 00013263BDT F 25-Jul-97 N octurnal Radio 0.00 0001333EBFT F 25-Jul-97 N octurnal Radio 17.15 00013263BDT F 26-Jul-97 N octurnal Radio 0.00 0001333EBFT F 26-Jul-97 N octurnal Radio 12.48 00013263BDT F 27-Jul-97 N octurnal Radio 38.43 0001333EBFT F 27-Jul-97 N octurnal Radio 15.10 000132A9C9 M 25-Aug-95 Nocturnal Radio 0.00 000132E8DA M 25-Aug-95 Nocturnal Radio 2.90 000132E8DA M 15-Sep-95 N octurnal Radio 120.40 000132A9C9 M 16-Sep-95 Nocturnal Radio 2.85 000132A9C9 M 16-Sep-95 Nocturnal Radio 31.60 000132E8DA M 16-Sep-95 Nocturnal Radio 0.00 000132A9C9 M 17-Sep-95 Nocturnal Radio 0.00 000132E8DA M 17-Sep-95 Nocturnal Radio 0.00 000132A9C9 M 18-Sep-95 Nocturnal Radio 0.00 000132E8DA M 18-Sep-95 Nocturnal Radio 0.00 000132A9C9 M 19-Sep-95 Nocturnal Radio 0.00 000132E8DA M 19-Sep-95 Nocturnal Radio 0.00 000132E8DA M 25-Sep-95 Nocturnal Radio 1.50 Continued next page.
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Table 5 (continued). 000132E8DA M 26-Sep-95 Nocturnal Radio 0.00 000132E8DA M 27-Sep-95 Nocturnal Radio 0.00 0001324E3CT M 17-Jun-97 Nocturnal Radio 6.93 0001324E3CT M 18-Jun-97 Nocturnal Radio 10.28 000133285CT M 18-Jun-97 Nocturnal Radio 85.22 0001324E3CT M 4-Jul-97 Nocturnal Radio 36.63 000133285CT M 4-Jul-97 Nocturnal Radio 7.72 00013246C0T M 16-Jul-97 N octurnal Radio 0.00 0001324E3CT M 16-Jul-97 Nocturnal Radio 0.44 000133285CT M 16-Jul-97 N octurnal Radio 17.25 00013246C0T M 23-Jul-97 N octurnal Radio 30.85 000133285CT M 23-Jul-97 N octurnal Radio 38.50 00013246C0T M 24-Jul-97 N octurnal Radio 0.00 000133285CT M 24-Jul-97 N octurnal Radio 13.25 00013246C0T M 25-Jul-97 N octurnal Radio 0.00 00013246C0T M 26-Jul-97 N octurnal Radio 0.00 000133285CT M 26-Jul-97 N octurnal Radio 14.60 00013246C0T M 27-Jul-97 N octurnal Radio 0.00 000133285CT M 12-Aug-97 Nocturnal Radio 14.20 00013246C0T M 23-Aug-97 Nocturnal Radio 0.00 00013246C0T M 24-Aug-97 Nocturnal Radio 0.00 000133285CT M 24-Aug-97 Nocturnal Radio 13.95 00013246C0T M 25-Aug-97 Nocturnal Radio 0.00 000133285CT M 25-Aug-97 Nocturnal Radio 13.95 0001DA5A76T F 28-Jun-96 Durnal String 1.22 0001DA5A76T F 29-Jun-96 Durnal String 25.60 0001DA5A76T F 30-Jun-96 Durnal String 3.22 000132A698T F 1-Jul-96 Durnal String 2.00 0001DA5A76T F 1-Jul-96 Durnal String 4.49 0001DA5A76T F 2-Jul-96 Durnal String 0.27 00013263BDT F 17-Jun-97 D urnal String 48.65 00013263BDT F 18-Jun-97 D urnal String 67.47 000132AFC6T M 30-Jun-95 D urnal String 18.07 000132AFC6T M 1-Jul-95 Durnal String 53.99 O001326619 M 26-Sep-95 Durnal String 6.73 O001326619 M 27-Sep-95 Durnal String 5.10 O001326619 M 28-Sep-95 Durnal String 10.29 O001326619 M 29-Sep-95 Durnal String 45.32 O001326619 M 30-Sep-95 Durnal String 12.79 000133C20AT M 28-Jun-96 Durnal String 2.40 0001DB586AT M 28-Jun-96 Durnal String 1.51 000133C20AT M 29-Jun-96 Durnal String 68.97 0001DB586AT M 29-Jun-96 Durnal String 8.09 000133C20AT M 30-Jun-96 Durnal String 5.96 0001DB586AT M 30-Jun-96 Durnal String 86.66 000133C20AT M 1-Jul-96 Durnal String 49.02 Continued next page.
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Table 5 (continued). 00013246C0T M 17-Jun-97 Durnal String 25.42 000133285CT M 17-Jun-97 Durnal String 48.06 00013246C0T M 18-Jun-97 Durnal String 73.16 000133B300T M 26-Jul-97 Durnal String 14.24 00013284D2T M 27-Jul-97 D urnal String 13.37 000133B300T M 27-Jul-97 D urnal String 0.00 0001DA5A76T F 28-Jun-96 Nocturnal String 0.00 0001DA5A76T F 29-Jun-96 Nocturnal String 0.00 000132A698T F 30-Jun-96 Nocturnal String 76.43 0001DA5A76T F 30-Jun-96 Nocturnal String 7.66 000132A698T F 1-Jul-96 Nocturnal String 88.12 0001DA5A76T F 1-Jul-96 Nocturnal String 8.76 00013263BDT F 17-Jun-97 N octurnal String 1.48 000132AFC6T M 30-Jun-95 Nocturnal String 37.23 O001326619 M 27-Sep-95 Nocturnal String 5.09 O001326619 M 28-Sep-95 Nocturnal String 19.39 O001326619 M 29-Sep-95 Nocturnal String 12.78 O001326619 M 30-Sep-95 Nocturnal String 34.71 000133C20AT M 28-Jun-96 Nocturnal String 0.00 0001DB586AT M 28-Jun-96 Nocturnal String 0.00 000133C20AT M 29-Jun-96 Nocturnal String 84.54 0001DB586AT M 29-Jun-96 Nocturnal String 0.00 000133C20AT M 30-Jun-96 Nocturnal String 25.62 0001DB586AT M 30-Jun-96 Nocturnal String 27.39 00013246C0T M 17-Jun-97 Nocturnal String 0.00 000133285CT M 17-Jun-97 N octurnal String 110.07 000133B300T M 26-Jul-97 Nocturnal String 42.46 00013284D2T M 27-Jul-97 N octurnal String 14.02 000133B300T M 27-Jul-97 N octurnal String 100.14
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9 259.36 43.293 0.000 df Mean Square F Sig. † pe III y T Sum of Squares of Sum Sex 101.177 3 33.726 5.63 0.001 ErrorTotal 970.521 11978.31 162 172 5.991 Source Intercept 262.669 1 262.669 43.845 0.000 Habitat TypeHabitat 611.718 2 305.859 51.054 0.000 Corrected TotalCorrected 3304.762 171 Corrected ModelCorrected 2334.241 Sex X Habitat Type Habitat X Sex 31.287 3 10.429 1.741 0.161 R Squared = 0.706 (Adjusted R Squared = 0.690) = Squared R (Adjusted 0.706 = Squared R Days Since Breeding Since Days 239.856 1 239.856 40.037 0.000
Table 6. Distribution analysis (ANCOVA) for toads captured in the three principal meadows of the of the HLMC. principal in meadows the captured for three toads (ANCOVA) 6. analysis Table Distribution center. meadow from of distance Square-root Variable: Dependent of start breeding. since Days Covariate: † Intercept Design: Sex+ Habitat + Type Days+ Since Breeding Sex + X Habitat Type.
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dispersal B. canorus B. 95% Confidence Interval 95% Lower Bound Upper Bound Estimated marginal means for square-root of of square-root for means marginal Estimated Juveniles 6.564* 1.086 4.420 8.708 Subadults 6.840* 0.978 4.910 8.771 Sex ClassSex Mean Error Std. Adult MalesAdult 9.186* 0.689 7.825 10.546 Adult FemalesAdult 9.338* 0.744 7.869 10.807 Table 7. 30.23. at evaluated is model the in appearing Breeding, Since Days covariate, The * distance by sex/age bydistance sex/age class.
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† Difference 95% Confidence95% Interval for Lower BoundLower Bound Upper † Std. ErrorStd. Sig. - sex/age classes. sex/age J) Mean Mean B. canorus B. Difference (I Juveniles 0.276 0.679 0.685 -1.065 1.618 Juveniles 2.774* 0.756 0.000 1.281 4.267 Juveniles 2.622* 0.713 0.000 1.214 4.030 Subadults -0.276 0.679 0.685 -1.618 1.065 Subadults 2.497* 0.640 0.000 1.234 3.761 Subadults 2.245* 0.588 0.000 1.184 3.507 Adult FemalesAdult -2.497* FemalesAdult 0.64 -2.774* 0.000 0.756 0.000 -3.761 -4.267 -1.234 -1.281 Pairwise Pairwise comparisons of (I) Sex (J) Sex Juveniles Males Adult -2.622* 0.713 0.000 -4.03 -1.214 Subadults Males Adult -2.345* 0.588 0.000 -3.507 -1.184 Adult MalesAdult Females Adult -0.152 0.484 0.753 -1.107 0.803 Adjustment for multiple comparisons: Least Significant Diffrence (equivalent to no adjustments). to no (equivalent Diffrence Least Significant comparisons: multiple for Adjustment Adult FemalesAdult Males Adult 0.152 0.484 0.753 -0.803 1.107 Table 8. traveled. square-root distance variable: of Dependent means. marginal estimated on Based 0.05 level. the at significant difference is mean The * †
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95% Confidence Interval Confidence 95% dispersal distance by habitat type. type. habitat by distance dispersal Lower BoundLower Bound Upper B. canorus B. Estimated marginal means for square-root of of square-root for means marginal Estimated Upland 12.894* 0.726 11.462 14.327 Meadow 5.836* 0.219 5.404 6.268 Overwintering 5.216* 1.966 1.333 9.098 Habitat TypeHabitat Mean Error Std.
Table 9. 30.23. at evaluated theis model in appearing Breeding, Since Days covariate, The *
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† Difference 95% Confidence Interval for Interval Confidence for 95% Lower BoundLower Bound Upper † Std. ErrorStd. Sig. habitat types. types. habitat (I-J) Mean Difference B. canorus B. Type Upland -7.679* 1.76 0.000 -11.153 -4.204 (J) Habitat Overwintering 0.620Overwintering 7.679* 1.989 1.760 0.756 0.000 -3.307 4.204 4.547 11.153 Pairwise comparisons of comparisons Pairwise Type Upland Meadow 7.059* 0.760 0.000 5.559 8.558 Meadow Upland -7.059* 0.760 0.000 -8.558 -5.559 (I) Habitat Habitat (I) Overwintering Meadow -0.620 1.989 0.756 -4.547 3.307 Adjustment for multiple comparisons: Least Significant Diffrence (equivalent to no adjustments). to no (equivalent Diffrence Least Significant comparisons: multiple for Adjustment Table 10. Table traveled. distance square-root of variable: Dependent Base d on est imated marginal 0.05 level. the at means. significant difference is mean The * †
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Habitat Overwinter Upland Upland Habitat Habitat Meadow Meadow Habitat in Uplandin Adult MalesAdult Habiat in Upland Adult Fem. Upland Upland Habitat Adults in Toads All Adult dispersal distances for groupings of various life stages and habitat types. habitat and life stages various of groupings for distances dispersal Adult Adult Males Adult Adult Females B. canorus Juveniles Subadults All All 172 21 37 40 74 114 16 6 10 148 21 3 Descriptive statistics of Toads n Mean 69.64 33.97 61.12 77.04 80.02 78.97 278.60 221.61 312.79 39.26 265.93 194.31 95% CI95% 83.99 44.55 85.27 102.3 108.09 98.99 361.36 294.83 444.76 44.98 328.25 312.86 Minimum 2.22 6.56 2.22 2.61 3.15 2.61 106.34 106.34 152.45 2.22 106.34 141.77 Std. ErrorStd. 7.27Maximum 657.44 5.07 66.27 11.91 257.39 279.45 12.49 657.44 14.08 657.44 10.1 657.44 279.45 38.83 657.44 28.48 185.59 657.44 58.34 234.96 2.89 29.88 27.55 Table 11.
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Reference Breeding Site Migration Distance From Texas m 31-72 (1953) Blair Spain 700 m w/in 95% Japan (2000) al. et Miaud m 27-260 (1995) al. et Kusano Kansas m 579 Fitch (1958) Ontario m 23-480 (1966) Oldham Germany m 55-1600 (1988) Sinsch Germany m 2000 (1997) Sinsch Wyoming m 101 (1954) Carpenter Minnesota m 1000 (1969) Ewert MinnesotaMinnesota m 300-1300 61 m (1969) Ewert (1961) Tester and Breckenridge New GuineaNew m150 = Mean (1979) Zug and Zug Idaho RockiesIdaho m 940 Male m; 2440 Fem. (2004) al. et Bartlet California SierraCalifornia SierraCalifornia m 150-230 m 750 Females (1980) Sherman Kagarise (1981) Morton Colorado RockiesColorado RockiesColorado m 970.8 Male m; 2324.3 Fem. m 900 (2003) Muths (1970) Campbell Species Location Range and/or maximum migration distance from breeding site to foraging habitat for various Bufonid species. Bufonid various for habitat to foraging site breeding from distance migration maximum and/or Range Bufo bufo Bufo Bufo boreas Bufo boreas Bufo boreas Bufo boreas Bufo canorus Bufo canorus Bufo Bufo marinus Bufo calamita Bufo Bufo calamita Bufo Bufo valliceps Bufo Bufo cognatus Bufo Bufo americanus Bufo americanus Bufo Bufo hemiophrys Bufo Bufo woodhousei Bufo Bufo japonicus furmosus Table 12. Table listed. Bufonids the for meters 925±199 is distance dispersal maximum of mean The
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FIGURES
Figure 1. Highland Lakes Meadow Complex (HLMC) base map.
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Figure 2. North pools breeding site on 27 June 1996. Principal breeding took place in the shallows in the center of the photograph that is clear of snow.
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Figure 3. North pools meadow looking south to north Highland Lake toward the end of breeding season on 28 June 1996. The main breeding pool is located in the depression to the center left of the picture below the snow bank. Note the rapidity of the melting of the snow from the previous day (Figure 2), which results in snowmelt sheet-flows.
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Figure 4. Mid pools meadow breeding pools. The semi-stable banks suggest that these pools may have a kettle sink origin. Note the chiseling of the banks, which decreases their stability, wrought by cattle drinking from the pools.
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Figure 5. Tryon meadow B. canorus breeding site. Toads breed in the shallow pool
in the center right of the photograph (see Figure 6), but few eggs hatch at this location, and none of the larvae survive to metamorphosis. Note the erosion of the stream banks caused by stock grazing and the resulting down-cutting of the stream channel, which has lowered the water table of the meadow.
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Figure 6. Shallow B. canorus egg mass located at Tryon meadow breeding site (see Figure 5) on 27 June 1996. None of the larva from this egg mass survived more than a few weeks.
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Figure 7. Tryon meadow breeding pool on 16 July 1996. Although several egg masses were spawned in this pool, trampling by stock, which were not present the previous season, altered the topography of the breeding pool sufficiently to make survival of larva to metamorphosis unlikely. Metamorphosis was made impossible when the altered topography was combined with the lowering of the water table resulting from stream channel erosion.
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Figure 9. Female Yosemite toad (F-00013263BDT) with a radio transmitter package attached by plastic belt. Note how the radio package sits low on the back, and the antenna trails behind to minimize snagging in vegetation and burrows.
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Figure 10. Male Yosemite toad with cocoon bobbin thread-tracking device
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Figure 11. Tryon meadow, Highland Lakes Meadow Complex. Position and movements of PIT tagged toads.
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Figure 12. North pools meadow, Highland Lakes Meadow Complex. Position and movements of PIT tagged toads.
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Figure 13. Mid pools meadow toad movements, Highland Lakes.
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Figure 14 (following page). Comparison between the actual path traveled by Yosemite toads as indicated by string pouch (left) and the estimated path toads traveled as would be indicated from radio tracking data (right). A--Male (00013284D2T) tracked from 27 July to 28 July 1997 in North Pools upland habitat. B--Male (00013246C0T) tracked from 17 June to 18 June 1997 in North Pools breeding habitat. C--Female (0001DA5A76T) tracked from 28 June to 2 July 1996 in Mid Pools meadow habitat. D--Male (O001326619) tracked from 26 September to 29 September 1995 in Mid Pools upland habitat. E--Male (0001DB586AT) tracked from 28 June to 1 July 1996 in North Pools leaving breeding pools for foraging habitat. F--Male (000133B300T) tracked from 26 July to 27 July 1997 foraging in North Pools meadow habitat. G--Male (000132AFC6T) tracked from 30 June to 1 July 1996 in Mid Pools meadow foraging habitat. H--Female (00013263BDT) tracked from 17 June to 19 June 1997 leaving North Pools breeding pools for upland foraging habitat. I--Male (000133C20AT) tracked from 28 June to 1 July 1996 in North Pools meadow, in and leaving breeding pools. J--Female (000132A698T) tracked from 30 June to 2 July 1996.
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Figure 15. Scatter plot with fitted regression line of the relationship between string- track travel distance and the estimated travel distance that would have been obtained had the same B. canorus been radio-tracked.
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Figure 16. Scatter plot with fitted regression line of the relationship between home range estimates for string-tracked and radio-tracked Bufo canorus.
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Figure 17. Overwintering site (1995-96) for male (000132E8DA) B. canorus in burrow under orange flag in center of photo. This photo was taken on 27 June 1996 during snow melt at the start of breeding season. Note the snow has melted from beneath the trees where the overwintering burrow is located whereas the snow has not melted from the willows located to the top left of the photo.
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Figure 18. Overwintering site (1995-96) for female (000132F3C3) B. canorus in burrow under rock pile in center of photograph where orange pin-flag is located. This photo was taken on 27 June 1996 during snow melt at the start of breeding season. This burrow is located on the bank of a dry wash (to the right of photo) under the forest canopy.
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23-Oct
18-Oct 13-Oct
8-Oct
3-Oct
28-Sep
23-Sep
18-Sep
13-Sep 8-Sep
3-Sep
29-Aug
24-Aug
19-Aug 14-Aug
1995
9-Aug 4-Aug
30-Jul
25-Jul
20-Jul
15-Jul
10-Jul
5-Jul 30-Jun
25-Jun
20-Jun 15-Jun
5.0 0.0
-5.0 25.0 20.0 15.0 10.0
-10.0 Temperature (C) Temperature
Figure 19. Daily temperature range for mid pools meadow, Highland Lakes, during the 1995 active season. Data source: State of California, Department of Water Resources, automated Snow Course Survey weather station data.
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Figure 20. Overwintering site (1995-96) of male (000132A9C9) located on the southeast slope of Folger Peak in the lodgepole pine forest, west of mid pools meadow, HLMC. The east facing burrow entrance is located at the bottom center of the photo at the tip of the blue tripod case.
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Figure 21. Excavated overwintering site of male 000132A9C9 early in the active season before much vegetative growth had occurred. The burrow was a 130 cm long blind ending tunnel that was 6-7 cm in diameter with a 25 cm long side tunnel (near orange stake). The chamber at the end of the long tunnel was 35 cm beneath the ground surface.
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Figure 22. String-track breeding range of male (000133C20AT) B. canorus on east edge of north pools breeding site. This photograph was taken on 30 June 1996 during the mapping of the string-track. Orange pin-flags denote points where toad direction changes. The yellow flagging was laid down over the string-track for photographing.
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Figure 23. Nocturnal string-track of B. canorus male (000133285CT) traveling north from north pools meadow. This photograph was taken on 18 June 1997 during the mapping of the string-track. Orange pin-flags denote points where toad direction changes. The white measuring tape was laid down over the string-track for photographing. After leaving the meadow the toad traveled in the ditch to the right of the road and rested in a burrow under the rock indicated with the red arrow near the top of the photograph.
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Figure 24. Differences in movement distances between diurnal (10am-10pm) and nocturnal periods for radio-tracked and string-tracked Bufo canorus. There is no significant difference between diurnal and nocturnal movements, but there is a significant difference (p<0.001) in the distances traveled by radio vs. string-tracked toads. Bars represent x and SD of distance traveled, and numbers in bars represent n.
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Figure 25. Upland habitat occupied by male (O001326619) on 28 September 1995. This habitat is located northwest of mid pools meadow, Highland Lakes, on the southwest facing slope of Folger Peak. Toad is located at the base of the willow in the center of photograph marked with the “X”.
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Figure 26. Burrow under base of willow (Salix sp.) utilized by Bufo canorus female in upland habitat located on the southeast slope of Folger Peak.
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Figure 27. Upland habitat occupied by male toad (000133C20AT) on 16 July 1996. Note toad is located in burrow under boulder in center front marked “X”. Breeding pools are located in the upper left of the photo blocked from view by trees marked with the red circle. Toad traveled up the wash to the right of the circle and foraged in the willows in the center of the photograph. Overland movements occurred at night.
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Figure 28. Dispersal distance from breeding pool center for each of the four sex
classes. Sample size is 74, 40, 37 and 21 for adult males, adult females, subadults and juveniles respectively.
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Figure 29. Distance measurements in meters from meadow center to toad location classed according to habitat type.
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Figure 30. Dispersal vector plot for all B. canorus captured in all three study meadows.
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Figure 31. Dispersal vector plots for all three study meadows superimposed on the HLMC base map.
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Figure 32. Expected fraction of toad population contained within a specified distance from the breeding pool center.
232
Figure 33. Dispersal distance from breeding pool center to toad location for each of the sex classes. Ellipses represent a 95% confidence interval for the corresponding sex class.
233
Figure 34. Dead yearling B. canorus located in the center (within red circle) of a cattle hoof print in north pools meadow, HLMC. Most toads killed by trampling are difficult to locate owing to the bodies generally being buried and/or dismembered.
234
Figure 35. HLMC base map with 450 m core habitat protection zone and 50 m core habitat buffer zone superimposed. Note that this map contains core habitat protection zones for all known local population breeding sites occurring within the HLMC study area.
235
APPENDIX I in ture g p Notes Center ¥ Center hland Lakes Meadow Lakes hland Distance From g 13.4 169.03 Farthest From Bearing Bearing Center ° 112 57.91 54.811 77.21 58.04 113.81 55.43 242.51 113.61 61.28 125.69 76.11 73.07 249.51 Ori 124.37 88.1 90.9 60.53 79.37 53.4 Reca 82.25 85.48 61.07 Type ¤ Type Habitat Habitat al in meadows the Hi p 4 4 4 4 4 4 4 4 4 4 4 4 rinci p Site § ID 41 41 91 inthe three Days Since Breeding † 6 6 6 -95-95 37 37 1 1 -95-95 60 58 1 1 g g p p . canorus B tured tured p Distribution of ca 17181920 0001BBDEF423 RF4 000132F188 3 3 000132E800 17-Aug-95 LFP 4 17-Aug-95 3 29 17-Aug-95 25-Aug-95 4 29 29 24-Aug-95 15 37 15 36 15 1 15 1 15 1 328.3 1 329.1 253.5 1 26.37 36.6 24.99 15.52 26.1 2.22 8.47 22 0001BBD55B 2 25-Au 27 0001DAD7E8 4 15-Se 24 000132C94A9595 2 000132D697T 25-Au 000132D697T 1 1 27-Jun-9 8-Jun-97 4 1 24 000132C94A 2 17-Se 96 0001332907T 2 27-Jun-9 111145146 0001DB6736T147 000133D102T 2148 0001BBDE3BT149 1 2 0001324E72T150 2-Jul-9 00013427E8T174 2 8-Jun-97 0001DA5C5AT 8-Jun-97175 1 000132A9A0T 1176 8-Jun-97 000133E46FT 1177 4 16-Jun-97 0001326C33T 16-Jun-97 4178 2 0001323118T 16-Jun-97179 2 4 000133D600T 12179 12 1 8-Jun-97 0001336ACBT 1 180 1 8-Jun-97 12 1 0001336898T 2 8-Jun-97 0001336898T 1 1 4 8-Jun-97 1 0001BBE12FT 14 8-Jun-97 4 1 14 2 4 8-Jun-97 13-Aug-97 4 1 4 14 8-Jun-97 14 1 4 70 14 230 14 4 1 14 227.7 1 14 14 1 44.92 93.1 1 14 43.79 1 94.2 2 93.7 1 98.22 55 53.6 1 100.35 132.8 110.5 99.28 110.2 59.01 58.78 657.44 122.57 121.29 Farthest Origin endix 1. endix pp AnimalNo. ? Pit Tag/Toe Clip Sex * Date A Continued next page next Continued
236
in g d d d ture ture ture p p p lan lan lan p p p ture/Ori Notes p Center ¥ Center Distance From From Distance 76 208.15 U 135 172.99 Farthest 74.373.3 197.10 204.94 U U From Bearing Bearing Center ° 2 2 2 2 Type ¤ Type Habitat Habitat Site ID § s Sinces y Da Breeding † -95 38-95 27 15 15 1 275.7 34.47 g g Sex * Sex Date p . ) ed 2 30-Jun-96 7 15 1 170.9 9.09 gg /Toe Cli g continued (
949494 0001324E3CT94 0001324E3CT97 1 0001324E3CT97 1 0001324E3CT98 1 29-Jun-96 0001DB586AT98 1 9-Jun-97 0001DB586AT 199 17-Jun-97 0001D AD52BT 17-Jul-97 5 0001DAD52BT 1 28-Jun-96 6 13 1 1 0001324A89T 43 1-Jul-96 5 29-Jun-96 28-Jun-96 15 1 15 15 28-Jun-96 15 6 8 5 15 1 1 1 1 5 15 220.6 1 15 15 177.9 208.6 35.3 18.37 15 1 268 1 9.83 9.74 1 185.59 167 1 Recapture/Origin 18.33 66.6 Recapture 57.9 Farthest Mdw. Origin 13.1 9.00 35.98 15.69 Origin 4.78 Mdw. Reca Fart hest 92 000133C20AT 1 29-Jun-96 9 15 9394 0001DAD5F3T 0001324E3CT 1 1 27-Jun-96 27-Jun-96 4 4 15 15 1 1 359.5 165.3 3.15 7.47 Reca 26 00D13204B1 1 26-Au 535589 0001DA5CFA 0001DB5627 3 0001DB6823 3 17-Oct-95 1 17-Oct-95 15-Au 90 90 15 15 919292 00013256C0T 000133C20AT 000133C20AT 1 2 1 27-Jun-96 27-Jun-96 28-Jun-96 4 4 5 15 15 15 1 1 1 71 65.5 351.4 18.35 16.70 13.63 Reca 105106 0001DB577ET 00013246C0T 1 1 30-Jun-96 29-Jun-96 7 4 15 15 1 1 172.8 53 11.72 21.92 Recapture 100102 000133CD32T 1 Unta 28-Jun-96 5 15 1 6.8 19.92 103104104 0001DA59B0T 0001335B1AT 1 0001335B1AT 1 30-Jun-96 1 29-Jun-96 8-Jun-97 7 4 6 15 15 15 1 1 1 56.6 58.4 171.8 40.56 42.57 9.90 Reca endix 1. 1. endix pp AnimalNo. ? Pit Ta A page next Continued
237
in g ture p in g ture/Ori Notes p Center ¥ Distance From From Distance 79.7 210.72 Farthest 79.885.2 211.08 233.85 Farthest Farthest From 332.9 631.40 Farthest Bearing Center ° 2 2 2 2 Type ¤ Type Habitat Habitat Site ID § s Since y Breeding † Da -97 84-97-97-97 15 84-97 84-97 84-97 84 15 84 15 84 15 15 1 15 1 15 1 89.6 1 93.4 1 96.6 1-97 94.2 56.09 100.7 59.17 110.3 57.11 83 59.89 59.13 55.00 15 g g g g g g g g Sex * Sex Date p . ) /Toe Cli g continued (
106 00013246C0T 1 17-Jun-97 13 15 1 178.5 17.71 Reca 107112113 000132504ET114 00013247C3T 1 000133F7DFT 1 1 30-Jun-96 RF2 2-Jul-96 2-Jul-96 7 9 4 9 27-Au 15 15 15 1 1 1 169.3129 87.8 62.8 5.17 130 0001333EBFT 36.44 2 51.16 000133B300T 1 8-Jun-97 9-Jun-97 4 5 15 15 1 1 53.2 226 20.04 10.30 Ori Capture First 106 00013246C0T 1 8-Jun-97 6 15 1 179.2 8.38 Ca First 106 00013246C0T 1 27-Au 128 00013284D 2T 1 27-Jul-97 53 15 129 0001333EBFT 2 26-Jul-97 52 15 115116117 000133EF99T118 0001323109T119 3 000133C0F4T120 3121 27-Au 122 3 27-Au RF2123 RF2124 27-Au RF2125 RF2 4126 RF2 4127 RF2 000132DE00T 27-Au 4127 RF2 27-Au 00013362FET 4 3127 27-Aug-97 4 000133285CT 3 27-Aug-97 4 000133285CT 23-Aug-97 1 27-Aug-97 4 000133285CT 84 26-Aug-97 1 27-Aug-97 84 80 1 9-Jun-97 27-Aug-97 84 17-Jun-97 83 84 26-Au 15 84 15 5 15 13 15 15 15 1 15 1 2 15 15 1 1 111.9 1 114.5 1 79.6 117.5 1 1 78.4 56.27 117.1 56.36 120.7 211.48 183.7 54.93 170 57.79 53.59 53.40 13.60 Upland 6.37 Recapture/Origin endix 1. endix pp Animal No. ? Pit Ta A Continued next page
238
in g ture p ture/Ori Notes p Center ¥ Distance From Distance From From Bearing Center ° Type ¤ Type Habitat Habitat Site § ID Days Since Breeding † 444 16-Jun-97 16-Jun-97 16-Jun-97 124 12 12 17-Jun-97 15 15 13 15 1 1 15 1 33.3 36.7 205.9 1 9.41 11.47 25.78 24 11.40 . ) ed 2 17-Jul-97 43 15 1 86.8 20.22 p p p p gg continued ( 154155156157161 RF 0001326402T162 RF 0001BBE5E0T163 2 1163 000132D3A7T164 16-Jun-97 RF 00013263BDT 16-Jun-97 1165 00013263BDT 2166 12 17-Jun-97 2167 12 17-Jun-97168 RF3 0001332741T 23-Aug-97170 RFp 13 00013250BCT171 15 1 13 15 2172 80 3173 17-Jun-97 RFp 4 15 19-Jun-97181 1 RF3 17-Jun-97 15182 1 RF3 15 17-Jun-97 13182 15 RF3 0001341EB4T 4 1 13 236.4 RF3 000133F402T 1 3 1 13 69 19-Jun-97 000133F402T 2 3 15 1 179.3 15 3 8-Jun-97 17-Jul-97 7.77 15 1 178.1 3 15 17-Jul-97 8-Jun-97 15 101.9 16.85 17-Jul-97 1 17.30 9-Jun-97 4 1 17-Jul-97 43 15.13 1 279.45 4 43 15 1 220.5 43 5 43.2 43 42.2 15 15 220.5 1 Origin 15 Farthest 17.27 15 15 13.48 15 34.92 15 1 20.28 1 31.5 1 1 1 1 51.6 1 81.6 10.61 19.2 81.7 82.6 178.8 19.96 82.7 21.01 54.20 21.29 13.16 21.38 21.75 Recapture 151152152 0001BBDEF4T RF3 0001BBDEF4T 1 1 16-Jun-97 3 17-Jun-97 12 16-Jun-97 13 12 15 15 15 1 1 172.4 1 176.6 173.9 7.29 16.13 14.60 Reca 130 000133B300T 1 26-Jul-97 52 15 1 38.8 119.54 Reca 130144 000133B300T 1 Unta 27-Jul-97 53 15 1 45.6 128.99 Farthest Mdw. 153 RF endix 1. 1. endix pp Animal No.Animal ? Pit Tag/Toe Clip Sex * Date A Continued next page
239
Notes Center ¥ Center Distance From Distance From From Bearing Bearing Center ° Type ¤ Type Habitat Habitat Site § ID s Sinces y Da Breeding † -97-97 23 23 15 15 1 1 58.1 252.2 52.64 32.35 g g . ) ed 2 9-Jun-97 5 15 1 285.8 2.61 gg /Toe Clip Clip * /Toe Sex Date g continued (
161616 000132A9C92121 000132A9C9 1 000132A9C9 1 000132E8D A 16-Aug-95 1 000132E8D A 15-Oct-95 1 10-Dec-95 28 1 88 25-Aug-95 144 15-Sep-95 16 37 16 16 58 1 2 16 3 16 330.8 274.7 274.5 1 93.52 2 235.22 234.96 296.7 250.9 Origin Hibernacula Farthest 75.34 152.45 Origin Farthest 185197198 0001DA9ED9T199 000132F2B5T200 3 0001BBF470T 1 0001DB6823T 27-Au 1 1 9-Jun-97 Unta 9-Jun-97 9-Jun-97 5 5 5 15 15 15 1 1 1 214.1 21.4 221.9 23.55 6.82 17.27 202203204205206 RF3207 RF2208 RF3209 RF3210 3 RF3211 4 LF3212 3 17-Jul-97 RF3500 3 17-Jul-97 RF3501 3 17-Jul-97 RF3502 3 17-Jul-97 43 RF3 000132A698T503 3 17-Jul-97 501 43 RF3 Untagged 3 17-Jul-97 502 43 Untagged 3 2 17-Jul-97 2 503 43 Untagged 3 15 17-Jul-97 2 43 3 15 17-Jul-97 2 9-Jun-97 2-Jul-95 43 15 17-Jul-97 9-Jun-97 43 15 17-Jul-97 17-Jun-97 1 43 15 5 1 43 33 15 5 1 43 13 15 358.6 1 43 15 358.9 1 15 15 347.4 1 15 15 15 218.1 15 1 7.98 15 216.3 1 6.56 1 1 221 6.30 2 222.9 1 1 1 39.95 225.4 1 37.28 231.6 132.2 66.3 223.8 35.63 211.7 31.51 210 209.4 29.12 18.20 29.90 17.51 106.34 32.93 9.00 33.28 Farthest 183184 0001323D63T 0001BBD22DT 2 3 8-Jun-97 27-Au 4 15 1 53.6 22.60 endix 1. endix pp Animal No.Animal ? Pit Ta A Continued next page
240
land land land land p p p p Notes Center ¥ Center Distance From From Bearing Bearing Center ° Center 311 256.32 250.82 322.42 141.77 327.92 77.91 327.53 154.37 286.22 244.87 288.2 Hibernacula 2 257.39 294.41 268.44 319.41 272.57 319.3 U 206.22 232 U 329.06 241.5 U 330.50 Farthest Hibernacula 120.33 38.42 U Farthest Type ¤ Type Habitat Habitat 6 6 6 6 6 6 6 6 6 6 6 6 Site§ ID s Sinces y Breeding † Da -95 38 1 -95 28 1 -95-95-95 59-95 61 61 69-95 1 -95 1 1 69 1 71 1 1 g g p p p p p p . ) /Toe Clip Sex* Date g continued (
344646 0001326182 000132F3C3 348 000132F3C3 2 2 18-Se 26-Se O001326619 16-Oct-95 1 89 28-Se 1 252833 00013423C3 000132CC9B 2 00013419E3 346 26-Au 348 15-Se 18-Se 54 000132F3C3 O00132661990 2 1 000132485C 10-Dec-95 0001DAA92C 26-Se 3 1 144 20-Oct-95 16-Au 1 93 1 21 000132E8DA 1 10-Dec-95 144 1 101101108 0001DA5A76T109 0001DA5A76T 2109 2110 LR1 LF2, 000132AFC6T 28-Jun-96131 000132AFC6T 29-Jun-97 1132 00013421B3T 4 1133 5 30-Jun-96134 1 25 30-Jun-96135 1-Jul-96 RF3136 LF2 1-Jul-96 7136 16 LF3 7 16158 8 LF3 3 000133F746T159 LF3 8 4 000133F746T 2 16 1 0001326542T 3 1 5-Jul-97 16 2 3 16 5-Jul-97 1 9-Jun-97 3 5-Jul-97 320.4 16 LFp 1 313.6 31 5-Jul-97 5-Jul-97 16-Jun-97 1 31 5-Jul-97 1 5 108.97 31 358.5 112.83 1 4 31 12 31 358.3 16 31 311.9 16 16-Jun-97 Farthest Mdw. 16 355.5 72.49 16 Origin 66.27 16 16 1 16 100.41 12 16 1 54.40 1 1 Farthest Mdw. 40.3 Origin 1 1 1 41.6 1 16 54.1 27.4 226.6 18.2 17.10 282.1 25.6 12.86 1 17.97 7.92 9.10 63.14 8.46 25.20 240.8 Recapture 8.72 endix 1. endix pp AnimalNo. ? Pit Ta A page next Continued
241
Notes date of collection was was collection of date Center ¥ Distance From Distance From From Bearing Center ° Type ¤ Type Habitat Habitat Site§ ID 12 16 1 238.6 10.09 s Sinces y Da Breeding † 7 Sex * Sex Date p . ) ededed 2ed 1 2 9-Jun-97 1 9-Jun-97 9-Jun-97 5 9-Jun-97 5 5 5 16 16 16 16 1 1 1 68.4 1 56.3 54.6 61.4 23.18 27.11 27.68 34.54 gg gg gg gg /Toe Cli g continued (
160 LF3 3 16-Jun-9 193194195196 Unta Unta Unta Untagged 2 9-Jun-97 5 16 1 63.6 34.97 186187188 0001324BECT189 000132A155T 2190 00013352F6T191 1 000132D6A3T192 9-Jun-97 2 0001337B61T 2 9-Jun-97 000132AFC6T 1 9-Jun-97 1 5 9-Jun-97 Unta 5 9-Jun-97 9-Jun-97 5 5 16 5 16 5 16 16 1 16 1 16 1 68.4 1 44.1 1 1 40.5 60.4 17.80 58.5 22.35 71.5 22.41 21.80 18.25 23.78 endix 1. 1. endix pp Animal No. ? Pit Ta A ? Individual identification number used in the database. computer used number in identification ? Individual calculated. § SitID e isdefined as 14- TryonidentifiedHibernacula.as Upland, Meadow, 3- is and 2- 1- Habitat type ¤ meadow, 15- North pools meadow, and 16- Midpools meadow. * Sex of individual defined as 1- male, 2- female, 3- subadult and 4- juvenile. 4- and subadult 3- female, 2- male, 1- as defined individual of Sex * to breeding the of the since start days the of number years, conditions between in†environmental To differences for correct ofpointcenter capture. to from meadow Compass bearing ° ofpoint capture. center to meadow from in meters Distance ¥
242
APPENDIX II
243
Appendix 2. Bufo canorus tracking plots
0 50 100 m
Sex/Type Female Radio Track Start/Origin PIT Tag 000133EBFT Burrow Meadow North Pools Canyon, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 24 Jul 1997 to 12 Aug 1997
244
Appendix 2. Bufo canorus tracking plots
0 50 m
Sex/Type Male String Track Start/Origin PIT Tag 000133285CT Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 18 Jun 1997
245
Appendix 2. Bufo canorus tracking plots
0 50 100 200 m
Sex/Type Male Radio Track Start/Origin PIT Tag 00013246C0T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 27 Aug 1997
246
Appendix 2. Bufo canorus tracking plots
0 10 m
Sex/Type Male Radio Track Start/Origin PIT Tag 00013284D2 T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. C A Hibernacula From/To 27 Jul 1997 to 28 Jul 1997
247
Appendix 2. Bufo canorus tracking plots
0 30 m
Sex/Type Female String Track Start/Origin PIT Tag 00013263BDT Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 19 Jun 1997
248
Appendix 2. Bufo canorus tracking plots
X
0 50 100 m
Sex/Type Female Radio Track Start/Origin PIT Tag 00013263BDT Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 23 Aug 1997
249
Appendix 2. Bufo canorus tracking plots
0 50 100 m
Sex/Type Male Radio Track Start/Origin PIT Tag 00013246C0T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 27 Aug 1997
250
Appendix 2. Bufo canorus tracking plots
0 20 m
Sex/Type Male String Track Start/Origin PIT Tag 00013246C0T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 17 Jun 1997 to 18 Jun 1997
251
Appendix 2. Bufo canorus tracking plots
0 50 m
Sex/Type Male String Track Start/Origin PIT Tag 000133B300 T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. C A Hibernacula From/To 9 Jun 1997 to 17 Jul 1997
252
Appendix 2. Bufo canorus tracking plots
0 50 m
Sex/Type Female String Track Start/Origin PIT Tag 000132A698T Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 30 Jun 1996 to 2 Jul 1996
253
Appendix 2. Bufo canorus tracking plots
0 20 m
Sex/Type Male String Track Start/Origin PIT Tag 0001DB586AT Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 28 Jun 1996 to 1 Jul 1996
254
Appendix 2. Bufo canorus tracking plots
0 50 m
Sex/Type Male Radio Track Start/Origin PIT Tag 000133C20AT Burrow Meadow North Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 27 Jun 1996 to 1 Jul 1996
255
Appendix 2. Bufo canorus tracking plots
050 m
Sex/Type Female Radio Track Start/Origin PIT Tag 0001324E3CT Burrow Meadow Tryon, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 25 Aug 1995 to 17 Sep 1995
256
Appendix 2. Bufo canorus tracking plots
0 30 m
Sex/Type Female Radio Track Start/Origin PIT Tag 000132F3C3 Burrow Meadow Mid Pools, Folger Pk. slope End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 26 Sep 1995 to 10 Dec 1995
257
Appendix 2. Bufo canorus tracking plots
0 10 m
Sex/Type Female String Track Start/Origin PIT Tag 0001DA5A76T Burrow Meadow Mid Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 28 Jun 1996 to 2 Jul 1996
258
Appendix 2. Bufo canorus tracking plots
050 m
Sex/Type Male Radio Track Start/Origin PIT Tag 000132E8DA Burrow Meadow Mid Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 25 Aug 1995 to 10 Dec 1995
259
Appendix 2. Bufo canorus tracking plots
050100 m
Sex/Type Male Radio Track Start/Origin PIT Tag 000132A9C9 Burrow Meadow Mid Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 16 Aug 1995 to 10 Dec 1995
260
Appendix 2. Bufo canorus tracking plots
0 20 m
Sex/Type Male String Track Start/Origin PIT Tag 000132AFC6T Burrow Meadow Mid Pools, End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 30 Jun 1996 to 1 Jul 1996
261
Appendix 2. Bufo canorus tracking plots
0 20 m
Sex/Type Male String Track Start/Origin PIT Tag O001326619 Burrow Meadow Mid Pools, S. Slope of Folger Pk. End Location Highland Lakes, Alpine Co. CA Hibernacula From/To 27 Sep 1995 to 29 Sep 1995
262
CHAPTER III
HABITAT UTILIZATION OF THE YOSEMITE TOAD
(Bufo canorus, CAMP):
AN ENDANGERED ANURAN ENDEMIC TO THE
SIERRA NEVADA OF CALIFORNIA
263
INTRODUCTION
Amphibian species occupying montane habitats are taking on an increasingly important role in the study of Global Amphibian Decline owing largely to their mysterious population reductions in seemingly “protected” or “pristine” habitats
(Blaustein & Wake 1990; Wake & Morowitz 1990; Travis 1994; Blaustein & Wake
1995; Morrison & Hero 2003; Beebee & Griffiths 2005). One such species is the
Yosemite toad (Bufo canorus, Camp), a high-elevation Sierra Nevada endemic, that appears to have suffered a precipitous decline throughout its range for largely unknown reasons (Martin 1991a; Bradford & Gordon 1992; Kagarise Sherman &
Morton 1993; Jennings & Hayes 1994; Stebbins & Cohen 1995; Drost & Fellers
1996; Jennings 1996). This decline has resulted in the species being found to be
“warranted” for listing under the Endangered Species Act “but precluded by higher priority listing actions” (50 CFR 17 75834). Approximately 99% of the land within the range of this species is federally managed National Forests and National Parks
(Williams 2002) which are seemingly protected from overt habitat destruction; but the habitat needs of amphibians may be considerably different than those supposed by land managers (Pechmann et al. 1991; Beebee 1996; Dodd & Cade 1998; Alford &
Richards 1999; Semlitsch 2000, 2002; Semlitsch 2003a, b; Semlitsch & Bodie 2003;
Semlitsch & Rothermel 2003). In particular, the terrestrial habitat occupied by pool breeding amphibians, such as B. canorus, has been largely overlooked by land managers, in part because of the difficulty in detecting amphibians outside their
264
conspicuous breeding congregations (Martin et al. 1992; Brown 2002; Lind et al.
2006).
Mountain terrain, such as the high-elevation Sierra Nevada, is characterized by a topographically-diverse, highly-fragmented multitude of microhabitats distributed across a small geographic scale with large differences in habitat quality between patches (Korner 2002; Schabetsberger et al. 2004; Sztatecsny &
Schabetsberger 2005). Habitat utilization within this diverse region by pool-breeding anurans is further complicated by their use of different habitat patches for breeding, foraging and overwintering, that may be temporally and spatially separated (Wilbur
1980; Semlitsch 1981; Sinsch 1990). The upland foraging habitat is particularly important for amphibians whose population viability is often extremely sensitive to survivorship of life stages that utilize upland habitat (Biek et al. 2002; Vonesh & De la Cruz 2002; Storfer 2003). Thus, the aquatic and terrestrial habitats utilized by amphibians are linked by their life cycle functions and cannot be managed separately if amphibians are to survive in a particular region (Semlitsch 2000; Semlitsch &
Bodie 2003; Semlitsch & Rothermel 2003).
For these reasons, one of the first priorities for developing a biologically based recovery plan for B. canorus must be to quantify the terrestrial habitat patches utilized by this species. The resulting model, and the main goal of this chapter, can then be used to predict the core terrestrial habitat in need of protection during future management actions involving B. canorus.
265
METHODS
Study Animal
The Yosemite toad (Bufo canorus) is a montane toad endemic to the Sierra
Nevada Mountains of California that was first described by Dr. Charles Lewis Camp
in 1916 (Camp 1916). This toad demonstrates a striking degree of sexual
dimorphism in which the larger females have a mottling of black patches on a
grayish-white to light-tan ground color and the smaller adult male toads exhibit a
uniform coloration of olive-green to lemon-yellow (Stebbins 1951; Oliver 1955).
The color and pattern differences between the sexes of Bufo canorus have been
described as the “most pronounced instance of sexual dichromism among North
American anurans” (Stebbins 1951, p. 246; see also Oliver 1955).
This toad ranges from the Blue Lakes of Alpine County in the north
(Karlstrom 1962) to south of Evolution Lake in Fresno County near the crest of the
Sierra (Karlstrom 1962; Stebbins 1966). The west and east range limits of B. canorus
generally occur at elevations above 2,133 m and 2,438 m, respectively, with the
higher elevational limit in the eastern Sierra resulting from its steeper escarpment
(Karlstrom 1962) and “rain shadow” effect (Grinnel & Storer 1924; Storer & Usinger
1963). Karlstrom (1962) gives the known altitudinal range limits of B. canorus, as
1,950 m (Aspen Valley, YNP, Tuolumne Co.) to 3,444 m (Mt. Dana, YNP, Tuolumne
Co.), but he suggests the majority of locality records range from about 2,591 m to
3,048 m.
266
The post reproductive habitat occupied by B. canorus is generally described
as relatively open tundra-like wet meadows that are scattered throughout the Sierra
and are usually associated with alpine lakes or streams (Camp 1916; Grinnel & Storer
1924; Mullally 1953; Karlstrom 1962). Within these montane meadows, adult B.
canorus are reported to be common along the margins of lakes, shallow runoff streams and ephemeral pools and in close association with water where the meadow vegetation is generally deeper or more luxuriant than usual, or where there are patches of low willows that are used by the toads for cover (Grinnel & Camp 1917;
Grinnel & Storer 1924; Mullally 1953; Mullally & Cunningham 1956; Karlstrom
1962). In addition to willows, B. canorus are also reported to seek cover under surface objects such as logs and stones, but their preferred cover appears to be the subterranean burrows of rodents such as meadow voles (Microtus montanus) and pocket gophers (Thomomys monticola). These burrows are thought to provide protection from the cold temperatures at night in the high Sierra, as well as a moist microclimate that allows toads to inhabit the drier parts of the meadow away from open water (Stebbins 1951; Mullally 1953; Mullally & Cunningham 1956; Karlstrom
1962; see also Schwarzkopf & Alford 1996). However, Mullally (1953) noted that the movement of B. canorus within meadows was apparently restricted to areas near water, and Karlstrom (1962) reports that B. canorus is rarely found more than approximately 90 meters from permanent water. Despite this close association with water, according to Mullally and Cunningham (1956), B. canorus adults are rarely found within water after breeding has concluded, even though they are often observed beside water. Stebbins (1951) points out that the meadow habitats B. canorus seem
267
to prefer are generally surrounded by dry rocky terrain that this species rarely, if ever, inhabits thereby restricting toads to meadow habitat.
There are, however, a few anecdotal sightings of toads outside the meadow habitats in which they are thought to be restricted. Karlstrom (1962), for example, reports occasionally finding B. canorus adults in the margins of subalpine forests during the day, and there are several reports of B. canorus being found many meters away from meadows on the steeply sloping mountainsides where the vegetation is unusually rich or in bushy willow (Salix sp.) thickets that often concentrate beside ephemeral watercourses or seepages (Mullally 1953; Mullally & Cunningham 1956;
Karlstrom 1962; Kagarise Sherman 1980). Kagarise Sherman (1980), in particular, reports adult toads traversing distances of 150-230 m upslope to reach foraging habitat and hibernacula at the bases of willows (and consequently navigating the return trip each spring over snow drifts). Also, Morton (1981) reports finding several female B. canorus early in the active season, who had presumably just emerged from their hibernacula, 750 m from the closest major breeding site at the edge of a talus slope (near willows, pers. comm.), which was predominantly covered with snow at the time. The location of this particular hibernacula is also suggested by Mullally &
Cunningham (1956) and Kagarise Sherman & Morton (1984).
Thus, it is clear that B. canorus is capable of traveling relatively long distances from the wet meadows that these toads are believed to prefer to utilize entirely different habitat types. However, to date, no attempt has been made to quantify any of these terrestrial habitat types utilized by B. canorus, which have been largely overlooked by land managers but are likely required for long-term population
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viability (see, Wilbur 1980; Sinsch 1990; Biek et al. 2002; Vonesh & De la Cruz
2002; Semlitsch 2003b; Semlitsch & Bodie 2003; Semlitsch & Rothermel 2003;
Storfer 2003, see also Chapter 2), nor has there been any attempt to determine the
habitat features that can best be used to predict the core habitat utilized by B.
canorus. The current study is the first to examine the environmental and structural features of the post-reproductive habitat utilized by B. canorus.
Study Area
This study was conducted within the Highland Lakes meadow complex
(HLMC) in Stanislaus National Forest (NF), Alpine County, in the Sierra Nevada
Mountains of California. The HLMC is 5.9 km south of Ebbett’s Pass on State
Highway 4. This region is a glacial cut valley, with a northeast to southwest aspect
that appears to have been formed by the erosion of the headwall between two glacial
cirques. The paired kettles, named Highland Lakes, are the headwaters of two
different drainage basins separated by a moraine, with the larger northern lake
draining into the Mokelumne River Basin, and the southern lake draining into the
Stanislaus River Basin. The substrate within this valley is comprised predominately
of granitic till with thin peat soil development on the valley floor. There are eleven
large meadows within the Highland Lakes meadow complex (HLMC) where B.
canorus have been found, and many of these meadows supported breeding populations in the past; but breeding congregations only occurred in six of the meadows in 1994 (pers. obs.). For this study, I focused on one meadow, which I call
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north pools, containing ephemeral pools that have been used consistently by B.
canorus for reproduction since at least the 1960’s (McCreedy pers. comm.; pers. obs.).
The north pools meadow is located northeast of the northern lake downstream
from the lake out-flow (38.495° N, -119.797°W, 2,619 m). North pools is a wet
Nebraska Sedge class meadow (Ratliff 1982), but its hydrology is difficult to
characterize as it is located below the north lake rock dam, which was built to enlarge
the natural lake in 1952 (Albright et al. 1994) and appears to have altered the stream
flow through the meadow. Based on the topography of the meadow, the three
breeding pools appear to be located in the abandoned stream channel that eventually
confluents with the active stream channel (likely a second order stream), the North
Fork of the Mokelumne River. The main stream channel banks are severely eroded
along approximately 10 meters of its length to the east of the north ponds, but the
banks are stabilized downstream by low growing willows, and the channel becomes
incised with a couple of small erosional head-cuts located farther downstream within
the meadow. The breeding pools are shallow (< 0.5 m deep), typically ephemeral
pools that vary considerably in depth and surface area depending on snow-melt sheet-
flows early in the season, the water table of the meadow and precipitation recharge
late in the season, as there is no direct stream channel inflow to the pools at this time.
Thus, the longevity of the pools is dependent in large part on the depth of annual
snow pack in the surrounding area and the variation in the water table of the meadow.
The littoral zone of the pools, much like the rest of the meadow, is a dense sod of
predominately Nebraska sedge (Carex nebraskensis). This sedge is a valuable late
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season forage for cattle (Ratliff 1982) that have grazed the meadow almost every
summer since the 1860’s (Albright et al. 1994; Menke et al. 1996). The north pools
meadow at one time supported one of the largest breeding populations of B. canorus in the northern Sierra but the breeding population has since declined to approximately
50 to 100 individuals (McCreedy, pers. comm., pers. obs.).
Sampling
During July and August of 1997 the habitat utilized by B. canorus was quantified at 46 different locations where 17 individual toads were located after the breeding chorus had ceased. The habitat at an additional three (3) locations occupied by three (3) different toads (2 ♂; 1 ♀) that was utilized for overwintering during the
1995-96 winter was also surveyed during this study. In total the habitat locations sampled during this study included 18 meadow sites, 28 upland sites and the 3 overwintering sites, with 24 of these sites being occupied by males (number of sites surveyed per male, x =4.0±4.69, n=6), 15 by females (number of sites surveyed per
female, x =3.75±3.40, n=4), 2 by subadults (number of sites surveyed per subadult,
x =2.0±0, n=2) and 8 by juvenile toads (number of sites surveyed per juveniles,
x =8.0±0, n=8). Individual toad locations were determined via radio- and thread-
tracking (see chapter 2), by opportunistic collection while tracking toads and during
B. canorus population surveys in the north pools meadow. The three overwintering sites were included in this study as these are the only sites B. canorus are known to
have used for overwintering (toads were radio-tracked into their overwintering
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burrows where they remained until after snow fall, see chapter 2). In locations where more than one toad was found, such as in a shared burrow, the general habitat features were recorded once; and locations occupied by a particular individual on more than one occasion were also recorded only once to maintain the independence of the sample sites and decrease the likelihood that an aberrant individual would skew the data set (a truly random sample is unlikely to be obtained from nature, Reinert
1984); but the climatic micro-habitat variables were recorded on each occasion toads were encountered. There were, however, two (2) sub-adult and eight (8) juvenile toad locations in the north pools meadow where the habitat was quantified twice.
The first instance was when those individuals were first located in the sedges along the stream channel, and the second instance was eight days later after cattle had grazed the area and the sub-adults could no longer be located in that portion of the meadow. The second data set for these ten locations will only be used in a comparison with the previous data set to determine the changes in the microhabitat resulting from cattle grazing the area.
The habitat variables measured during this study (Appendix 3) follow those used in similar studies by James (1971), Reagan (1974), Dueser and Shugart (1978) and Reinert (1984); but the variables that I measured were stratified so as to sample both the macrohabitat of the general area about toad locations and the microhabitat at the point where individual toads were located. This stratification method was intended to gather data for habitat models that are useful for management at both the extensive (regional) and intensive (meadow) levels (see Morrison et al. 1992). The habitat variables quantified for this study meet the four criteria established by Dueser
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and Shugart (1978; see also Morrison et al. 1992). Namely, each variable was known or suspected to influence the distribution of B. canorus in some way. Each variable was easily measured without significant disturbance to or destruction of the habitat and was relatively stable during the active season of B. canorus, with the exception of weather parameters that help to determine individual activity patterns. Further, each of the variables selected and listed in Table 1 described in some way the environment in the immediate vicinity of the point of toad capture. The recording of time, date, age, sex and activity of the individuals at the locations surveyed enabled comparisons of these variables, and presumably the habitat they represent, among sexes, age classes, seasons and activity periods.
The habitat variables measured were divided into three independent habitat- sampling units centered on the study animal location. The first sampling unit consisted of general environmental variables associated with the microhabitat where the animal was located. The climatic variables, including air temperature taken 10 cm above the substrate, burrow air temperature (if the animal was located in a burrow or within 10 cm of a burrow entrance) and the temperature of the substrate within 5 cm of the animal were recorded immediately after a toad was located. These temperatures were taken with a thermocouple digital thermometer (TraceableTM;
Control Co.; with YSI® K-type thermocouple probe). The substrate type where the toad was located and the moisture level of the substrate were also recorded, but as discrete class variables. Weather parameters such as cloud cover (%), wind speed
(mph), humidity (%) and precipitation amount over the previous 4 hours were estimated, and the type of precipitation over the previous four-hour period was
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recorded as a discrete class variable. In an effort to minimize disturbance to toads, the remainder of structural variables were sampled only after toads left the area being analyzed. The percent of overhead canopy cover was estimated at the substrate level and at one meter above the substrate using a convex spherical densiometer (with a 10 part equal size grid and a built-in leveling bubble) to separate the effect of low growing vegetation on the microhabitat where the toad was located from the forest canopy effect resulting from the structure of the macrohabitat. The second sampling unit surveyed concentrated on fine scale or microhabitat structure consisting of two transects (north to south and west to east) centered on the toad location. The line intercept vegetation height or water depth (in cm) were recorded at intervals of 5 cm along each of these transects as well as the intercepting vegetation type recorded as one of 16 vegetation/water classes (sedge, grass, willow, water, soil, rock, duff, lupine, herb, moss, tree, gravel, log, woody vegetation, rushes and sage). The third sampling unit surveyed about each toad location concentrated on coarse scale or macrohabitat structural features. This sampling unit included a visual estimate of the
% cover of each of eight ground cover classes (water, soil, gravel, rock, duff, log, herbaceous vegetation and woody vegetation) occurring within a 1-m2 plot centered on the toad location, and a series of distance measurements (in cm) from the toad location (Figure 1) to the closest of each of several habitat structural features occurring in each of the four quadrants arbitrarily delineated by the compass rose.
These habitat structures are as follows: rock, tree, willow, burrow and water source.
If the distance to any of these habitat structures was greater than 10,000 cm, the distance was recorded as ≥10,000 cm. Two additional variables were also recorded
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for each of the quadrants in relation to the trees measured, and they were the diameter of the tree’s trunk at breast height (1.25 m) and the species of tree recorded as a discrete class. If the tree was shorter than breast height, the diameter was recorded as zero. A complete list of the variables measured for this study is included in Appendix
3.
Data Analysis
Because this study is exploratory rather than confirmatory in nature (Jaeger &
Halliday 1998), a relatively large number of habitat variables were measured to describe as complete a picture of the habitat utilized by B. canorus as possible. Such a large number of variables poses a particular problem for the analysis and especially when compared with the relatively small sample size of 49 locations. However, many of the variables measured for this study are likely to be unimportant to habitat utilization by B. canorus and as such will be effectively eliminated during the ordination analysis. Further, it was determined that the climatic variables such as temperatures, wind speed and cloud cover were not useful as descriptors of the habitat utilized, so they were deleted from the analysis, thereby reducing the number of variables by 7. Finally, the purpose of this study is to develop a descriptive model of the habitat utilized by B. canorus, not confirm an existing habitat model; therefore, with cautious interpretation, the small sample size of this study should be sufficient to develop a habitat model that can be tested in future studies (see McGarigal et al.
2000).
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A second issue with this study, which is a common problem for most ecological studies, is the analytical assumption that the toad habitat locations sampled were selected at random. It is unlikely that a truly random sample can be obtained from a natural population (Reinert 1984), but for this study a truly random sample of habitat locations is even more unlikely owing to the limited sample size and repeated measures on a limited number of individuals (n= 20). Repeated sampling of an individual could make the data interpretation particularly suspect if a single aberrant toad was over-represented in the data set, which is entirely possible because one individual represented 22% of the overall site samples and four individuals combined represented 68% of sites sampled. However, these four individuals may be fairly representative as they represent two males and two females with one of the males and one female being sampled in both meadow and upland sites in approximately equal numbers. Further, the individual locations sampled during the 1997 season did not stand out as remarkable when compared with the habitats toads were observed to occupy in previous seasons, 7 of the sites surveyed were occupied by more than one individual, and 17 locations were occupied by individual toads for extended periods.
Finally, as discussed above, this study is exploratory in nature and as such need not strictly adhere to the underlying mathematical assumptions to elicit useful relationships between sites and habitat variables (Gauch 1982; McGarigal et al.
2000).
The use of discrete class variables in this data set poses something of a problem for most ordination analysis, i.e. PCA (McGarigal et al. 2000). This difficulty is further complicated by the majority of the data set being comprised of
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continuous variables. To analyze all of the variables using a single ordination technique, and to reduce some of the variation in the continuous variables, I converted all the continuous variables into discrete ordinal variables. COVSCN,
COVCN, COVWTR, COVSOL, COVRCK, COVDUF, COVLOG, COVHVG,
COVWVG, COVGVL, which were originally recorded as a percentage, were ordered
0-20 with a 5% interval. The distance/diameter measurements originally recorded as distances in cm from the toad location (Figure 1) to the closest of each of several habitat structural features occurring in each of the four quadrants, including
DSTRCK#, DSTTRE#, DIMTRE#, DSTWLW#, DSTBRW# and DSTWTR#, were averaged for each site. The resulting average values were converted to class variables. DSTWLW# was ordered 0-34 with a 300 cm interval; DSTRCK#,
DSTTRE# and DSTWTR# were ordered 0-29 with a 200cm interval; DIMTRE# was ordered 0-26 with a 10 cm interval; and DSTBRW# was ordered 0-31 with a 15cm interval. NSVGHT## and WEVGHT##, also originally measured as distances in cm, were also averaged for each plot location and the resulting average vegetation height
(avgVGHT) for each plot was ordered 0-21 with a 3cm interval. The resulting discrete ordinal variables for each plot are included in Table 2. To reduce the heterogeneity of the ordinal variables all variables were log-transformed. A
Correspondence Analysis (CA) using MVSP (Kovach 2005) was performed on the resulting transformed structural macrohabitat variables and subsequently on the climatic and structural microhabitat variables to determine the degree of correspondence between variables and sample scores for the two different habitat scales. To reduce the potential influence of unequal class sizes on the overall
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analysis I used the option to down-weight classes with small numbers relative to
other classes, which effectively reduced the effect of the small overwintering class
relative to meadow and upland habitat classes. The Eigenvalues and extracted CA
axes scores for cases and axis loadings for variables were then interpreted both
numerically (following the methods described in McGarigal et al. 2000) and
graphically and then compared with the raw data to build a descriptive model of the
different habitat classes utilized by B. canorus. To test for differences between habitat types and the utilization of those habitats between the sexes, a multivariate analysis of variance (MANOVA) was performed on the CA axes case scores using
® SPSS for Windows, Rel. 16.0.1. 2007 (Chicago: SPSS Inc.). To accommodate the
variance in the microhabitat data set and unequal sample size between groups, it was
also necessary to perform an analysis of variance (ANOVA) on CA axis 1 case scores
® (CA axes are independently derived, McGarigal et al. 2000) also using SPSS for
Windows. To ensure that neither the unequal sample sizes nor possible population
variances affected the conclusions of the MANOVA and/or ANOVA, both Tukey and
Games-Howell post-hoc tests were performed because the Games-Howell test does
not assume that population variances or sample sizes are equal (Garson 2008).
Finally, to test for differences in the pre- and post-grazing vegetation heights, a τ-test
was performed on the vegetation height measures for the paired meadow sites also,
using SPSS.
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RESULTS
Macrohabitat
A Correspondence Analysis of the macrohabitat class and converted ordinal
variables (see Table 2) collected at 49 post-reproductive habitat plots utilized by B.
canorus returned variable axis loadings (Table 3) and axis ordination scores for cases or survey sites (Table 4). The Eigenanalysis (Table 5) reveals that 40.91% (λ1=
0.191) of the variation in the macrohabitat ordination case scores can be explained by
axis 1. Thereafter there is a sharp drop in the amount of variation in the data set
explained by the axis scores with a pronounced inflection in the gradient between
axis 2 (14.96%, λ2= 0.070) and axis 3 (10.92%, λ3= 0.051), and the gradient is much
flatter thereon so subsequent axes do not explain much of the variation and can be
disregarded from further analysis for ease of interpretation.
A scatter plot of macrohabitat axis 1 and 2 CA case scores (Figure 2)
graphically demonstrates quite a good separation of meadow sites on the positive end
of axis 1 from the combined upland and overwintering sites located on the negative
end of axis 1. Axis 2 spreads out the upland and meadow site clusters, but it does not
further separate the habitat classes from one another. The grouping of 18 sites on the
right of the plot or positive side of axis 1 is comprised of the meadow habitat plots.
Twelve of these sites (13, 27, 5, 7, 25, 4, 11, 12, 8, 9, 10 and 6) were located in the
willows along the stream channel within the meadow but well away from breeding
pools. Eight of these habitat plots were occupied by juvenile toads (≤1 year of age)
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and an additional two meadow plots were occupied by subadult individuals (≤2 years of age), which represent the entire immature toad sample measured during this study
(Figure 3). The remaining meadow habitat sites plotting on the positive end of macrohabitat axis 1 are comprised of 4 adult male and 4 adult female toad locations.
The upland and overwintering habitat sites plot on the negative side of axis 1, with the exception of site 19 that has a positive score on axis 1 (0.061), but is still well away from the meadow habitat cluster. Most of the upland sites plot in a tight cluster on the negative ends of axis 1 and axis 2. There are five upland sites that plot away from the major upland cluster on the positive end of axis 2 (52, 18, 16, 17 & 19).
These sites consist of locations where one adult female (TOADID 163, site 52) and one adult male (TOADID 127, sites 16, 17, 18 & 19) were located while being radio tracked. These two individuals were also located at upland sites that plotted on the negative end of axis 2 with the upland habitat cluster, and the female was tracked from meadow habitat to upland habitat, so these sites cannot be considered unusual for the species. The overwintering sites also plot on the negative side of axis 1 with the upland habitat sites, but like the five upland sites discussed above, the overwintering habitat sites plot on the positive end of axis 2.
A comparison of significant (absolute value >0.5= significant, >0.7= highly significant, McGarigal et al. 2000) variable loadings (Table 3) with case scores
(Table 4) for macrohabitat axis 1 and 2 reveals the underlying habitat features that influence the axis scores. Axis 1 is positively correlated with the coverage of woody vegetation (CA variable score= 1.217) and the average distance to rocks (CA variable score= 0.778) and negatively correlated with rock (CA variable score= -0.780), duff
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(CA variable score= -0.739) and log (CA variable score= -0.711) coverages. An area chart of the highly significant 1m2 plot coverages (Figure 3) illustrates that the percentage of woody vegetation on the far right of axis 1, where most of the meadow sites are located, is relatively large ( x = 25.2±6.7%, n= 18) but quickly drops to near
zero for the remainder of axis 1 where the upland and overwintering sites plot ( x =
1.2±0.5%, n= 31). The average distance to rocks is also long (or far away) on the right side of axis 1 where the meadow sites cluster on the scatter plot ( x =
26.60±2.53m, n= 72), but the average distance to rocks drops to less than one meter
on the negative side of axis 1 where the upland and overwintering sites plot ( x =
0.71±0.17 m, n= 31), but the average distance to rocks for the three overwintering sites alone is about a meter and a half longer than for upland sites ( x = 2.07±0.99 m,
n= 3). The percent coverage of rocks in each 1m2 plot arranged on axis 1 shows that
rocks constituted a large percentage on the left side of axis 1 where the upland and
overwintering sites plot ( x = 37.81±4.42%, n= 31) but drops to zero on the positive
side of axis 1 where the meadow sites plot ( x = 0±0%, n= 18). Duff and log
coverages show a similar but not as pronounced trend where the coverages are small
on the negative end of axis 1 where upland and overwintering sites are located (Duff
x = 8.09±2.28%, n= 31 and Log x = 3.58±1.94%, n= 31) but larger than the
coverages that drop to zero or near zero percent on the positive side of axis 1 where
the meadow sites plot (Duff x = 0±0%, n= 18 and Log x = 0.28±0.28%, n= 18); but
the overwintering sites alone have a much greater percentage of duff coverage ( x =
27.0±21.7%, n= 3) than either meadow or upland habitats and zero percent log
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coverage ( x = 0.0±0.0%, n= 3). Macrohabitat axis 2 has a single highly significant
CA variable score for gravel coverage (Figure 5). The percentage of gravel in each
1m2 plot starts out relatively high on the top or positive end of axis 2 ( x =
14.65±3.68%, n= 23) and decreases to zero at a CA case score of about -0.32 ( x =
0.00±0.00%, n=26). The majority of survey sites for meadow and upland habitats plot on the negative end of axis 2 where there is very little gravel present (Figure 2), but all of the overwintering sites ( x = 26.7±16.9%, n= 3), a few upland and a few
meadow sites plotted on the positive or gravel side of axis 2.
It is also instructive to examine the non-significant macrohabitat variable
scores to identify how they may be influencing the axis loadings. Further, it is
instructive to determine which of the measured variables are common to all
macrohabitats occupied by B. canorus. An area chart of the non-significant 1m2 plot coverages (Figure 6) illustrates the percent coverage of the non-significant variables.
Three of the non-significant variables, soil coverage (CA variable score = -0.16), herbaceous vegetation coverage (CA variable score = 0.23) and overstory canopy cover (CA variable score = -0.22), show differences between the habitat types. There is a higher percentage of soil coverage on the negative end of axis 1 where the upland and overwintering sites plot ( x = 13.52±2.47%, n= 31) than on the meadow or
positive end of axis 1 ( x = 5.44±1.13%, n= 18). It should be noted, however, that the
overwintering plots alone have a much smaller percentage of soil more similar to the
meadow sites ( x = 5.0±2.5%, n= 3). The coverage of herbaceous vegetation is
greatest on the positive side of axis 1 where the meadow habitats plot ( x =
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63.72±6.97%, n= 18) and much less on the negative side of axis 1 where the upland
and overwintering sites plot ( x = 25.29±4.01%, n= 31), but the overwintering sites
have a much smaller percentage of herbaceous vegetation ( x = 12.3±3.8%, n= 3)
than upland sites ( x = 26.7±4.4%, n= 28). Overstory canopy cover demonstrates a
similar pattern to soil coverage in that canopy cover is greater on the negative end of
axis 1 where the upland and overwintering habitats plot ( x = 6.61±0.59%, n= 31) and
smaller on the positive end of axis 1 where the meadow habitats plot ( x =
2.17±0.34%, n=18). Water coverage and gravel coverage display very little
difference between upland/overwintering habitats on the negative end of axis 1
(Water x = 2.58±1.60%, n= 31 and Gravel x = 7.93±2.66%, n= 31), and meadow habitats plotting on the positive side of axis 1 (Water x = 0.28±0.28%, n= 18: and
Gravel x = 5.06±3.01%, n= 18). However, overwintering sites have zero percent water coverage ( x = 0.0±0.0%, n= 3), but much greater gravel coverage ( x =
26.7±16.9%, n= 3) than either meadow or upland habitats with which they plot on
axis 1.
The non-significant macrohabitat distance measurements on axis 1 (Figure 7)
show a considerable amount of variation, but only the average distance to willows
and trees show any discernable pattern. The average distance to willows is generally
greater (farther away) on the negative end of axis 1 where the upland and
overwintering sites plot ( x = 47.70±6.13 m, n= 31) than on the meadow or positive
end of axis 1 ( x = 6.25±2.25 m, n= 18). The average distance to trees shows the
opposite pattern where trees are closer to upland and overwintering habitats on the
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negative end of axis 1 ( x = 7.41±0.83 m, n= 31) and on average much farther away from meadow habitats on the positive side of axis 1 ( x = 33.86±3.82 m, n= 18). The average diameter of trees had very little influence (CA variable score= -0.045) on axis 1 (and as such is not included in Figure 7), but shows a very interesting pattern where meadow ( x = 40.84±6.24 m, n= 18) and upland ( x = 49.75±8.70 m, n= 28) habitats are associated with moderate to large diameter trees, while overwintering habitats are associated with very large diameter trees ( x =86.67±36.77 m, n= 3), which suggests that overwintering habitats are associated with mature or old growth lodgepole pine forests. The average distance to burrows and water do not show any significant difference between upland/overwintering habitat plots and meadow habitat plots on axis 1 (Burrows x = 1.95±0.51 m, n= 31 and x = 1.65±0.23 m, n= 18, respectively; Water x = 17.81±2.99 m, n= 31 and x = 13.12±2.47 m, n= 18, respectively). Burrow habitats in particular show relatively little variability in the average distance from toad locations to nearest burrow ( x = 1.84±0.33 m, n= 49) with the minimum distance from all toad locations to burrows being approximately a half meter ( x = 0.62±0.10 m, n= 49), thereby suggesting that burrows are important components of B. canorus habitats. The average distance to water ( x = 16.41±2.08 m, n= 49) shows much more variability than the average distance to burrows (Figures
7 & 8), but the minimum distance from all toad habitats to water ( x = 5.39±0.93 m, n= 49: Figure 8) shows much less variability, and again suggests that an important component of B. canorus habitats is close proximity to a free water source. It should be noted that the distance to water measurements taken during this study include all
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sources of available free water such as ephemeral streams, seeps and springs as well as permanent sources of water, so the mean minimum distance from toad habitat plots to water should not be applied only to permanent water sources that would appear on topographic maps or GIS coverages.
Macrohabitat axis 3, like axis 2, does not further separate upland/overwinter habitats from meadow habitats (Figure 9), but it does demonstrate heterogeneity in two habitat variables among all habitat types. Macrohabitat axis 3 (Table 4) has one highly significant variable, woody vegetation coverage (CA axis 3 variable score
0.96), and one significant variable, log coverage (CA axis 3 variable score 0.66), that score relatively high on the positive end of axis 3 (Figure 10) and relatively low or zero on the negative end of axis 3. Both of these variables were also highly significant on macrohabitat axis 1 (Figure 4), which may help to explain some of the variability among habitat groups on axis 1.
To test for the effect of habitat group (meadow, upland & overwintering) and sex group (male, female & subadult/juvenile) plus the interaction between them
(Design: Intercept + HabitatGroup + SexGroup + HabitatGroup * SexGroup), a
MANOVA was performed on the case scores for macrohabitat Axes 1 and 2 (Table
4). A Box’s M test revealed borderline inhomogeneity in the variance-covariance matrix (M= 37.474, F12,2141.774= 2.674, p= 0.001). However, Box’s test is very sensitive to violations of the assumption of normality, especially when sample sizes are unequal, as is the case with the current analysis, even though MANOVA is fairly robust with respect to the assumptions of homoscedasticity and equality of sample sizes. Therefore, Box’s M is generally tested at the p= 0.001 level (Gill 2001; Garson
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2008) or the level at which the current analysis tested, so the conclusions of the
MANOVA must be interpreted cautiously. The Levene’s test of macrohabitat axes 1 and 2 revealed that the MANOVA assumption of homogeneity of error variances among groups has been met (F6,42= 1.384, p= 0.244 and F6,42= 2.073, p= 0.077 respectively). The MANOVA revealed that there are significant differences between
2 habitat types (Wilk’s λ= 0.391; F4,82= 12.292; p < 0.005; ηp = 0.375), but no difference between habitats occupied by males, females or subadults (Wilk’s λ=
2 0.862; F4,82=1.586; p=0.186; ηp = 0.074), nor is there any significant interaction between habitat and sex (Wilk’s λ = 0.983; F4,82= 0.181; p= 0.948; ηp2= 0.009).
Univariate between-subjects tests (Table 6) showed that habitat type was significantly
2 related to macrohabitat axis 1 (F2= 29.808, p= 0.000, ηp = 0.587) but not to
2 macrohabitat axis 2 (F2= 1.170, p= 0.320, ηp = 0.053). Overall the MANOVA model explained a sizable amount of the variance in macrohabitat axis 1 (adjusted R2=
0.742) but very little of the variance in macrohabitat axis 2 (adjusted R2= -0.039), which supports the interpretation of the CA scatter plots above.
Tukey’s HSD (Table 7) tests show a significant difference between meadow and upland habitats on macrohabitat axis 1 (Mean difference= 1.808±0.157, p =
0.000) and also between meadow and overwintering habitats on macrohabitat axis 1
(Mean difference= 1.673±0.326, p = 0.000); but no significant difference between upland and overwintering habitats (Mean difference= -0.135±0.321, p = 0.907), which confirms the observed groupings suggested by the CA scatter plot. Because the Box’s M test found potential problems with the variance and sample size of the data set, Games-Howell, which does not assume that populations or sample sizes are
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equal, and Bonferroni, which is preferred when the number of groups is small, post hoc tests were also performed (Table 7). These more robust tests were found to demonstrate the same relationships between habitat types as was shown by the
Tukey’s HSD tests, suggesting that the possible violation of the basic assumptions of
MANOVA were not sufficient to alter the basic conclusions of the analysis.
A summation of macrohabitat variable measurements grouped by habitat class rather than axis score can be found in Table 8. This table reveals from a macrohabitat perspective that meadow habitat is characterized by having a large percentage of woody (~25%) and herbaceous vegetation (~60%) coverage with willows being a particularly prominent component of the surrounding vegetation (~5 m). Meadow habitats were found to have very little exposed soil (~5%) or gravel (~5%) and no exposed rock (~0%) or duff (~0%). The overstory canopy coverage of meadow habitats was limited (~2%) owing to meadow habitats being located relatively far
(~30 m) from large diameter (~40 cm) trees. Upland habitats are characterized by having a very small percentage of woody vegetation (~1%) coverage with willows being located well away (~45 m) from the upland habitats sampled, but there was a moderate amount of herbaceous vegetation (~25%) coverage in the sampled upland habitats. There was a greater amount of bare soil (~15%) observed in upland habitats than in either meadow or overwintering habitats, but gravel coverage was small (5%) and in approximately the same percentage range as was found in meadows. Exposed rocks comprised a relatively large percentage (~40%) of upland habitat coverages with the average distance to rocks being less than a meter. Duff constituted a small percentage (~5%) of the cover in upland habitats. Overstory canopy coverage (~6%)
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was greater in upland habitats than in meadows with relatively large diameter trees
(~50 cm) being located relatively close (~5-10 m) to toad upland habitats.
Overwintering habitats like upland habitats are characterized as having a small
percentage of woody vegetation (~2%) coverage and having willows located far away
(~45 m) from the overwintering habitats surveyed. There was a much smaller
percentage of herbaceous vegetation coverage (~12%) at overwintering habitats than
for upland or meadow habitats. The percentage of bare soil coverage (~5%) for
overwintering habitats was similar to that for meadow habitats and much less than
that of upland habitats. The percentage of gravel coverage (~25%) at overwintering
habitats was on average five times greater than that of either meadow or upland B.
canorus habitats surveyed. Exposed rocks constituted a large percentage (~25%) of cover in overwintering habitats but not as great as in upland habitats. The percent coverage of duff (25%) constituted a five times greater percentage of ground cover in overwintering habitats than was found in the upland habitats surveyed. The overstory canopy coverage for overwintering habitats (~7%) was similar to that of upland habitats with the average distance to trees being slightly shorter for overwintering sites (~4 m) than for upland sites. The size of the nearby trees in overwintering habitats (~86 cm), however, was nearly twice the size of the trees located nearest to
upland and meadow habitats. The most consistent macrohabitat variables for the
meadow, upland and overwintering sites surveyed were related to water and rodent
burrows. The percent coverage of free water in all three habitat types was very low
or zero (0.3, 2.9 and 0.0%, respectively). However, toads were located within 10
meters of the nearest free water source in all three habitats (3.76, 6.31 and 6.59 m,
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respectively), and the average distance to water was less than 20 m for all three
habitat types (13.12, 19.21 and 10.07 m, respectively) but upland habitats did show
more variability in the average distance to water than the other two habitat types.
Finally, toads were found less than a meter from a burrow in all three habitat types
(~0.47, ~0.74 and ~0.42 m, respectively), and the average distance to burrows was
less than three meters for all three habitats (~1.5, ~2 and ~2 m, respectively).
Microhabitat
A Correspondence Analysis of the microhabitat class and converted ordinal
variables (see Table 2) collected at 49 post-reproductive habitat plots utilized by B.
canorus returned microhabitat variable axis loadings (Table 9) and microhabitat axis ordination scores for cases or survey sites (Table 10). The Eigenanalysis (Table 11) reveals that 35.00% (λ1= 0.337) of the variation in the microhabitat ordination case
scores can be explained by axis 1. Thereafter there is a sharp drop in the amount of
variation in the data set explained by the axis scores, with a pronounced inflection in
the gradient between axis 2 (15.92%, λ2= 0.153) and axis 3 (10.452%, λ3= 0.101), and
the gradient is much flatter thereon so subsequent axes do not explain much of the
variation and can thus be disregarded from further analysis.
A scatter plot of microhabitat axes 1 and 2 CA case scores (Figure 11)
graphically demonstrates a good separation of most of the meadow sites in a tight
cluster on the positive end of axis 1 from a dispersed cloud of points located on the
negative end of axis 1 that represents upland habitats, overwintering sites and a few
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meadow sites. Axis 2 does little to further separate the habitat types, but axis 2 does spread out the upland, overwinter and associated meadow site cluster. The tight grouping of 14 meadow sites on the right or positive side of axis 1 includes the same
12 meadow habitat plots (27, 13, 25, 4, 7, 10, 11, 5, 9, 8, 6 and 12) located among the willows along the stream channel away from breeding pools that were tightly clustered in the macrohabitat CA. This group includes the entire subadult and juvenile toad sample during this study (Figure 12). This tight cluster also includes two additional habitat plots (29 and 30) representing adult toads basking in the entrances of burrows that were also located along the stream channel. One of the meadow habitat sites (33) not included in the tight cluster above plotted intermediate to the two scatter plot clusters. The remaining three meadow habitat sites (34, 35 and
24) plotted on the negative side of axis 1 with the upland/overwinter habitat cluster.
All but two (53 and 15) of the upland and overwintering habitat sites plot on the negative side of axis 1, but the two upland sites with positive axis 1 scores are still well separated from the tight meadow cluster. The upland habitat sites are widely distributed across axis 2. The overwintering sites also plot on the negative side of axis 1 with the upland habitat sites, but all three overwintering sites plot on the negative end of axis 2.
A comparison of significant (absolute value >0.5= significant, >0.7= highly significant, McGarigal et al. 2000) microhabitat variable loadings (Table 9) with the microhabitat case scores (Table 10) reveals the underlying habitat features that influence the axis scores. Axis 1 is positively correlated with the willow vegetation class frequency (CA variable score= 1.515) and the frequency of the sedge class (CA
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variable score= 1.066) and negatively correlated with duff class (CA variable score= -
0.800), gravel class (CA variable score= -0.696), rock class (CA variable score= -
0.677), and soil class (CA variable score= -0.500) frequencies. An area chart of the
highly significant and significant vegetation class frequencies (Figure 13) illustrates
that the frequency of the willow vegetation class coincides with the tight meadow
habitat cluster on the far right of axis 1 ( x = 13.33±3.5 freq., n= 15), but quickly
drops to near zero for the remainder of axis 1 where the upland and overwintering
sites plot ( x = 0.24±0.16, n= 34). The frequency of the sedge vegetation class is also
much more pronounced on the positive end of axis 1 where the meadow sites are
located ( x = 25.67±3.4 freq., n= 15) but drops to zero for the remainder of axis 1 where the upland and overwintering sites plot ( x = 1.24±0.61, n= 34). The frequency
of duff, gravel and rock classes shows an opposite pattern in which the frequency is
greatest on the negative side of axis 1 where the upland and overwintering sites plot
( x = 3.74±1.04, n= 34; x = 3.68±1.02, n= 34 and x = 12.50±2.06, n= 34,
respectively), but the frequency of all three classes is zero on the meadow or positive
end of axis 1 ( x = 0.00±0.0, n= 15). The frequency of the soil class is sporadically
distributed across the entire length of axis 1, but like duff, gravel and rock classes, the
frequency of exposed soil is greater on the negative side of axis 1 ( x = 3.64±0.75, n=
34) than on the positive side ( x = 0.53±0.35, n= 15). While the average vegetation
height did not have a significant variable score on axis 1 (CA axis 1 variable score=
0.433) it was close to being significant and as such greatly influenced axis 1.
Vegetation height shows a considerable amount of variation along axis 1, but the
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presence of willows on the meadow or positive side of axis 1 appears to have led to average vegetation height being taller ( x = 28.48±2.39, n= 15) than the average vegetation height on the negative or upland and overwintering side of axis 1 where the frequency of soil, gravel, rock and duff classes is greater ( x = 10.12±2.39, n= 34).
There are several peaks in vegetation height occurring in the center of Figure
13 that are not explained by the significant microhabitat variables. However, an examination of the non-significant microhabitat variables in Figure 14 shows that the unexplained peaks in average vegetation height can be explained by the frequency of the lupine vegetation class. Most of the non-significant vegetation classes are represented sporadically on the upland and overwintering habitat end of axis 1 but have very little representation on the meadow or positive end of axis 1. The two best represented non-significant vegetation classes are lupine and herb that have CA variable scores close to being significant on axis 1 (-0.481 and -0.463, respectively), and as such they have an impact on the loading of axis 1. The frequency of the lupine and herb vegetation classes are greater on the negative end of axis 1 ( x = 3.32±1.20, n= 34 and x = 6.71±1.43, n= 34, respectively) than on the positive end ( x = 0.0±0.0, n= 15 and x = 0.80±0.73, n= 15, respectively). The one remaining non-significant microhabitat variable worthy of note is the surface canopy cover, which has no discernable trend in frequency between the negative or upland/overwintering habitat end of axis 1 ( x = 78.97±4.821.20, n= 34) and the positive or meadow end ( x =
63.67±7.41, n= 15).
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Microhabitat axis 2 (Table 10 & Figure 11) does not further separate the tight
meadow cluster from the upland/overwinter cluster, but it does disperse the
upland/overwinter cluster. Axis 2 has two highly significant CA variable scores
which are for lupine (1.512) and duff (-0.705) vegetation classes. These two classes
have their highest frequencies on opposite ends of axis 2 (Figure 15) with the lupine
class frequency greatest on the positive end of axis 2 ( x =7.40±2.36, n= 15) and very
little representation on the negative end ( x = 0.06±0.04, n= 34), and the duff
vegetation class frequency largest on the negative end ( x = 3.50±1.06, n= 34) with very little representation on the positive end of axis 2( x = 0.53±0.26, n= 15). There
are no significant variables loading on microhabitat axis 2, but there are three
vegetation classes that are close to being significant, and they are rock (CA variable
score -0.47), log (-0.46) and herb (0.45). Rock and log have the highest frequencies
on the bottom or negative end of axis 2 ( x = 10.88±2.19, n= 34 and x = 1.24±0.81,
n= 34, respectively) and the lowest frequencies on the top or positive end ( x =
3.67±1.49, n= 15 and x = 0.13±0.09, n= 15, respectively) while the herb vegetation
class has the highest frequency on the positive end of axis 2 ( x = 11.33±2.64, n= 15)
and a much lower frequency on the negative end of axis 2 ( x = 2.06±0.60, n= 34).
To test for the effect of habitat group (meadow, upland & overwintering) and
sex group (male, female & subadult/juvenile) plus the interaction between them
(Design: Intercept + HabitatGroup + SexGroup + HabitatGroup * SexGroup) on
microhabitat utilization, a MANOVA was performed on the case scores for
microhabitat axes 1 and 2 (Table 10). A Box’s M test revealed inhomogeneity in the
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variance-covariance matrix (M= 84.709, F12,2141.774= 6.045, p= 0.000). Further, the
Levene’s test of microhabitat axes 1 and 2 revealed that the MANOVA assumption of
homogeneity of error variances among groups has not been met (F6,42= 8.423, p=
0.000 and F6,42= 5.422, p= 0.000, respectively), so the conclusions of the MANOVA
must be interpreted with caution. The MANOVA did return significant differences
2 between habitat types (Wilk’s λ = 0.591; F4,82= 6.173; p= 0.000; ηp = 0.231) and
between habitats occupied by males, females or subadults (Wilk’s λ= 0.561;
2 F4,82=6.869; p=0.000; ηp = 0.000) but did not reveal any significant interaction
2 between habitat and sex (Wilk’s λ = 0.920; F4,82= 0.873; p= 0.484; ηp = 0.041).
Univariate between-subjects tests (Table 12) showed that habitat type was
2 significantly related to microhabitat axis 1 (F2= 11.875, p= 0.000, ηp = 0.361) but not
2 to microhabitat axis 2 (F2= 2.188, p= 0.125, ηp = 0.094) and that sex group was
2 significantly related to microhabitat axis 1 (F2= 15.115, p= 0.000, ηp = 0.419) but not
2 to microhabitat axis 2 (F2= 0.459, p= 0.635, ηp = 0.021). Overall the MANOVA model explained a sizable amount of the variance in microhabitat axis 1 (adjusted R2=
0.726) but very little of the variance in microhabitat axis 2 (adjusted R2= 0.015),
which supports the interpretation of the CA scatter plots.
Tukey’s HSD (Table 13) tests of habitat classes show a significant difference
between meadow and upland habitats on microhabitat axis 1 (Mean difference=
1.54595±0.160, p= 0.000) and also between meadow and overwintering habitats on
microhabitat axis 1 (Mean difference= 1.84278±0.334, p= 0.000); but no significant
difference between upland and overwintering habitats (Mean difference=
0.29683±0.329, p= 0.641), which confirms the observed groupings suggested by the
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CA scatter plot and concurs with the macrohabitat findings. Tukey’s HSD (Table 14) tests of sex groups show no significant difference between the microhabitat utilization of adult male and adult female toads on microhabitat axis 1 (Mean difference= 0.108±0.176, p= 0.812), but there was a significant difference between the microhabitat utilized by subadults and adult males (Mean difference=
1.933±0.204, p= 0.000) and between the microhabitat utilized by subadults and adult female toads (Mean difference= 2.041±0.2.17, p= 0.000). Because the Box’s M test found potential problems with the variance and sample size of the data set, Games-
Howell, which does not assume that populations or sample sizes are equal, and
Bonferroni, which is preferred when the number of groups is small, post hoc tests were also performed (Tables 13 and 14). These more robust tests were found to demonstrate the same relationships between habitat types and sex classes as was shown by the Tukey’s HSD tests, suggesting that the possible violation of the basic assumptions of MANOVA were not sufficient to alter the basic conclusions of the analysis.
A summation of microhabitat variable measurements grouped by habitat class rather than axis score can be found in Table 15. From the microhabitat perspective illustrated by this table, meadow habitat is characterized by having a high frequency of sedge (~21) and willow (~11) vegetation classes and the tallest average vegetation height (~25 cm) of the three habitat types. Meadows are also notable for their lack of rock, duff, tree, log, woody vegetation (other than willows) and sage classes.
Meadows also had slightly less surface canopy cover than upland or overwintering habitats, but meadows still had ~69% cover, which was only slightly less than the
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other habitats. Upland habitat is characterized as having a moderate frequency of rock (~14) and herbaceous vegetation (~6) classes. Although upland habitat is characterized by a small frequency of water (~1.5), tree (~0.5), log (~1.5) and woody vegetation (~0.4) classes, meadow and overwinter habitat types lack representation in these classes. Upland habitat also has a small frequency of duff vegetation whereas meadow habitat lacks representation in the duff class, but overwintering habitats have a much greater frequency of duff than upland habitats. Grass (~2) and soil (~3.5) class frequencies were also small, but they were larger than the frequency of these classes in either meadow or overwintering habitat types. The only vegetation class not represented in upland habitat was the sage class that was also unrepresented in meadow habitats. Overall, the average vegetation height in upland habitats (~11 cm) was half the height of meadows but three times taller than overwintering habitats.
Upland habitats also had slightly greater surface canopy cover (~77%) than the other habitat types. Overwintering habitats are characterized as having the greatest frequency of duff (~20), gravel (~7) and sage (~4) vegetation classes. The sage class representation in overwintering habitats is particularly notable as the sage class was not observed in the other habitat types. Grass (~2), rock (~3) and herbaceous vegetation (~4.5) classes were all represented in overwintering habitats, but at smaller frequencies than for upland habitats. Overwintering habitats had the most limited representation of vegetation classes as the sedge, willow, water, soil, lupine, moss, log, woody vegetation and rushes class were all unrepresented in overwintering habitats. The average vegetation height (~3 cm) in overwintering habitats was considerably shorter than the vegetation height in the other two habitat types. The
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surface canopy coverage (~73%) was as great as that of the other habitats. The only
two variables that were comparable in all three habitat types were the large
percentage of surface canopy coverage and a small frequency of grass in each habitat
type.
A summation of microhabitat variable measurements grouped by sex class
rather than axis score can be found in Table 16. From the microhabitat perspective
illustrated by this table, the habitat of adult male and female B. canorus can be characterized by a rocky substrate with a moderate frequency of herbaceous vegetation that is generally less than 13 cm in height and a surface canopy cover of
75-80%. Most of the measured vegetation classes remaining are represented in the adult habitats surveyed in small frequencies. Subadult (combined juvenile and subadult classes) microhabitat, on the other hand, can be characterized by a high frequency of sedges and willows with a relatively tall average vegetation height (~30 cm), but a somewhat smaller surface canopy cover of about 57%. Grass is occasionally found in subadult microhabitats and bare soil rarely occurs, but the remaining measured vegetation classes are unrepresented in subadult microhabitat.
Cattle Grazing
Finally, eleven of the meadow sites (4, 5, 6, 7, 8, 9, 10, 12, 13, 25 and 27) that were located along the stream channel in or near low growing willows were surveyed between 23 and 27 August 1997. At some point over the following 14 days cattle grazed the entire meadow. The site identification flags had been left in place for later
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mapping, so these sites were resurveyed on 13 September 1997, thereby providing an opportunistic comparison of vegetation heights. Vegetation heights before cattle grazing were significantly taller than vegetation heights after cattle had grazed the area ( x = 27.70±0.66 cm and x = 17.69±0.66 cm, respectively: t22= -0.576, p= 0.005, n= 11). A more important observation is that toads could no longer be located along the stream channel after cattle grazing had occurred, but both subadult and adult B. canorus could be found in dense willow thickets elsewhere in the meadow or in other parts of the meadow that were less intensively grazed by cattle.
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CONCLUSIONS
Meadow habitats utilized by B. canorus have significantly different structural
features from upland and overwintering terrestrial habitats at both the macrohabitat
and microhabitat scales. The MANOVA of macrohabitat correspondence analysis
axis case scores found that meadow habitats are significantly different from upland
and overwintering habitats but that upland habitats are not significantly different from
overwintering habitats. Overall, the macrohabitat variable loadings indicate that B.
canorus meadow habitat plots can be characterized by minimal rock and gravel presence and a relatively large percentage of both herbaceous and woody vegetation.
More specifically, the loadings suggest that meadow plots are located relatively far from trees (~33 m) and rocks (~25 m), but relatively close to willows (~6 m).
Conversely, the variable loadings indicate that upland habitat can be characterized by a rocky substrate with herbaceous vegetation rather than woody vegetation and that gravel, duff and downed logs are occasionally found in this habitat type. The variable loadings further indicate that upland plots are located relatively close to trees (~8 m) and rocks (<1 m) but relatively far from willows (~48 m). Overwintering habitats can be characterized by a rocky-gravel substrate with a relatively high percentage of duff coverage and relatively sparse herbaceous vegetation with very little woody vegetation. Variable loadings further indicate that overwintering habitats are located relatively far from willow stands (~45 m) but very close (~4 m) to relatively large
(~86 cm diameter) trees, which suggests that overwintering habitats are located in stands of old growth trees. Despite the apparent differences, all three habitat types
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utilized by B. canorus were less than a meter from a burrow and less than seven meters from an available free water source of some type, which includes ephemeral streams, seeps and springs.
Similarly, the MANOVA of microhabitat correspondence analysis axis case scores found that meadow habitats are significantly different from upland and overwintering habitats but that upland habitats are not significantly different from overwintering habitats. Further, the MANOVA found that the microhabitat utilized by subadult B. canorus was significantly different from microhabitats utilized by adult male and adult female toads, but that there was no significant difference between the microhabitats utilized by adult male and adult female B. canorus.
Microhabitat variable loadings indicate that the microhabitat utilized in meadows can be characterized by a relatively large frequency of sedges (sedge class vegetation height x = 20.98±0.43 cm, n= 430) and willows (willow class vegetation height x =
44.13±0.96 cm, n= 208) and thus a relatively tall average vegetation height of
approximately 25 cm. Conversely, meadow habitats have a very low or nonexistent
frequency of duff, soil, gravel, rock, lupine and sage classes. The microhabitat of
upland sites has the highest frequency of soil, rocks, lupines (lupine class vegetation
height x = 34.82±2.28 cm, n= 113) and herbaceous vegetation (herbaceous
vegetation class height x = 27.31±2.00 cm, n= 235) of any of the three habitat types.
The higher frequency of bare soil, gravel and rock is probably responsible for upland habitats having an intermediate average vegetation height of approximately 11 cm, as the mean height of lupines and herbaceous vegetation measured during this study is considerably taller (above and see appendix 3). The frequency of sedge, willow, duff
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and gravel in upland microhabitats was small but all classes had at least some
representation in upland habitats. The microhabitat of overwintering sites has the
highest frequency of duff and gravel classes of any of the habitat types, but
overwintering microhabitats measured during this study lack any representation of
sedge, willow, soil and lupine classes, and thus has the shortest average vegetation
height of approximately 3 cm.
The microhabitats occupied by adult male and adult female B. canorus are characterized by a rocky substrate with a moderate frequency of herbaceous vegetation that is approximately 12 cm in height, and has a surface canopy cover of approximately 80%. Adult B. canorus microhabitats surveyed during this study were found to contain at least some representation of all of the measured vegetation classes, suggesting that adult toads can occupy a variety of microhabitats within the macrohabitats described above. The microhabitats occupied by subadult (juvenile and subadult classes combined) B. canorus are characterized by a high frequency of sedges and willows with a relatively tall average vegetation height of approximately
30 cm, but a some what smaller surface canopy cover than that of adults at about
57%. Grass is occasionally found in subadult microhabitats and bare soil rarely occurs, but the remaining measured vegetation classes are unrepresented in subadult microhabitat, which suggests that subadult B. canorus have very restrictive microhabitat requirements.
Overall, the meadow habitats utilized by post reproductive B. canorus during
this study generally matched the description of preferred habitat for this species given
in the literature; but the upland habitats utilized during this study, which this study
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suggests are more commonly used by adult toads than meadow habitats, are different
from the rather vague (and rare) upland habitat descriptions in the literature. For
example, the literature states that upland habitats are often associated with steeply
sloping mountain sides where the vegetation is unusually rich or in dense willow
thickets concentrated along ephemeral streams, seepages or near hibernacula
(Mullally 1953; Mullally & Cunningham 1956; Karlstrom 1962; Kagarise Sherman
1980; Morton 1981; Kagarise Sherman & Morton 1984); whereas in the current study
willows were not an important component of upland habitat plots but rocks were an
important component of the habitat, and the overwintering burrows were located a
considerable distance away from the upland habitats (see Chapter 2). However, most
of the upland plots did occur in or near patches of dense herbaceous vegetation, on
steep slopes well above the meadow habitats utilized for breeding and subadult
rearing, and I have observed B. canorus terrestrial stages occupying upland habitats with dense willow thickets in close association with ephemeral water sources during previous tracking studies in the same meadow complex. Although I do not suggest that the previous upland habitat descriptions are incorrect (and considering this study concentrated on only one study population, it would be inappropriate for me to do so), I do, however, suggest that B. canorus is capable of occupying more diverse upland habitats than previously suggested and that upland habitats are the dominant habitat type utilized by post-reproductive foraging B. canorus.
The overwintering habitats utilized by B. canorus are much more difficult to characterize due to the small sample size, which makes it difficult to distinguish between anomalous individual behavior and actual diversity in the structural features
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of hibernacula; but since these are the only hibernacula known to have been utilized
by B. canorus, I believe it is important to report the limited data available.
Overwintering habitat plots generally clustered with upland habitats where the structural habitat features were significantly different from meadow sites and, as such, can be characterized as having a rocky-gravel substrate, herbaceous vegetation and close proximity to trees. However, the overwintering sites are different from upland sites in that the vegetation tends to be shorter, the trees are closer and larger than for upland sites, and all three overwintering sites were abandoned rodent burrows, so they were obviously closer to burrows. The separation of overwintering sites from both meadow and upland habitats is not surprising because spatially overwintering sites are located between the meadow and upland habitats along the lodgepole pine forest-sagebrush edge (see Chapter 2) where the soil is much drier and herbaceous vegetation is sparse. Such relatively dry habitat may provide better protection from freezing winter temperatures than would be provided by a wet meadow or upland habitats with moist soils (Karlstrom 1962). Further, the overwintering burrows are located on low gradient slopes that were 1-2 meters higher in elevation than the meadows proper, which should reduce the risk of rain or snowmelt entering the burrow and subsequent freezing during early snow melt when environmental conditions are highly variable.
The hibernacula suggested in the literature are closely associated with upslope willow thickets and rocky substrate (Kagarise Sherman 1980; Morton 1981); whereas the overwintering sites in this study were located in rocky substrate along the lodgepole pine forest edge relatively close to meadows but far away from willows
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and relatively far away from upland habitats. Again, this sample size is small, so I can only conclude that B. canorus is capable of utilizing more diverse overwintering habitats than previously known. I also think further study on the effect of sex and breeding condition on overwintering location choice could help explain some of the apparent variation in overwintering sites with males and reproductively active females tending to overwinter closer to breeding pools (see Sinsch 1991, 1992).
One important habitat descriptor given by Karlstrom (1962), namely that B. canorus is rarely found more than 90 meters from a permanent water source, bears further examination. In the current study meadow and upland habitat plots were never found to be more than approximately 7 meters from a water source, which suggests B. canorus may be more closely associated with water than previously understood; but in this study ephemeral streams and seepages were considered water sources if free water was available to the toads at the time of observation, and upland habitats tended to be associated with ephemeral water sources rather than the more permanent waters usually associated with meadows. However, from a management perspective it may be easer to define toad habitat based on permanent water sources, which usually appear on US Geological Survey maps and thus GIS coverages, than to define the habitat based on ephemeral water sources that are more difficult to locate at the landscape level. Given the spatial separation between upland and meadow habitats discussed in Chapter 2, it may be more appropriate to use the 500 meter adult toad dispersal distance from breeding pools to upland habitat or Morton’s (1981) more conservative 750 meter distance from the closest meadow breeding site to incorporate the core habitat needs of B. canorus than Karlstrom’s (1962) 90 meter
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distance estimate that would severely underestimate the core habitat needs of this
species as most of the upland habitats utilized are much farther than 90 m from
breeding pools (pers. obs. and see Chapter 2).
The protection of the upland and meadow foraging habitat from degradation is
at least as important, if not more important, than protecting breeding habitat utilized
by B. canorus because amphibian population viability is often closely tied to the survivorship of adult individuals in foraging habitats (Semlitsch 2000; Biek et al.
2002; Vonesh & De la Cruz 2002; Semlitsch & Bodie 2003; Semlitsch & Rothermel
2003; Storfer 2003). However, current US Forest Service management practices have
thus far focused on the protection, via fencing, of B. canorus breeding pools and the meadow habitats immediately surrounding them for a limited period of time, thereby leaving much of the meadow foraging habitat and the entire upland foraging habitat subject to uncontrolled grazing. It is clear from the significant decrease in vegetation height of the 11 grazed meadow foraging sites (from approximately 28 cm to approximately 17 cm, and USFS management plans allow vegetation to be further reduced to a stubble height of 8 cm, USDA 2003), coupled with the sudden disappearance of toads from the area after grazing had occurred for approximately one week, that cattle have the ability to greatly alter foraging habitat structure over very short periods of time. How the alteration of terrestrial habitat by cattle impacts the survivorship of terrestrial stages is unknown at this time, but considering the fact that the toads vacated previously occupied habitat after cattle grazing had occurred during this study, coupled with the previous observations of toad mortality resulting directly from grazing activities in the same meadow complex (Martin 1991b; 1997,
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pers. obs.), it is reasonable to deduce that cattle grazing is having a negative effect on
terrestrial stage survivorship.
Of greater concern is the current management practice of fencing B. canorus
breeding pools in meadows (see USDA 2003) that may actually increase the impact
of cattle grazing on B. canorus terrestrial foraging habitats. Cattle in the Sierra tend to prefer grazing in the wet meadows and riparian areas where the vegetation is more lush, leaving much of the area contained within a given grazing allotment largely unused for grazing (Kie & Boroski 1996; Calhoun & Hunter 2003), so the fencing of a portion of the meadow without reducing cattle numbers simply increases the impact of grazing on nearby habitats with lush vegetation. In cases where much of the meadow has been fenced for grazing protection, such as Milk Ranch Meadow and
Lower Gardner Meadow located within the Highland Lakes grazing allotment, cattle shifted their grazing preferences to the nearby upland habitats that are occupied by toads (pers. obs.); and while upland habitats may support lush vegetation, they are also typically much smaller in area than meadow habitats and located on much steeper terrain, which is more susceptible to overgrazing and erosional damage
(Ratliff 1982), and will thus suffer greater impact than the same number of cattle would cause in a meadow. This scenario is a classic example of well intended management practices failing to protect species due to the absence of adequate knowledge of the specialized needs of amphibians (Beebee 1996; Sztatecsny &
Schabetsberger 2005) and underscores the need for continuing further research into the terrestrial habitat needs of amphibians and reevaluating the impact of current management practices on amphibian populations and the actual habitats that they
306
utilize. The current study provides a foundation for the kinds of terrestrial habitat data required for land managers to more effectively protect amphibian habitat (both breeding and terrestrial foraging), and thus maintain viable populations of Bufo canorus.
307
LITERATURE CITED
Albright, R., L. Hanson, P. Kaunert, C. Madden, A. Palmer, R. Ruediger, D. Van
Keuren, R. Wetzel, L. Conway, and J. Frazier. 1994. Highland Lakes Term
Permit and Allotment Management Plan. Pages 1-76. Stanislaus National
Forest, Sonora, CA.
Alford, R. A., and S. J. Richards. 1999. Global amphibian declines: A problem in
applied ecology. Annual Review of Ecology and Systematics 30:133-165.
Beebee, T. J. C. 1996. Ecology and Conservation of Amphibians. Chapman & Hall,
London.
Beebee, T. J. C., and R. A. Griffiths. 2005. The amphibian decline crisis: A
watershed for conservation biology? Biological Conservation 125:271-285.
Biek, R., W. C. Funk, B. A. Maxell, and L. S. Mills. 2002. What is missing in
amphibian decline research: Insights from ecological sensitivity analysis?
Conservation Biology 16:728-734.
Blaustein, A. R., and D. B. Wake. 1990. Declining amphibian populations: A global
phenomenon? Trends in Ecology & Evolution 5:203-204.
Blaustein, A. R., and D. B. Wake. 1995. The puzzle of declining amphibian
populations. Scientific American 1995:52-57.
Bradford, D. F., and M. S. Gordon. 1992. Aquatic Amphibians in the Sierra Nevada:
Current Status and Potential Effects of Acidic Deposition on Populations.
California Air Resources Board, Contract No. A932-139., Sacramento, CA.
308
Brown, C. 2002. Population and Habitat Monitoring for the Yosemite Toad: Sierra
Nevada Framework Project. Pages 1-29 +Attachments. USFS, Sacramento,
CA.
Calhoun, A. J. K., and J. Hunter, Malcolm L. 2003. Managing ecosystems for
amphibian conservation. Pages 228-241 in R. D. Semlitsch, editor.
Amphibian Conservation. Smithsonian Books, Washington, D.C.
Camp, C. L. 1916. Description of Bufo canorus, a new toad from the Yosemite
National Park. University of California Publications in Zoology 17:11-14.
Dodd, C. K., and B. S. Cade. 1998. Movement patterns and the conservation of
amphibians breeding in small, temporary wetlands. Conservation Biology
12:331-339.
Drost, C. A., and G. M. Fellers. 1996. Collapse of a regional frog fauna in the
Yosemite area of the California Sierra Nevada, USA. Conservation Biology
10:414-425.
Dueser, R. D., and J. H. H. Shugart. 1978. Microhabitats in a forest-floor small
mammal fauna. Ecology 59:89-98.
Garson, G. D. 2008. Statnotes: Topics in Multivariate Analysis. North Carolina
State University.
Gauch, H. G. 1982. Multivariate Analysis in Community Ecology. Cambridge
University Press, Cambridge.
Gill, J. 2001. Generalized Linear Models: A Unified Approach. Sage Publications,
Thousand Oaks, CA.
309
Grinnell, J., and C. L. Camp. 1917. A distributional list of the amphibians and
reptiles of California. University of California Publications in Zoology
17:127-208.
Grinnell, J., and T. I. Storer 1924. Animal Life in the Yosemite. University of
California Press, Berkeley, California.
Jaeger, R. G., and T. R. Halliday. 1998. On confirmatory versus exploratory
research. Herpetologica 54:S64-S66.
James, F. C. 1971. Ordinations of habitat relationships among breeding birds.
Wilson Bulletin 83:215-236.
Jennings, M. R. 1996. Status of Amphibians. Pages 921-944 in Sierra Nevada
Ecosystem Project: Final Report to Congress. University of California,
Centers for Water and Wildland Resources, Davis, CA.
Jennings, M. R., and M. P. Hayes. 1994. Amphibian and Reptile Species of Special
Concern in California. Pages iv-255. California Department of Fish & Game,
Inland Fisheries Division, Rancho Cordova, CA.
Kagarise Sherman, C. 1980. A Comparison of the Natural History and Mating
System of two Anurans: Yosemite Toads (Bufo canorus) and Black Toads
(Bufo exsul). University of Michigan, Ann Arbor.
Kagarise Sherman, C., and M. L. Morton. 1984. The toad that stays on its toes.
Natural History 93:72-78.
Kagarise Sherman, C., and M. L. Morton. 1993. Population declines of Yosemite
toads in the eastern Sierra Nevada of California. Journal of Herpetology
27:186-198.
310
Karlstrom, E. L. 1962. The toad genus Bufo in the Sierra Nevada of California.
University of California Publications in Zoology 62:1-104.
Kie, J. G., and B. B. Boroski. 1996. Cattle distribution, habitats, and diets in the
Sierra Nevada of California. Journal of Range Management 49:482-488.
Korner, C. 2002. Mountain biodiversity, its causes and function: an overview. Pages
3-20 in C. Korner, and E. M. Spehn, editors. Mountain Biodiversity: A
Global Assessment. The Parthenon Publishing Group, Boca Raton, FL.
Kovach, W. L. 2005. MVSP - A Multivariate Statistical Package for Windows.
Kovach Computing Services, Pentraeth, Wales, U.K.
Lind, A. J., R. Grasso, S. Parks, P. A. Stine, B. Allen-Diaz, S. McIlroy, K. Tate, L.
Roche, W. FROST, and N. K. McDougald. 2006 [abstract]. Determining the
Effects of Livestock Grazing on Yosemite Toads (Bufo canorus) and their
Habitat: An Adaptive Management Study in D. Bradford, editor. Declining
Amphibian Task Force (DAPTF)California-Nevada Working Group Meeting
2006, Humboldt State University, Arcata, CA.
Martin, D. L. 1991a [abstract]. Population census of a species of special concern:
The Yosemite toad (Bufo canorus). Page 31. Fourth Biennial Conference of
Research in California's National Parks. Cooperative National Parks
Resources Studies Unit, University of California, Davis, California.
Martin, D. L. 1991b [abstract]. The dramatic decline of a species of special concern:
The Yosemite Toad (Bufo canorus). Page 78. Joint Annual Meeting of the
Herpetologists' League and the Society for the Study of Amphibians and
Reptiles, Penn State University, University Park, Pennsylvania.
311
Martin, D. L. 1997 [abstract]. Habitat utilization and population dynamics of the
Yosemite toad, Bufo canorus, as it relates to management decisions in the
Sierra Nevada of California. Page 205. Joint Annual Meeting of the
American Society of Ichthyologists and Herpetologists, Herpetologists'
League, Society for the Study of Amphibians and Reptiles, American
Fisheries Society, American Elasmobranch Society and the Gilbert
Ichthyological Society, University of Washington, Seattle, Washington.
Martin, D. L., M. R. Jennings, H. H. Welsh, and D. Dondero 1992. Anuran Survey
Protocol for the Sierra Nevada of California. Canorus Ltd. Press, Sacramento,
CA.
McGarigal, K., S. Cushman, and S. Stafford 2000. Multivariate Statistics for Wildlife
and Ecology Research. Springer, New York, NY.
Menke, J. W., C. Davis, and P. Beesley. 1996. Rangeland Assessment. Pages 901-
972 in Sierra Nevada Ecosystem Project: Final Report to Congress.
University of California, Centers for Water and Wildland Resources, Davis,
CA.
Morrison, C., and J. M. Hero. 2003. Geographic variation in life-history
characteristics of amphibians: a review. Journal of Animal Ecology 72:270-
279.
Morrison, M. L., B. G. Marcot, and R. W. Mannan 1992. Wildlife-Habitat
Relationships: Concepts and Applications. The University of Wisconsin
Press, Madison, Wisconsin.
312
Morton, M. L. 1981. Seasonal changes in total body lipid and liver weight in the
Yosemite toad. Copeia 1981:234-238.
Mullally, D. P., Pvt. 1953. Observations on the ecology of the toad Bufo canorus.
Copeia 1953:182-183.
Mullally, D. P., Pvt., and J. D. Cunningham. 1956. Aspects of the thermal ecology of
the Yosemite toad. Herpetologica 12:57-67.
Oliver, J. A. 1955. The Natural History of North American Amphibians and Reptiles.
D. van Nostrand Co., Inc., Princeton, New Jersey.
Pechmann, J. H. K., D. E. Scott, R. D. Semlitsch, J. P. Caldwell, L. J. Vitt, and J. W.
Gibbons. 1991. Declining amphibian populations - the problem of separating
human impacts from natural fluctuations. Science 253:892-895.
Ratliff, R. D. 1982. A Meadow Site Classification for the Sierra Nevada, California.
Page 16. Pacific Southwest Research Station, Forest Service, U.S. Dept. of
Agriculture, Berkeley, CA.
Reagan, D. P. 1974. Habitat selection in the three-toed box turtle, Terrapene
carolina triunguis. Copeia 1974:512-527.
Reinert, H. K. 1984. Habitat separation between sympatric snake populations.
Ecology 65:478-486.
Schabetsberger, R., R. Jehle, A. Maletzky, J. Pesta, and M. Sztatecsny. 2004.
Delineation of terrestrial reserves for amphibians: post-breeding migrations of
Italian crested newts (Triturus c. carnifex) at high altitude. Biological
Conservation 117:95-104.
313
Schwarzkopf, L., and R. A. Alford. 1996. Desiccation and shelter-site use in a
tropical amphibian: comparing toads with physical models. Functional
Ecology 10:193-200.
Semlitsch, R. D. 1981. Effects of implanted tantalum-182 wire tags on the mole
salamander Ambystoma talpoideum. Copeia 1981:735-737.
Semlitsch, R. D. 2000. Principles for management of aquatic-breeding amphibians.
Journal of Wildlife Management 64:615-631.
Semlitsch, R. D. 2002. Critical elements for biologically based recovery plans of
aquatic-breeding amphibians. Conservation Biology 16:619-629.
Semlitsch, R. D., editor. 2003a. Amphibian Conservation. Smithsonian Books,
Washington, D.C.
Semlitsch, R. D. 2003b. Conservation of pond-breeding amphibians. Pages 8-23 in
R. D. Semlitsch, editor. Amphibian Conservation. Smithsonian Books,
Washington, D. C.
Semlitsch, R. D., and J. R. Bodie. 2003. Biological criteria for buffer zones around
wetlands and riparian habitats for amphibians and reptiles. Conservation
Biology 17:1219-1228.
Semlitsch, R. D., and B. B. Rothermel. 2003. A foundation for conservation and
management of amphibians. Pages 242-259 in R. D. Semlitsch, editor.
Amphibian Conservation. Smithsonian Books, Washington, D.C.
Sinsch, U. 1990. Migration and orientation in anuran amphibians. Ethology Ecology
& Evolution 2:65-79.
314
Sinsch, U. 1991. The orientation behavior of amphibians. Herpetological Journal
1:541-544.
Sinsch, U. 1992. Sex-biased site fidelity and orientation behavior in reproductive
natterjack toads (Bufo calamita). Ethology Ecology & Evolution 4:15-32.
Stebbins, R. C. 1951. Amphibians of Western North America. University of
California Press, Berkeley, California.
Stebbins, R. C. 1966. A Field Guide to Western Reptiles and Amphibians. Houghton
Mufflin Company, Boston, Mass.
Stebbins, R. C., and N. W. Cohen 1995. A Natural History of Amphibians.
Princeton University Press, Princeton, NJ.
Storer, T. I., and R. L. Usinger 1963. Sierra Nevada Natural History: An Illustrated
Handbook. University of California Press, Berkeley, CA.
Storfer, A. 2003. Amphibian declines: future directions. Diversity and Distributions
9:151-163.
Sztatecsny, M., and R. Schabetsberger. 2005. Into thin air: Vertical migration, body
condition, and quality of terrestrial habitats of alpine common toads, Bufo
bufo. Canadian Journal of Zoology 83:788-796.
Travis, J. 1994. Calibrating our expectations in studying amphibian populations.
Herpetologica 50:104-108.
USDA, F. S. 2003. Sierra Nevada Forest Plan Amendment (SNFPA): Management
Review and Recommendations -- Part 1: Assessing the Need For Change;
Impacts to Grazing; Impacts from Standards and Guidelines for Sensitive
Species. Pages 61-75, Pacific Southwest Region.
315
Vonesh, J. R., and O. De la Cruz. 2002. Complex life cycles and density dependence:
assessing the contribution of egg mortality to amphibian declines. Oecologia
133:325-333.
Wake, D. B., and H. J. Morowitz. 1990. Declining amphibian populations: A global
phenomenon? Page 11. National Research Council Board on Biology, Irvine,
CA.
Wilbur, H. M. 1980. Complex life cycles. Annual Review of Ecology and
Systematics 11:67-93.
Williams, S. 2002. 50 CFR Part 17: 12-month finding for a petition to list the
Yosemite toad. Federal Register 67:75834-75843.
316
TABLES t Microhabitat Microhabitat y y y y sis y toads internal bod internal toads ) for Anal for °C 3-Overwintering 3-Overwintering ( Identification Onl Identification Onl p 3-Med, 4-High, 5-Wet 4-High, 3-Med, 2-Female, 3-Subadult, 4-Juvenile 3-Subadult, 2-Female, 2-Basking, 3-Active, 4-PostGrazing 3-Active, 2-Basking, Toad classified Toad Activity 1-Burrow, as Sex of individual classified as 1-Male, as 1-Male, classified Sex of individual Sub. Sub. classified Moisture as 1-Dry, 2-Low, Habitat classified as 1-Meadow, 2-Upland, 2-Upland, 1-Meadow, as classified Habitat Incorporated Not CLSSEX so into Incorporated a Variable r r erature Tem p Number Identification Onl g Climatic andstructural variables used habitat.to toad quantify AGEAge Toad Estimated TIME Plot Habitat in Toad with of Encounter Time AM/PM HH:MM DATE Toad with Plotin Encounter Habitat Date of MM/DD/YYYY SITEID Fla Site PLOTID Plot Identification Numbe TOADID Identification Toad Numbe CLSHBT Habitat Classification CLSSEX Classification Sex TMPAIRCLSSUB Temperature Air Substrate Class Temp (°C) 10 substrate cm above Sub. classified 1-Soil,as 2-Water, 3-Rock Microhabita CLSACT Toad Activity Classification CLSSMO Substrate MoistureClass TMPSUB Substrate Temperature Temp (°C) of withinsubstrate 5 cm of toad COVCLD Cover Cloud head over ofclouds (%) Coverage TMPCLO Cloacal Tem SPDWND Speed Wind (mph) wind speed of estimate Subjective TMPBRW Temperature Burrow burrow of center at (°C) Temp Mnemonic Variable Method Sampling Scale Habitat FLAGNUM Number Identification Site Only Identification Table 1. Continued nextpage.
317
Macrohabitat Macrohabitat Macrohabitat ) % (
y quadrant centered 2 quadrant on toad location toad on Same as as COVWTRSame as COVWTRSame Macrohabitat Macrohabitat within each quadrant each within ective estimate of relative humidit of relative estimate ective j Distance (cm)Distance to nearest withintree each Sub Coverage (%) within within 1-m (%) Coverage Distance (cm) to nearest rock (?30 cm width) (?30 width) cm rock nearest to (cm) Distance r r y Cover COVWTRas Same Macrohabitat y etation Cove etation g itation Amountitation station weather auto. 4 hrfrom PPT Cum. p COVCNCanopy (overstory) High Meter height 1m at (%) closure canopy Macrohabitat Denisometer COVSOL Cover Soil COVWTRas Same Macrohabitat AMTPPT Preci COVDUF Cover Duff as COVWTR Same Macrohabitat COVSCNCanopy Surface level toad at (%) closure canopy Denisometer Microhabitat COVGVLDSTTRE#CLSTRE# Gravel Cover Tree to Distance Classification Type Tree 3-Whitebark 2-Hemlock, 1-Lodgepole, Macrohabitat as Same COVWTR Macrohabitat COVLOGCOVHVG Ve Herb. Cover Log COVWTRas Same Macrohabitat PRCHUM Humidit COVRCK Rock Cove DIMTRE# High Breast Tree Diam. groundabove m ~1.25 at tree of (cm) Diam. Macrohabitat COVWTR Water Cover COVWVG Wood DSTRCK# Rock to Distance Mnemonic Variable Method Sampling Scale Habitat DSTBRW# to Burrow Distance as DSTTRE Same Macrohabitat DSTWLW# Willow to Distance DSTTREas Same Macrohabitat Table 1. (continued). 1. Table Continued nextpage.
318
Microhabitat Microhabitat 15-Rushes, 16-Sage 15-Rushes, the the transect N-S 1m 5cm every 12-Gravel, 13-Log, 14-WoodyVeg, 14-WoodyVeg, 13-Log, 12-Gravel, Veg Classified as 1-Sedge, 2-Grass, 2-Grass, as 1-Sedge, Classified Veg 8-Lupine, 9-Herb, 10-Moss, 11-Tree, 3-Willow, 4-Water, 5-Soil, 6-Rock, 7-Duff, 7-Duff, 6-Rock, 5-Soil, 4-Water, 3-Willow, Veg Height or Water Depth (cm) intersecting intersecting (cm) Depth Water or Height Veg Depth North-SouthVegetation Height orWater MnemonicNSVGH## Variable Method Sampling Scale Habitat DSTWTR# SourceWater Nearest to Distance DSTTREas Same Macrohabitat WEVGH## West-East Vegetation Height or Water Depth or Water Height WEVGH## Vegetation West-East NSVGH##as Same Microhabitat NSVCLS## Class or Water Vegetation North-South Table (continued). 1. WEVCLS## or West-East Vegetation Class Water as Same NSVCLS## Microhabitat
319
Surface Surface Canopy Moisture Substrate Class Substrate Date Time Activity Class Habitat Converted discrete ordinal variables used in the correspondance analysis. 456 157 158 15 1849 15 118 SubAdult 15 119 Meadow Juvenile 15 116 8/27/1997 Juvenile Meadow PM 120 3:45 SubAdult 8/27/1997 Meadow 121 Meadow PM 3:59 8/27/1997 Juvenile 3 8/27/1997 PM 4:02 Juvenile Meadow PM 3:50 3 8/27/1997 Meadow 3 PM 4:05 8/27/1997 1 3 PM 4:08 0 3 1 3 1 5 1 4 1 5 10 5 8 4 14 3 8 16 16 101112 1513 1514 15 12215 15 123 Juvenile16 22 124 Juvenile Meadow17 114 22 8/27/1997 Juvenile Meadow18 129 21 PM 4:10 8/27/1997 Juvenile Meadow19 21 106 PM 4:11 8/27/1997 Meadow Female20 21 3 127 PM 4:12 8/27/199721 21 127 Upland 3 Male PM 4:13 22 127 21 3 7/26/1997 Male23 PM 22 Male 10:20 127 1 3 Upland 22 Male 1 127 Upland 1 Upland 8/27/1997 Male 22 163 1 Upland 8/23/1997 8/25/1997 163 1 1:46 Male 5 PM AM Female 10:30 Upland 8/12/1997 163 7:23 5 PM 1 Female PM 11:24 7/26/1997 Upland 1 Upland 1 5 PM 11:00 Female Upland 7/28/1997 12 1 1 5 8/24/1997 AM 8:38 7/28/1997 Upland 14 3 2 PM 12:55 1 3:17 1 8/23/1997 8 PM 3 4 3 8 PM 4:30 1 2 1 19 1 3 1 3 1 4 3 1 5 20 1 17 3 20 20 2 0 1 3 20 20 20 18 Plot IDPlot ID Site ID Toad Sex Class Table 2. Continued next page.
320
Surface Surface Canopy Moisture Substrate Class Substrate Substrate Date Time Activity Class Habitat 242527 2129 1530 15 10631 24 10632 15 Male 10633 21 Male 106 Meadow34 21 Male 163 8/13/1997 Meadow35 21 Male 128 AM 9:01 8/23/1997 Meadow Female36 21 125 PM 4:20 8/24/1997 Meadow37 Meadow Male 21 163 2 PM 3:39 8/26/1997 Female38 7/23/1997 23 163 2 PM 5:45 PM 10:05 Female39 Upland 23 Upland 163 2 Female40 Meadow 7/26/1997 16 4 1 1 7/25/1997 46 PM Female 10:44 41 7/23/1997 Meadow 21 PM 1 9:48 16 PM42 7:07 7/24/1997 Meadow 21 Female 1 21 3 AM43 7:36 7/24/1997 3 21 127 1 1 Male 4 3 Winter PM44 9:35 21 127 Male 5 245 21 Male 10/23/95 127 1 Winter 4 3 3 PM 11:10 21 Male 127 Winter 12/10/1995 1 2 4 4 Upland PM 22 Male 3:01 127 1 6 1 10/23/95 Upland 7/24/1997 Male 127 14 1 2 PM 12:30 PM 10:30 1 Upland 7/16/1997 Male 106 1 20 19 PM 12:23 4 Upland 7/25/1997 Male 1 3 1 Upland 3 AM 8:45 7/24/1997 Male 3 18 AM 10:36 1 Upland 1 7/4/1997 3 10 1 Upland AM 7/23/1997 11:50 2 1 3 10 PM 1 4:50 7/23/1997 1 2 PM 6 9:42 1 1 1 1 1 3 20 3 1 4 20 1 3 20 19 3 1 17 2 20 2 17 3 10 20 12 Plot IDPlot ID Site ID Toad Class Sex Table 2. (continued). Table Continued next page.
321
Surface Canopy Moisture Substrate Class Substrate Substrate Date Time Activity Class Habitat 464748 2249 2250 22 12951 22 106 Female52 22 12953 Male 22 129 Upland Female54 21 129 7/26/1997 Female Upland 22 106 AM Upland 2:44 Female 7/25/1997 163 22 Upland 7/25/1997 AM 8:10 1 Male 163 AM Upland 8:10 7/24/1997 Female 106 PM 9:54 7/24/1997 1 Female Upland 1 AM Upland 8:12 1 7/24/1997 3 Male Upland 7/25/1997 AM 8:12 1 AM 8:01 7/25/1997 1 1 Upland PM 1:30 1 1 3 7/23/1997 2 1 PM 6:33 2 1 1 1 2 1 20 1 1 3 20 20 1 3 13 2 20 4 20 20 3 8 16 Plot IDPlot ID Site ID Toad Sex Class Table 2. (continued). Continued next page.
322
Gravel Gravel Coverage Woody Woody Coverage Vegetation Vegetation Herb. Herb. Coverage Vegetation Log Log Coverage Duff Duff Coverage Rock Rock Coverage Soil Soil Coverage Water Water Coverage High High Meter Meter Canopy 210151 2 0 0 4201001135 0 5402000142 6200000128 7401000163 8201000118 0145 9201000 10008 0 0 0 1030100010100 8 0 0 0 3 11401000182 12400000146 13401000190 14701840 15 2 2 6 16 2 3 1 17 4 0 1 121860041111 5 0 0 719080200 720606630 021506621 22303822 023 0 2 0 16 0 7 14 2 14 4 1 3 1 0 0 6 0 6 1 1 1 1 0 0 0 1 8 6 6 0 1 Plot ID Table 2. (continued). Table Continued next page.
323
Gravel Coverage Woody Woody Coverage Vegetation Vegetation Herb. Coverage Vegetation Vegetation Log Coverage Duff Coverage Rock Rock Coverage Soil Soil Coverage Water Water Coverage High High Meter Meter Canopy 50007 0 0 7 010 0 1 5150 1 24103000 2170 0 25202000171 5 0 1 1 27201000190 1 3 29201000 30110000 1 1 31605910 0 3230511103 33103000170 4 012 0 0 34101000190 0 35103000170 1 0 3680114102 9 0 0 37702020 3860131402 39200100190 40462210 0 0 0 4190111107 8 0 0 42601530110 4380106102 44509335 45403612 Plot ID Table 2. (continued). Continued next page.
324
Gravel Coverage Woody Woody Coverage Vegetation Herb. Coverage Vegetation Log Coverage Duff Coverage Rock Rock Coverage Soil Soil Coverage Water Water Coverage High High Meter Meter Canopy 60917 0 1 5 0 0 1 0 0 1 0 0 31211 46502911 0 01810 47 01810 48 7 0 9 4970 125070 125170 52204010 053603611101 054 6 10 6 11 0 11 1 1 1 0 4 0 2 1 2 0 1 0 0 15 0 0 0 Plot ID Table 2. (continued). Continued next page.
325
Class Grass Class Sedge Avg. Avg. Height Vegetation Vegetation Avg. Avg. Distance to Water Avg. Avg. Distance Distance to Burrow Avg. Avg. Distance Distance to Willow Avg. Avg. of Tree Diameter Diameter Avg. Avg. to Tree Distance Avg. Avg. to Rock to Distance Distance 114139331 45121841173 6 1 7745411629382 7 1910270 8 1099 170 15 9 18 5 16 1 1 3 1 14 1 4 3 7 3 9 7 13 28 14 18 10 22 0 0 314158411 101112 101391642195 1014 1015 17161523420200 17 1171523420200 18 0181413430000 11914134190200 32011134814100 2 321148497203 4 12215411213201 023 3 1 4 4 1 31 7 7 4 6 13 6 13 7 16 11 22 10 5 12 6 11 34 2 23 4 1 10 2 2 0 0 1 1 16 0 11 0 0 Plot ID Table 2. (continued). Continued next page.
326
Class Grass Class Sedge Avg. Avg. Height Vegetation Vegetation Avg. Avg. Distance to Water Avg. Avg. Distance Distance to Burrowto Avg. Avg. Distance Distance to Willow Avg. Avg. of Tree Diameter Diameter Avg. Avg. to Tree to Distance Avg. Avg. to Rock to Distance Distance 242527111751856390 2529 3 18 8 112021100 3031 22 13321 17 2633 1 712266204 34 18 835 420107100 26 24 5 326402100 36 22 103733 4 19 5 1 342426801 1 326226400 3811 10 26 0 13906 3271151600 15 327329500 401 8 15 04115 920213000 14 0 54215 12 4 94313 13 74413 5 2 12 2451656826190 7 16 8 23 15 1 8 11 14 4 6 22 10 21 9 11 5 13 16 42 14 1 19 0 4 0 0 6 3 0 3 6 4 0 25 2 0 0 0 1 0 8 0 Plot ID Table 2. (continued). Table Continued next page.
327
Class Grass Class Sedge Avg. Avg. Height Vegetation Vegetation Avg. Avg. Distance Distance to Water Avg. Avg. Distance Distance to Burrow Avg. Avg. Distance to Willow Avg. of Tree Diameter Diameter Avg. Avg. to Tree Distance Distance Avg. Avg. to Rock to Distance Distance 46033794203 470413467120 480413467110 495003582312130 5103582312130 0525325715113432 54045239311 3 3 4 10 8 6 17 9 10 12 14 3 1 0 17 0 11 Plot ID Table 2. (continued). Table Continued next page.
328
Log Log Class Class Gravel Gravel Tree Tree Class Moss Moss Class Veg. Veg. Class Herb. Herb. Class Lupine Duff Class Rock Rock Class Soil Soil Class Class Water Class Willow Willow 440000000000 570100000000 6240000000000 720000000000 8200000000000 9150000000000 4 1210 0 0 10280200000000 71160000000000 21200 0 013201100 12190000000000 0 01420 1300000000000 140 154 160002210300160 170002210300160 18000750000327 19033050040000 20007135030380 21006184040002 22001956020007 230271321070010 Plot ID Table 2. (continued). Table Continued next page.
329
Log Class Class Gravel Tree Class Moss Class Veg. Veg. Class Herb. Herb. Class Lupine Duff Duff Class Rock Rock Class Soil Soil Class Class Water Water Class Willow 240010000000230 2500000000000 2700000003000 29330000010000 30420000000000 31007217140000 32006275100030 0 0 33005000111000 34007000290000 0 0 3500600630000 36000324050080 0 0370000110900150 1 0241700 38000629000000 0 317241600 390 40091002620030 410 42000304350000 430010202220000 44007227000042 4500113760041 Plot ID Table 2. (continued). Continued nextpage.
330
Log Class Class Gravel Gravel Tree Tree Class Moss Moss Class Veg. Veg. Class Herb. Herb. Class Lupine Duff Class Rock Rock Class Soil Soil Class Class Water Water Class Willow 6 1410 4 1 1 0 0 0 0 0 1 313401400 0 0 0 0 0 3 33600 0 0 0 3 0 0 43600 0460 0 0 0 0 0 11800 0470 0 0 0 0 0 1 03720 480 0 03720 490 500 510 0 013001600 520010015500100 53406003160080 540 Plot ID Table 2. (continued). Continued next page.
331
Sage Sage Class Class Rushes Rushes Veg. Class Woody Woody 4000 5000 6000 7000 8000 9000 101112 013 014 015 0 016 0 017 0 0 0 18 0 0 0 19 0 0 0 20 0 0 0 21 0 0 0 22 0 3 0 23 0 0 0 0 2 0 0 0 0 5 0 0 0 0 0 0 0 Plot ID Table 2. (continued). Continued next page.
332
Sage Sage Class Class Rushes Rushes Veg. Class Woody Woody 242527 029 030 031 0 032 0 033 0 0 0 34 0 0 0 350190 0 0 0 36 0 0 0 37 0 0 38 0 2 0 39 5 0 0 40 0 0 41 0 0 0 42 0 043 0 0 1 44 0 0 3 45 0 6 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Plot ID Table 2. (continued). Continued next page.
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Sage Class Class Rushes Rushes Veg. Class Woody Woody 464748 049 050 051 0 052 0 053 0 0 0 540100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Plot ID Table 2. (continued).
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0.234 -0.148 -0.233 0.067 0.031 -0.225 -0.012 -0.107 -0.165 -0.194 -0.121 0.059 e 1.217 0.032 0.969 -0.23 e g g e -0.78 -0.104 0.22 -0.185 e g g etation Covera etation etation Covera etation g g Soil Covera Soil . Diameter Treeof -0.045 -0.11 -0.106 0.013 Log CoverageLog -0.711 -0.047 0.664 1.819 Ve Duff CoverageDuff -0.739 -0.078 0.249 -0.13 Rock CoveraRock g Water CoverageWater 0.031 0.379 0.05 -0.217 Gravel CoverageGravel -0.148 1.354 -0.06 -0.045 y Meter High Canopy High Meter -0.216 -0.102 0.093 -0.059 Avg. Distance to Treeto Distance Avg. 0.321 0.008 -0.037 0.064 Avg. Distance to Rockto Distance Avg. Av 0.778 0.089 -0.148 0.145 Avg. Distanceto Water Avg. Distance to Willowto Distance Avg. Burrowto Distance Avg. -0.412 0.054 0.183 0.034 -0.007 -0.113 -0.002 -0.064 Macrohabitat Macrohabitat variable loadings returned from a correspondence analysis for the Macrohabitat VariablesMacrohabitat 1 Axis 2 Axis 3 Axis 4 Axis Herb. Ve Wood
Table 3. of variables. descriptions detailed 1 for Table See axes. four first
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Table 4. Macrohabitat ordination scores for cases (meadow, upland and overwinter) on the first four axes. Habitat Plot ID Sex Class Axis 1 Axis 2 Axis 3 Axis 4 Class 4 Meadow SubAdult 1.17 0.186 0.595 1.104 5 Meadow Juvenile 1.082 0.533 -0.619 0.103 6 Meadow Juvenile 1.906 -0.36 1.129 -0.145 7 Meadow SubAdult 1.152 -0.638 -0.076 -0.149 8 Meadow Juvenile 1.598 -0.595 0.786 -0.222 9 Meadow Juvenile 1.617 1.679 2.067 -0.814 10 Meadow Juvenile 1.746 -0.545 1.226 -0.252 11 Meadow Juvenile 1.294 -0.729 -0.616 0.013 12 Meadow Juvenile 1.557 -0.554 0.585 -0.195 13 Meadow Juvenile 0.771 -0.634 -1.771 0.352 14 Upland Female -0.79 -0.809 -0.149 -0.829 15 Upland Male -0.609 -0.251 0.542 -1.05 16 Upland Male -1.136 2.306 0.304 -0.777 17 Upland Male -1.136 2.306 0.304 -0.777 18 Upland Male -1.298 1.669 1.756 4.497 19 Upland Male 0.061 2.929 0.439 -0.796 20 Upland Male -0.494 0.028 1.184 -1.109 21 Upland Female -0.702 -0.311 -0.066 0.573 22 Upland Female -0.86 -0.921 0.44 1.32 23 Upland Female -0.408 -0.156 -0.491 -0.363 24 Meadow Male 0.803 1.755 -1.83 0.425 25 Meadow Male 1.164 -0.687 -1.136 0.318 27 Meadow Male 0.953 -0.729 -1.912 0.524 29 Meadow Male 1.999 -0.69 1.675 -0.316 30 Meadow Female 2.231 -0.258 1.864 -0.266 31 Upland Male -0.518 -0.27 -0.546 -0.626 32 Upland Female -0.665 -0.252 -0.475 -0.767 33 Meadow Female 0.709 0.301 -1.818 0.559 34 Meadow Female 0.784 -0.524 -1.824 0.443 35 Meadow Female 0.573 0.108 -1.747 0.303 36 Winter Female -0.727 0.707 0.507 -1.033 37 Winter Male -0.207 1.885 -1.008 -0.314 38 Winter Male -0.795 0.124 0.835 -1.087 Continued next page.
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Table 4. (continued). Habitat Plot ID Sex Class Axis 1 Axis 2 Axis 3 Axis 4 Class 39 Upland Male -0.316 -0.119 -1.306 0.069 40 Upland Male -0.36 -0.384 -0.657 -0.663 41 Upland Male -0.72 -0.845 -0.133 -0.747 42 Upland Male -0.711 -0.803 -0.197 -0.593 43 Upland Male -0.527 -0.887 0.394 -0.794 44 Upland Male -1.118 -0.822 1.002 2.468 45 Upland Male -0.66 -0.769 0.078 1.619 46 Upland Female -0.934 -0.105 0.11 0.516 47 Upland Male -0.889 -1.152 -0.131 -0.819 48 Upland Female -0.889 -1.152 -0.131 -0.819 49 Upland Female -0.933 -1.034 0.138 0.334 50 Upland Female -1.014 -0.759 0.234 -1.301 51 Upland Male -1.014 -0.759 0.234 -1.301 52 Upland Female -0.086 1.562 -1.267 -0.145 53 Upland Female -0.327 -0.619 0.339 0.607 54 Upland Male -0.632 -1.257 -0.018 0.736
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Axis 1 Axis 2 Axis 3 Axis4 Axis5 Axis 6 Axis 7 Axis 8 Axis 9 Axis 10 Eigenanalysis of Eigenanalysis the first ten macrohabitat axis scores extracted from the analysis. correspondence Percentage 40.913 14.964 10.915 10.15 6.523 4.567 3.245 2.944 2.465 1.914 Eigenvalues 0.191 0.07 0.051 0.047 0.03 0.021 0.015 0.014 0.011 0.009
Table 5. PercentageCum. 40.913 55.877 66.792 76.942 83.465 88.031 91.276 94.22 96.685 98.599
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b Power Power Observed Noncent. Noncent. Parameter Eta Eta Partial Partial Squared FSig. Mean Mean Square 66 6.659 24.003 0.778 0.000 0.703 0.648 0.774 0.091 144.016 4.220 1.000 0.247 df a c Sum of of Sum Squares Type III Variable Dependent MacroAxis 1MacroAxis 39.957 MacroAxis 2 1MacroAxis 4.666 2MacroAxis 0.030 1MacroAxis 0.486 2 1MacroAxis 16.540 1 1MacroAxis 0.030 2.588 2 2 0.107MacroAxis 0.486 1.777 8.270 0.746 1 2 0.439MacroAxis 0.321 29.808 2 0.511 2MacroAxis 1.294 0.000 0.084 0.003 1 2 1.170MacroAxis 0.888 0.454 0.010 0.587 2 0.320 2 3.202MacroAxis 11.653 0.161 0.107 0.051 1 2 0.145 46.436MacroAxis 0.042 42 0.053 0.439 59.615 2 0.865 0.151MacroAxis 0.227 51.668 0.277 42 0.132 1 0.860 0.062 0.205MacroAxis 51.325 1.106 49 0.007 2.341 1.000 0.815 2 0.099 MacroAxis 51.609 49 0.007 6.405 51.102 48 0.010 0.290 0.243 48 0.303 0.581 0.411 0.071 0.072 0.080 Univariate Univariate between-subjects effects tests. Error Total Source Intercept Sex Group Sex Group Sex Habitat Group Habitat Corrected Total Habitat Group * Group Habitat Corrected Model Corrected a. R Squared = .774 (Adjusted R Squared = 0.742) = Squared R (Adjusted = .774 R Squared a. b. -0.039) Computed= using alpha = Squared 0.05 R (Adjusted = .091 R Squared c. Table 6.
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Difference 95% Confidence Interval for Interval Confidence for 95% Lower Bound UpperBound Sig. Std. Std. Error (I-J) Mean Mean Difference Difference Group Upland 0.135 0.321 1.000Upland -0.666 0.135 0.936 0.197 0.790 -0.795 1.066 Upland 0.135 0.321 0.907 -0.645 0.916 Overwinter 1.673*Overwinter 0.326 -0.135 0.000 0.321 0.880 0.907Overwinter 1.673* -0.916Overwinter 2.465 0.326 -0.135 0.000 0.645 0.321 0.859 1.000Overwinter 1.673* -0.936Overwinter 2.486 0.249 -0.135 0.001 0.666 0.197 0.911 0.790 -1.066 2.434 0.795 (J) Habitat Habitat (J) Group Upland Meadow -1.808* 0.157 0.000Upland -2.189 Meadow -1.808* -1.427 0.157 0.000Upland -2.199 Meadow -1.808* -1.417 0.178 0.000 -2.252 -1.364 Overwinter Meadow 1.673* 0.326 0.000Overwinter -2.486 Meadow 1.673* -0.859 0.249 0.001 -2.434 -0.911 (I) Habitat Overwinter Meadow -1.673* 0.326 0.000 -2.465 -0.880 Bonferroni Meadow Upland 1.808* 0.157 0.000 1.417 2.199 Games-Howell Meadow Upland -1.808* 0.178 0.000 1.364 2.252 Post-hoc multiple for macrohabitatcomparisons axis 1. Dependent Variable MacroAxis 1MacroAxis HSD Tukey Meadow Upland 1.808* 0.157 0.000 1.427 2.189 Based on observed means. The error term is Mean Square (Error) = 1.106. (Error) Square is Mean term error The means. observed on Based The mean* difference significant is 0.05 at the level. Table 7.
340
Table 8. Summation of macrohabitat variable measurements grouped by habitat class rather than by axis score. Variables are given a relative measure discription (none, small, medium, large and etc.) for each habitat type as well as the mean and standard error for each combination of iable and habitat type. Meadow Upland Overwinter Variables n = 18 n = 28 n = 3 Med-Small Med-Large Med-Large Canopy Cover 2.2 ± 0.3% 6.6 ± 0.7% 7.0 ± 0.6% Very Small Small None Water Coverage 0.3 ± 27.7% 2.9 ± 1.8% 0.0 ± 0.0% Small Med-Small Small Soil Coverage 5.4 ± 1.1% 14.4 ± 2.7% 5.0 ± 2.5% None Large Medium-Large Rock Coverage** 0.0 ± 0.0% 38.9 ± 4.5% 27.3 ± 21.6% None Small Medium-Large Duff Coverage** 0.0 ± 0.0% 6.1 ± 1.1% 27.0 ± 21.7% Very Small Small None Log Coverage** 0.3 ± 27.0% 4.0 ± 2.1% 0.0 ± 0.0% Very Large Medium Med-Small Herb. Veg. Coverage 63.7 ± 7.0% 26.7 ± 4.4% 12.3 ± 3.8% Woody Veg. Large Small Small Coverage** 25.2 ± 6.7% 1.1 ± 0.6% 1.7 ± 0.9% Small Small Large Gravel Coverage** 5.1 ± 3.0% 5.9 ± 2.2% 26.7 ± 16.9% Long Very Short Short Avg. Dist. To Rock** 26.60 ± 2.53 m 0.57 ± 0.15 m 2.07 ± 0.99 m Med-Long Short Short Avg. Dst. To Tree 33.86 ± 3.82 m 7.77 ± 0.71 m 4.16 ± 0.66 m Large Large Very Large Avg. Dim. Of Tree 40.84 ± 6.24 cm 49.75 ± 8.70 cm 86.67 ± 36.77 cm Short Long Long Avg. Dst. To Willows 6.25 ± 2.25 m 48.04 ± 3.94 m 45.34 ± 10.67 m Very Short Very Short Very Short Min. Dst. To Burrow 0.47 ± 0.10 m 0.74 ± 0.16 m 0.42 ± 0.11 m Short Short Short Avg. Dst. To Burrow 1.65 ± 0.23 m 1.91 ± 0.55 m 2.38 ± 0.61 m Very Short Very Short Very Short Min. Dst. To Water 3.76 ± 1.30 m 6.31 ± 1.36 m 6.59 ± 2.79 m Short Short Short Avg. Dst. To Water 13.12 ± 2.47 m 19.21 ± 3.22 m 10.07 ± 2.28 m * Significant at the 0.05 level. ** Significant at the 0.001 level.
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Activity 0.201 0.057 -0.012 -0.045 Soil ClassSoil -0.5 0.27 0.155 0.1 Log ClassLog -0.466 -0.464 -0.168 0.325 Tree ClassTree -0.059 -0.107 -0.064 -0.065 Duff ClassDuff -0.8 -0.705 0.128 0.037 Sage ClassSage -0.09 -0.184 -0.071 -0.06 Rock ClassRock -0.677 -0.47 -0.472 -0.231 Grass ClassGrass 0.046 0.293 -0.15 1.242 Moss ClassMoss 0.193 -0.061 -0.045 -0.217 Sedge ClassSedge 1.066 -0.217 0.251 -0.181 Water ClassWater -0.105 0.258 -0.07 -0.225 Gravel ClassGravel -0.696 -0.299 1.317 0.125 Lupine ClassLupine -0.481 1.512 0.185 -0.567 Rushes ClassRushes -0.165 0.366 -0.347 0.442 Willow ClassWillow 1.515 -0.167 -0.046 0.174 Substrate ClassSubstrate -0.066 -0.086 0.056 -0.064 Surface Canopy 0.002 -0.096 -0.059 -0.029 Substrate MoistureSubstrate 0.241 -0.028 0.012 -0.088 Avg. Vegetation Height Height Vegetation Avg. 0.433 0.211 -0.082 -0.081 Microhabitat VariablesMicrohabitat 1 Axis 2 Axis 3 Axis 4 Axis Woody Vegetation Class Vegetation Woody -0.35 0.094 0.153 -0.184 Microhabitat loadings variable a returned from forcorrespondence analysis the Herbaceous Vegetation Class Vegetation Herbaceous -0.463 0.454 -0.123 0.153
Table 9. of variables. descriptions detailed 1 for Table See axes. four first
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Table 10. Microhabitat ordination scores for cases (meadow, upland and overwinter) on the first four axes. Habitat Plot ID Sex Class Axis 1 Axis 2 Axis 3 Axis 4 Class 4 Meadow SubAdult 1.452 -0.029 0.077 1.598 5 Meadow Juvenile 1.692 -0.186 0.327 0.165 6 Meadow Juvenile 1.895 -0.385 0.166 -0.412 7 Meadow SubAdult 1.519 -0.189 0.3 0.319 8 Meadow Juvenile 1.878 -0.387 0.192 -0.456 9 Meadow Juvenile 1.876 -0.427 0.257 -0.506 10 Meadow Juvenile 1.608 -0.139 0.134 0.409 11 Meadow Juvenile 1.618 -0.234 0.207 0.402 12 Meadow Juvenile 1.944 -0.392 0.243 -0.477 13 Meadow Juvenile 1.317 -0.198 0.445 -0.302 14 Upland Female -0.482 -0.022 -1.294 2.181 15 Upland Male 0.15 -0.467 -0.829 -0.416 16 Upland Male -0.839 -0.982 1.261 -0.422 17 Upland Male -0.868 -1.002 1.294 -0.406 18 Upland Male -0.828 -1.698 0.416 0.052 19 Upland Male -0.228 0.16 -0.916 -0.741 20 Upland Male -0.965 -0.744 1.011 -0.16 21 Upland Female -0.641 -0.321 -0.937 1.007 22 Upland Female -0.754 -0.487 -0.404 0.637 23 Upland Female -0.706 1.019 -0.015 -1.102 24 Meadow Male -0.032 -0.411 3.632 -0.138 25 Meadow Male 1.442 -0.371 0.634 -1.22 27 Meadow Male 1.225 -0.356 0.479 -1.119 29 Meadow Male 1.561 0.008 -0.261 1.445 30 Meadow Female 1.74 -0.2 -0.422 0.112 31 Upland Male -0.852 -0.15 -0.739 0.305 32 Upland Female -1.07 -0.761 0.572 -0.845 33 Meadow Female 0.535 0.42 0.318 -0.404 34 Meadow Female -0.316 1.137 -0.444 1.215 35 Meadow Female -0.243 2.06 -0.293 1.53 36 Winter Female -1.153 -1.344 1.582 0.035 37 Winter Male -0.475 -0.569 2.109 1.589 38 Winter Male -0.782 -1.741 -0.522 -0.557 Continued next page.
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Table 10. (continued). Habitat Plot ID Sex Class Axis 1 Axis 2 Axis 3 Axis 4 Class 39 Upland Male -0.259 2.349 -0.256 -1.512 40 Upland Male -0.303 2.066 1.064 -0.819 41 Upland Male -0.771 0.738 -0.762 -0.96 42 Upland Male -0.312 1.556 -0.743 -0.938 43 Upland Male -0.534 2.166 0.102 -1.553 44 Upland Male -1.126 -1.477 0.627 -0.213 45 Upland Male -0.08 0.561 1.303 -0.943 46 Upland Female -0.864 -0.404 0.243 1.101 47 Upland Male -0.405 -0.74 -1.179 -1.014 48 Upland Female -0.54 -0.673 -1.25 -0.937 49 Upland Female -0.404 -0.054 -1.321 2.189 50 Upland Female -0.265 -1.542 -1.114 -1.318 51 Upland Male -0.265 -1.542 -1.114 -1.318 52 Upland Female -0.724 1.282 1.769 1.746 53 Upland Female 0.113 1.024 1.514 0.658 54 Upland Male -0.269 0.091 -1.245 0.498
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0.337 0.153 0.101 0.084 0.079 0.06 0.048 0.038 0.035 0.019 Axis 1Axis 2 Axis 3 Axis 4 Axis 5 Axis 6 Axis 7 Axis 8 Axis 9 Axis 10 Axis Eigenanalysis of the first ten microhabitat axis scores extracted from the correspondence analysis. correspondence the from extracted axis scores microhabitat ten first the of Eigenanalysis Percentage 35.001 15.921 10.447 8.676 8.162 6.211 4.973 3.916 3.588 1.947 Eigenvalues
Table 11. PercentageCum. 35.001 50.922 61.369 70.046 78.208 84.419 89.393 93.308 96.896 98.843
345
b Power Power Observed Observed Noncent. Noncent. Parameter Eta Eta Partial Partial Squared FSig. Mean Mean Square 66 6.464 22.238 1.103 0.000 1.118 0.368 0.761 0.138 133.426 6.710 1.000 0.390 df a b 48.033 48 Sum of Squares Type III Variable Dependent Dependent MicroAxis 2MicroAxis 1MicroAxis 6.617 2MicroAxis 0.007 1MicroAxis 3.666 2MicroAxis 1 6.904 1MicroAxis 1 4.315 0.007 2MicroAxis 2 8.787 3.666 0.024 1MicroAxis 2 0.906 3.452 0.879 3.718 2MicroAxis 2 0.530 11.875 2.158 0.061 1MicroAxis 0.001 2 0.000 1.424 4.393 2.188 2MicroAxis 12.208 2 0.081 15.115 0.453 0.125 0.361 1MicroAxis 41.416 2 0.000 0.024 42 0.265 0.459 2MicroAxis 51.545 0.094 3.718 42 0.712 0.635 0.419 23.751 0.912 0.291 1MicroAxis 48.357 0.053 49 0.409 0.722 0.986 MicroAxis 50.991 2 0.021 4.376 49 0.470 0.492 30.230 0.992 0.042 48 0.033 0.919 0.422 0.999 1.825 1.444 0.120 0.197 0.164 MicroAxis 1MicroAxis 38.783 Univariate between-subjects between-subjects Univariate effects tests. Error Total Source Intercept Sex Group Sex Group Habitat Group Habitat Corrected Total Corrected Habitat Group * Group Habitat Corrected Model a. R Squared = .761 (Adjusted R Squared = 0.726) = Squared R (Adjusted = .761 R Squared a. 0.05 = alpha using Computed 0.015) b. = Squared R (Adjusted = .138 R Squared c. Table 12. 12. Table
346
Difference 95% Interval for Confidence Lower BoundLower Bound Upper Sig. Std. Error Std. (I-J) 0.297 0.329 0.6410.297 -0.502 0.329 1.096 1.0000.297 -0.523 0.206 1.117 0.447 -0.703 1.297 1.546*1.843* 0.160 0.334 0.000-0.297 0.0001.546* 1.1561.843* 0.329 1.032 0.160 0.641 0.334 1.936 0.000 2.654 -1.096-0.297 0.0001.546* 1.1461.843* 0.329 0.502 1.010 0.229 1.000 0.295 1.946 0.000 2.675 -1.117-0.297 0.000 0.971 0.206 0.523 1.016 0.447 2.121 2.670 -1.297 0.703 Mean Mean -1.546*-1.843* 0.160 0.000 0.334-1.546* 0.000 -1.936-1.843* 0.160 -2.654 -1.156 0.000 0.334 -1.032 -1.546* 0.000 -1.946-1.843* 0.229 -2.675 -1.146 0.000 0.295 -1.010 0.000 -2.121 -2.670 -0.971 -1.016 Difference Group Upland Upland Upland Overwinter Overwinter Overwinter Overwinter Overwinter Overwinter (J) Habitat Group Upland Meadow Upland Meadow Upland Meadow Overwinter Meadow Overwinter Meadow Overwinter Meadow (I) Habitat Bonferroni Meadow Upland Games-Howell Meadow Upland Post-hoc multiple comparisons for microhabitat axis 1 for habitat class. for 1 habitat axis microhabitat for comparisons multiple Post-hoc Dependent Variable Dependent
Table 13. 13. Table 1MicroAxis HSD Tukey Meadow Upland = 0.986. (Error) Square is Mean term error The means. observed on Based 0.05 level. the at significant differenceis mean The *
347
Difference 95% Confidence Interval for for Interval Confidence 95% Lower Bound Upper Bound Sig. Std. Error Std. (I-J) 0.108 0.176 0.8120.108 -0.318 0.176 0.534 1.0000.108 -0.330 0.233 0.546 0.889 -0.464 0.680 -0.1081.933* 0.1762.041* 0.812 0.204 0.217-0.108 0.000 -0.534 0.0001.933* 0.176 1.4372.041* 0.318 1.513 0.204 1.000 0.217 2.429 -0.108 0.000 -0.546 2.569 0.0001.933* 0.233 1.4232.041* 0.330 1.499 0.168 0.889 0.188 2.442 0.000 -0.680 2.583 0.000 1.517 0.464 1.563 2.348 2.518 Mean Mean -1.933*-2.041* 0.204 0.217 0.000-1.933* 0.000 -2.429-2.041* 0.204 -2.569 -1.437 0.000 0.217 -1.513 -1.933* 0.000 -2.442-2.041* 0.168 -2.583 -1.423 0.188 0.000 -1.499 0.000 -2.348 -2.518 -1.517 -1.563 Difference Difference Female Female Female Group Subadult Subadult Subadult Subadult Subadult Subadult (J) Habitat Group Female Male Female Male Female Male Subadult Male Subadult Male Subadult Male (I) Habitat Bonferroni Male Female Games-Howell Male Female Post-hoc multiple comparisons for microhabitat axis 1 sex groups. sex 1 axis microhabitat for comparisons multiple Post-hoc Dependent Variable Dependent
Table 14. 1MicroAxis Tukey HSD Male Female = 0.986. (Error) Square Mean is term error The means. observed on Based 0.05 level. the at significant difference is mean The *
348
Table 15. Summation of microhabitat variable measurements grouped by habitat class rather than by axis score. Variables are given a relative measure description (none, few, moderate, many and etc.) for each habitat type as well as the mean and standard error for each combination of variable and habitat type. Meadow Upland Overwinter Variables n = 18 n = 28 n = 3 Surface Canopy LargeLarLarge ge 69.44 ± 6.89 77.50 ± 5.50 73.33 ± 17.64 Avg. Vegetation Tall Medium Short Height 25.19 ± 2.73 11.01 ± 2.85 3.27 ± 0.82 Sedge Class** Many Few None 21.89 ± 3.49 1.18 ± 0.69 0.00 ± 0.00 Few Few Few Grass Class 1.67 ± 0.68 2.04 ± 0.88 2.00 ± 1.15 Willow Class** Moderate Very Few None 11.11 ± 3.17 0.29 ± 0.20 0.00 ± 0.00 Water Class NoneVery Few None 0.00 ± 0.00 1.57 ± 1.21 0.00 ± 0.00 Soil Class* Few Few None 1.72 ± 0.73 3.61 ± 0.85 0.00 ± 0.00 Rock Class* None Moderate Few 0.00 ± 0.00 14.86 ± 2.26 3.00 ± 1.73 None Few Many Duff Class** 0.00 ± 0.00 2.39 ± 0.47 20.00 ± 5.20 Lupine Class Very Few Few None 0.33 ± 0.33 3.82 ± 1.43 0.00 ± 0.00 Herbaceous Few Moderate Few Vegetation Class 2.44 ± 1.68 6.50 ± 1.49 4.67 ± 2.60 Moss Class Very Few Very Few None 0.22 ± 0.17 0.07 ± 0.07 0.00 ± 0.00 Tree Class None Very Few None 0.00 ± 0.00 0.54 ± 0.44 0.00 ± 0.00 Very Few Few Moderate Gravel Class* 1.28 ± 1.28 2.86 ± 0.88 7.33 ± 4.33 Log Class None Few None 0.00 ± 0.00 1.57 ± 0.98 0.00 ± 0.00 Woody Vegetation None Very Few None Class 0.00 ± 0.00 0.39 ± 0.24 0.00 ± 0.00 Rushes Class Few Very Few None 1.33 ± 1.08 0.54 ± 0.39 0.00 ± 0.00 Sage Class None None Few 0.00 ± 0.00 0.00 ± 0.00 4.50 ± 1.26 * Significant at the 0.05 level. ** Significant at the 0.001 level.
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Table 16. Summation of microhabitat variable measurements grouped by sex class rather than by axis score. Variables are given a relative measure description (none, few, moderate, many and etc.) for each sex class as well as the mean and standard error for each combination of variable and habitat type. Male Female Subadult Variables n = 23 n = 15 n = 10 LargeLarge Large Surface Canopy 79.78 ± 6.26 77.19 ± 7.57 57.00 ± 5.39 Avg. Vegetation Medium Short Tall Height 13.09 ± 3.38 10.96 ± 3.31 30.14 ± 1.93 Few Few Many Sedge Class** 5.22 ± 2.49 2.00 ± 1.55 27.50 ± 2.94 Few Few Few Grass Class 0.52 ± 0.25 3.88 ± 1.46 1.70 ± 0.96 Few Few Many Willow Class** 1.61 ± 1.44 2.88 ± 2.62 12.50 ± 3.14 Few Very Few None Water Class 1.83 ± 1.47 0.13 ± 0.13 0.00 ± 0.00 Few Few Very Few Soil Class* 2.13 ± 0.72 5.00 ± 1.21 0.30 ± 0.21 Moderate Moderate None Rock Class* 10.52 ± 2.42 11.44 ± 3.22 0.00 ± 0.00 Few Few None Duff Class** 3.26 ± 1.33 3.13 ± 1.48 0.00 ± 0.00 Few Few None Lupine Class 3.83 ± 1.71 1.56 ± 0.74 0.00 ± 0.00 Herbaceous Moderate Moderate None Vegetation Class 5.61 ± 1.74 6.94 ± 1.94 0.00 ± 0.00 Very Few Very Few None Moss Class 0.22 ± 0.15 0.06 ± 0.06 0.00 ± 0.00 Very Few None None Tree Class 0.65 ± 0.53 0.00 ± 0.00 0.00 ± 0.00 Few Few None Gravel Class* 4.00 ± 1.41 2.13 ± 0.87 0.00 ± 0.00 Few Very Few None Log Class 1.35 ± 1.17 0.81 ± 0.47 0.00 ± 0.00 Woody Vegetation Very Few Very Few None Class 0.39 ± 0.29 0.25 ± 0.17 0.00 ± 0.00 Very Few Very Few None Rushes Class 0.43 ± 0.43 1.81 ± 1.22 0.00 ± 0.00 Very Few Very Few None Sage Class 0.43 ± 0.33 0.06 ± 0.06 0.00 ± 0.00 * Significant at the 0.05 level. ** S ignificant at the 0.001 level.
350
FIGURES
Distance to nearest tree within each Quadrant, N DBH and species class also recorded
Toad Location Distance to nearest willow patch within each Quadrant
Quadrant I Quadrant II
Quadrant IV Quadrant III
Distance to nearest 1 m Distance to water source within nearest rock ≥ 30cm each Quadrant within each Quadrant
Figure 1. Macrohabitat sampling arrangement for toad locations (After Reinert 1984).
351 Macrohabitat Group Case Scores
3.5 3 2.5 2 1.5
352 1
Axis 2 0.5 0 -1.5 -1 -0.5-0.5 0 0.5 1 1.5 2 2.5 -1 -1.5 Axis 1
Meadow Upland Overwinter
Figure 2. Scatter plot of macrohabitat axis 1 and 2 correspondence analysis case scores by habitat class. Macrohabitat Sex Group Case Scores 3.5 3 2.5 2 1.5
353 1
Axis 2 0.5 0 -1.5 -1 -0.5-0.5 0 0.5 1 1.5 2 2.5 -1 -1.5 Axis 1
Male Female SubAdult Juvenile
Figure 3. Scatter plot of macrohabitat axis 1 and 2 correspondence analysis case scores by sex class. Highly Significant Macrohabitat Variable Scores 100% 60 90% 80% 50 70% 40
60% Meters 50% 30
354 40% 30% 20 20% 10 Square Coverage Meter 10% 0% 0
-1.30 -1.12 -0.93 -0.89 -0.79 -0.71 .53 -0.66 -0 -0.41 0.06 Axis-0.32 1 0.77 0.95 1.16 56 1. 1.75 2.23 Woody Veg. Coverage Rock Coverage Duff Coverage Log Coverage Avg. Distance to Rock
Figure 4. Highly Significant macrohabitat variable scores for axis 1. Highly Significant Macrohabitat Variable Scores 70% 60% 50% 40% 30% 355 20%
Square MeterCoverage 10% 0%
.03 .85 6 -1.26 -1 .7 3 -0 -0.80 -0 .6 .55 7 -0.69 -0 .2 1 3 -0 -0.38 -0 .1 .12 9 Axis 2 -0.25 -0 0 0.5 .67 1 1.8 2.93 Gravel Coverage
Figure 5. Highly significant macrohabitat variable scores for axis 2. Non-significant Habitat Variables
100% 80% 90% 70%
80% Canopy Overstory 60% 70% 60% 50% 50% 40%
356 40% 30% 30% 20% 20% Square Meter Coverage 10% 10% 0% 0%
30 93 .79 53 32 0 06 95 .56 -1. -1.12 -0. -0.89 - -0.71 -0.66 -0. -0.41 -0. 0. 0.77 0. 1.16 1 1.75 2.23 Axis 1
Water Coverage Soil Coverage Herb Coverage Gravel Coverage Canopy Cover
Figure 6. Nonsignificant macrohabitat coverage variable scores for axis 1. Non-significant Macrohabitat Distance Measurements 120
100
80
60 Meters 357 40
20
0
-1.30 -1.12 -0.93 -0.89 -0.79 -0.71 -0.66 -0.53 -0.41 -0.32 0.06 Axis 1 0.77 0.95 1.16 1.56 1.75 2.23 Avg. Distance to Willow Avg. Distance to Burrow Avg. Distance to Water Avg. Distance to Tree
Figure 7. Non-significant macrohabitat distance variable scores for axis 1. Macrohabitat Water Variable Measurements 60
50
40
30 Meters 20 358
10
0
0 2 3 9 9 -1.3 1 -1.1 -0.9 -0.8 2 -0.7 -0.7 -0.66 .3 -0.53 -0.41 -0 0.06 Axis 1 0.77 0.95 1.16 1.56 1.75 2.23 Avg. Distance to Water Min. Distance to Water
Figure 8. Comparison between the average distance to nearest watersource measurement used as a macrohabitat variable in the analysis and the minimum distance to water measurement for each survey location plotted against axis 1. Overwinter Axis 1 Upland Meadow 2 1 0 -1 -2 2.5 1.5 0.5 -0.5 -1.5 -2.5 Macrohabitat Group Case Scores Case Group Macrohabitat Scatter plot of macrohabitat axis 1 and 3 correspondence analysis case scores by habitat class. Notice
-1.5-1-0.500.511.522.5 Axis 3 Axis Figure 9. that both meadow and upland habitat groups exhibit a greater verticle spread in case score values when plotted against axis 3 than when plotted 2 in Figure 2.
359
1.675
1.129
0.786
0.542
0.439
0.304 Coverage Log 0.234
Axis 3
0.078 -0.076
Woody Veg. Coverage Woody
-0.133
-0.475 -0.616
Significant Macrohabitat Variable Scores Variable Macrohabitat Significant
-1.008
-1.306 -1.818
Significant macrohabitat variable scores for axis 3.
0% -1.912
90% 80% 70% 60% 50% 40% 30% 20% 10% Square Meter Coverage Meter Square ure 10. g Fi
360 Winter Upland Axis 1 Meadow 3 2 1 0 -1 -2 2.5 1.5 0.5 -0.5 -1.5 Microhabitat Group Case Scores Case Group Microhabitat Scatter plot of microhabitat axis 1 and 2 correspondence analysis case scores by habitat class.
-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 Axis 2 Axis ure 11. g Fi
361 Juvenile SubAdult Axis 1 Female 3 2 1 0 Male -1 -2 2.5 1.5 0.5 -0.5 -1.5 Microhabitat Sex Group Case Scores Case Group Sex Microhabitat Scatter plot of microhabitat axis 1 and 2 correspondence analysis case scores by sex class.
-1.5-1-0.500.511.522.5 Axis 2 Axis ure 12. g Fi
362 Centimeters 70 60 50 40 30 20 10 0 Avg. Vegetation Height Vegetation Avg. Soil Rock Axis 1 Gravel Duff Significant Microhabitat Variables Sedge Willow Significant microhabitat variable scores for axis 1. -1.15 -0.87 -0.83 -0.72 -0.53 -0.40 -0.27 -0.24 0.11 1.32 1.56 1.74 1.94
5 0
45 40 35 30 25 20 15 10 Frequency ure 13. g Fi
363 Canopy Cover 100% 80% 60% 40% 20% 0% COVSCN Sage Rushes WoodyVeg. Log Axis 1 Axis Tree Moss Non-significant Microhabitat Variables Microhabitat Non-significant Herb Lupine Non-significant microhabitat coverage variable scores for axis 1. -1.15 -0.87 -0.83 -0.72 -0.53 -0.40 -0.27 -0.24 0.11 1.32 1.56 1.74 1.94
5 0
Wate r 45 40 35 30 25 20 15 10 Frequency ure 14. g Fi
364
.35
2
6
2.0
14
1.
.74
0
6
0.1
-0.02
4
1
-0.
9
.1 Duff -0
Axis 2 -0.23
Lupine
-0.37
-0.39
3
.4 -0
Significant Microhabitat Variables Microhabitat Significant
-0.57
-0.74
0
.0
-1 -1.54
Significant microhabitat variable scores for axis 2. 4
5 0 7
35 30 25 20 15 10 -1. Frequency ure 15. g Fi
365 APPENDIX 1 ad 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.5 0.1 0.1 0.1 plot; plot; PLOTID=Plot Bufo canorus. Upland Burrow Soil Med Upland Burrow Soil Low Upland Active Soil Med Upland Burrow Soil Dry Upland Active Water Wet Upland Burrow Gravel High Upland Burrow Soil Med Upland Burrow Rock Med Upland Burrow Soil Med Upland Burrow Soil Low MeadowMeadow Active ActiveMeadow SoilMeadow Active Active Soil High Wet Soil High Med Meadow Active SoilMeadow Active Wet Soil Wet Meadow Basking Gravel High Meadow Active Soil Wet Meadow Basking Soil Wet Meadow Active Soil Wet Meadow Active Soil Wet Meadow Active Soil Wet 1 1 1 1 2 2 1 1 1 1 5+ 5+ 5+ 6+ 6+ 4+ 4+ 4+ 4+ 4+ 6+ 8+ Male Male Male Male Male Male Male Male Female Female Female Female Juvenile Juvenile Juvenile Juvenile Juvenile Juvenile Juvenile Juvenile SubAdult SubAdult Class, climatic and structural variables collected at 49 post-reproductive habitat plots utilized by plots utilized by 49at habitat variables post-reproductive collected structural and climatic Class, 456 157 158 159 2yr 15 1yr#1 15 1yr#2 8/ 27/1997 8/ 27/1997 15 2yr 3:45 PM 8/ 3:59 27/1997 PM 1yr#3 4:02 PM 1yr#4 184 8/ 27/1997 118 8/ 27/1997 3:50 PM 119 8/ 4:05 27/1997 PM 4:08 PM 116 120 121 23 22 22 8/ 23/1997 4:30 PM 163 22 22 21 7/ 28/1997 12:55 PM 163 24 21 16 8/ 13/1997 9:01 AM 106 21 22 20 7/ 28/1997 8:38 AM 163 10 15 1yr#5 8/27/1997 PM 4:10 122 25 15 17 8/ 23/1997 4:20 PM 106 20 21 20 8/ 24/1997 3:17 PM 127 19 21 15 7/ 26/1997 11:00 PM 127 18 21 17 8/ 12/1997 11:24 PM 127 17 21 21 8/ 25/1997 10:30 AM 127 11 15 1yr#6 8/27/1997 PM 4:11 123 16 21 19 8/ 23/1997 7:23 PM 127 12 15 1yr#7 8/27/1997 PM 4:12 124 15 22 13 7/ 27/1997 1:46 PM 106 13 15 1yr#8 8/27/1997 PM 4:13 114 14 22 5 7/26/1997 PM 10:20 129 PLOTID SITEID FLAGNUM DATE TIME TOADID CLSSEX AGE CLSHBT CLSACT CLSSUB CLSSMO AMTPPT Appendix 1. Continued next page. identification number; SITEID=Site identification number; FLAGNUM=Site flag number; DATE=Date of encounter with toad in habitat toad SITEID=Siteof DATE=Date number; number; with FLAGNUM=Site encounter number; identification flag identification plot; CLSSEX=Sex individual; in TOADID=Toad number; AGE=Estimated to habitat of toad encounter ofTIME=Time identification with CLSSMO=Substrate Moisture; CLSSUB=SubstrateCLSACT=Toad AMTPPT=Precipitation CLSHBT=Habitat class; activity; age; class; amount.
366 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 0.1 0.1 0.1 0.1 0.1 0.01 Winter Burrow Soil Dry Winter Burrow Soil Dry Winter Burrow Soil Dry UplandUpland Active Active Rock Soil Med High Upland Burrow Soil Med Upland Burrow Soil Med Upland Active Soil Low Upland Active Rock Dry Upland Basking Soil Med Upland Burrow Soil Dry Upland Active Rock Dry Upland Burrow Soil Med Upland Burrow Soil Low Upland Basking Soil High Upland Basking Soil Low UplandUpland Burrow Burrow Soil Soil Low Dry Upland Basking Soil Med UplandUpland Burrow Active Soil Soil Low Med Meadow Active Soil Dry Meadow Basking Soil Med Meadow BaskingMeadow Soil BurrowMeadow Burrow Soil High Soil High High Meadow Active Soil High 3 8+ 5+ 4+ 4+ 4+ 5+ 4+ 8+ 6+ 6+ 5+ 4+ 5+ 4+ 8+ 8+ 6+ 5+ 5+ 4+ 8+ 6+ 6+ 4+ 6+ 10+ Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Male Female Female Female Female Female Female Female Female Female Female Female 37 23 17 12/10/1995 PM 3:01 16 36 23 6 10/23/1995 11:10 PM 46 383940 16 21 21 7 12 9 10/23/1995 12:30 7/24/1997 PM 10:30 7/16/1997 PM PM 12:23 21 127 127 35 21 14 7/24/1997 9:35 PM 163 41 21 13 7/25/1997 8:45 AM 127 293031 24 15 21 19 12 2 8/26/1997 7/23/1997 5:45 PM 10:05 7/26/1997 PM PM 10:44 106 128 163 27 15 18 8/24/1997 3:39 PM 106 34 21 13 7/24/1997 7:36 AM 163 42 21 11 7/24/1997 10:36 AM 127 50 22 1 7/24/1997 AM 8:12 129 51 22 11 7/24/1997 8:12 AM 106 3233 21 21 origin 11 7/25/1997 9:48 PM 7/23/1997 125 7:07 PM 163 43 21 6 7/4/1997 AM 11:50 127 47 22 8 7 & 12, 7/25/1997AM 8:10 106 48 22 3 7/25/1997 AM 8:10 129 49 22 2 7/24/1997 PM 9:54 129 52 21 15 7/25/1997 8:01 AM 163 53 22 16 7/25/1997 1:30 PM 163 54 22 9 7/23/1997 PM 6:33 106 444546 21 225 & 10 22 7/23/1997 PM 4:50 10 4 127 7/23/1997 7/26/1997 9:42 PM AM 2:44 129 106 PLOTID SITEID FLAGNUM DATE TIME TOADID CLSSEX AGE CLSHBT CLSACT CLSSUB CLSSMO AMTPPT Appendix 1 (continued). Continued next page.
367 0%0%0% 3%0% 10%0% 0%0% 0% 5% 0%0% 5%0% 0% 5% 0%0% 0% 0% 1%0% 0% 2% 0%0% 5% 0% 0% 0% 0%0% 0% 5% 0%0% 0% 0% 65% 2% 0%0% 70% 0% 0% 10% 0%0% 0% 0% 60% 0% 0% 25% 40% 0% 10% 80% 0% 35% 0%0% 0% 55% 0% 0% 40% 70%0% 20% 0% 2% 19% 0% 15% 10% 70%0% 0% 30% 50% 40% 20% 0% 1% 0% 30% 0% 88%0% 0% 70% 1% 15% 0% 30% 70% 49%0% 5% 0% 95% 30% 38% 10% 0% 30% 15% 40% 25% 14% 0% 30% 10% 0% 55% 10% 0% 0% 2% 0% 10% 0% 5% 0% 2% 0% 0% 5% 5% 10% 0% 0% 0% 0% 10% 1% 0% 0% 20% 0% 25% 11% 27% 0% 27% 0% 0% 15% 0% 35% 5% 85% 5% 0% 0% 5% 50% 0% 40% 0%10% 10% 15% 0% 30% 0% 3% 10% 0% 10% 40% 30% 0% 2% PLOTID=Plot identification number; COVSCN=Canopy closure at toad level; COVCN=Canopy closure closure toad COVCN=Canopy atlevel; closure COVSCN=Canopy number; PLOTID=Plotidentification 410%2% 58%4% 614%2% 78%4% 816%2% 916%2% 20 20%24 6% 2% 1% 101112 12%13 14%14 3% 8%15 4% 8%16 19% 4% 17 17% 4% 18 20% 7% 19 12% 20% 20% 7% 21 7% 0%22 6% 23 20% 0% 20%25 18% 5% 3% 16% 6% 2% PLOTID COVSCN COVCN COVWTR COVSOL COVRCK COVDUF COVLOG COVHVG COVWVG COVGVL at 1m height; COVWTR=Water coverage within 1-m2 plot; COVSOL=Soil coverage; COVRCK=Rock coverage; COVDUF=Duff COVDUF=Duff coverage; COVRCK=Rock coverage; COVSOL=Soil plot; 1-m2 within coverage COVWTR=Water height; 1m at COVWVG=Woody vegetation coverage; coverage; vegetation COVLOG=Log coverage; COVHVG=Herbaceous coverage; COVGV L=Gravel coverage ordered0-20 with a 5% interval. Appendix 1(continued). page. next Continued
368
0%0%5% 5%0% 1%0% 0%0% 0% 25%0% 0% 25%0% 0% 13% 45% 0%0% 55% 5% 0%0% 13% 0% 0% 3%0% 0% 2% 3%0% 0% 0% 10% 0% 0% 0% 0% 95% 3% 70%0% 0% 24% 0% 0% 0%0% 0% 10% 0% 25%0% 12% 0% 1% 5% 15% 75%0% 10% 5% 0% 5% 85% 0%0% 70% 85% 0% 50% 0% 0% 0% 55% 0% 45% 0% 0% 95% 0% 25%0% 85% 15% 0% 0% 30% 0%0% 2% 5% 9% 10% 15% 20%0% 2% 15% 0% 0% 30% 30% 0% 5% 8%0% 30% 2% 45% 15% 0%0% 3% 0% 15% 0% 95% 55% 0% 5%0% 0% 2% 55% 0% 2% 25% 4%0% 35% 60% 0% 15% 55% 60% 5%0% 0% 10% 20% 10% 5% 90% 0% 1% 15% 5% 0% 2% 90% 0% 40% 0% 2% 0% 0% 5% 5% 0% 30% 35% 0% 5% 2% 0% 10% 0% 20% 0% 1% 10% 0% 2% 0% 0% 0% 21% 0% 2% 0% 0% 0% 0% 5% 2% 5% 0% 5% 1% 0% 34% 50% 0% 0% 0% 0% 75% 0% 1% 0% 0% 0% 45% 0% 0% 30% 10% 10% 5% 0% 45% 0% 0% 272930 14%31 19%32 20% 2% 33 18% 2% 34 0% 3%35 10% 6% 36 10% 3% 37 0% 6%38 1% 0%39 0% 0% 40 20% 8% 41 19% 7% 42 17% 6% 43 20% 2% 44 17% 4% 45 10% 9% 46 20% 6% 47 12% 8% 48 20% 5% 49 20% 4% 50 20% 5% 51 12% 13%52 12% 20%53 20% 7% 54 20% 7% 7% 8% 16% 2% 6% 10% PLOTID COVSCN COVCN COVWTR COVSOL COVRCK COVDUF COVLOG COVHVG COVWVG COVGVL Appendix 1 (continued). Continued next page. next Continued
369
1 1 1 2 1 1 2 1 1 1 1 1 4 4 3 4 4 2 2 1 1 3 5 10000 210 0 10 602 22 25 15 845 671 800 22 15 65 1370 2560 510 20202926 2 113 2860 48 29 130 210 478 2005 3850 3180 640 1676 720 41 1090 0 710 194 115 36 10000 15 0 5 270 36 10000 15 0 5 270 11 10000 32 0 15 865 33 10000 15 1320 8 40 20 54 95 1970 1007 1210 116 15 92 622 465 476 245 910 42 890 12 1445 108 4330 10 3860 19 1180 113 140 173 135 6880 7070 310 220 20 58 4 2705 1 1 1 1 3 2 1 3 3 1 1 3 3 2 1 1 3 PLOTID=Plot identification number; DSTRCK#=Distance (cm) to nearest rock within each quadrant; each quadrant; within rock to nearest (cm) DSTRCK#=Distance number; PLOTID=Plot identification 0220 0724 15 960 15 960 50 830 20 1045 13 87 25 420 24 895 18 3105 985 2408 1381 7890 1810 8490 36303340 100003405 100002200 10045 8880 10 0 38 101 3880 3480 1820 1850 1045 1000 49904435 100004140 10000 10000 5 10 10 34 91 33 1290 4275 1955 4420 580 365 641 937 945 8750 8676 6880 6775 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 25 24 PLOTID DSTRCK1 DSTTRE1 CLSTRE1 DIMTRE1 DSTWLW1 DSTBRW1 DSTWTR1 DSTRCK2 DSTTRE2 CLSTRE2 DSTTRE#=Distance to nearest tree within each quadrant; CLSTRE#=Tree Classified as 1-Lodgepole, 2-Hemlock, 3-Whitebark; 3-Whitebark; 2-Hemlock, 1-Lodgepole, CLSTRE#=Tree as Classified quadrant; each to within tree nearest DSTTRE#=Distance quadrant; DSTBRW#=Distance each within willow nearest DSTWLW#=Distanceground; to ~1.25 mat above of tree DIMTRE#=Diameter quadrant. each within source water nearest DSTWTR#=Distance eachto quadrant; within burrow nearest to (cm) Appendix 1(continued). page. next Continued
370 1 3 1 2 1 1 4 1 3 1 1 3 3 3 4 1 1 1 1 1 1 1 1 1 1 1 1 0 6 1430 5810 4630 017501125000325 6 3655 260 2450 0 448 0 271 31 3500 320 205 6 3655 260 2450 0 448 4 10000 277 10000 14 775 6 10000 52 2060 49 165 18 965 47 1430 0 670 21 1150 16 245 0 354 80 7400 168 22 780 520 95 1140 125 240 30 830 53 5440 163 2820 685 267 11 10000 20 10000 17 412 18 4300 160 3330 0 276 28 10000 5 10000 20 560 18 965 47 1430 0 670 27 10000 38 380 3 200 22 10000 30 0 0 946 138573 10000 480 1980 48 250 670 1630 1160 2290 2410 4800 2460 4720 1943 1119 21 95 120 2290 3040 1115 22 0 25 2210 3210 1190 149 9530 225 10000 78 182 185 10000 405155 1175 10000 55 6 110 148 0 680 101 500 620 1740 593 432 1 1 1 1 1 1 1 3 1 3 1 3 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 0685 0413 0433 31405 0361 0361 0776 0685 22050 0195 0530 0882 55 1260 75 785 12 730 17 575 13 325 61 1035 19 190 169 773 236048405900 4520 4850 1120 5770 702 2035 8676 1955 8600 10000 10000 47 54 46 52 53 45 51 44 50 43 49 42 48 41 40 31 32 33 34 35 36 37 39 27 29 30 38 PLOTID DSTRCK1 DSTTRE1 CLSTRE1 DIMTRE1 DSTWLW1 DSTBRW1 DSTWTR1 DSTRCK2 DSTTRE2 CLSTRE2 Continued next page. next Continued Appendix 1(continued).
371 st within within 0010124 00861 07225 207 243 004 100000 100000 10000 52 10000 52 10000 34 410 380 029284 0243 21635 6566 1805 2200 557 100 24 3040 170 14 1470 120 33 3180 15 53 103 319 20 25 522 40 37 675 115 957 34 116 122 140 1 1 1 1 1 2 1 3 4 3 4 3 2 3 3 1 1 1 1 1 1 2 PLOTID=Plot identification number; DIMTRE#=Diameter of tree at ~1.25 m above ground; DSTWLW#=Distance ground; ~1.25 m above at tree DIMTRE#=Diameter PLOTID=Plotof number; identification 06 15 15 28 33 185 100 570 456 700 840 0 2170 360 120 64 410 9000 10000 10000 10000 37 10000 46 248 7 0 0 0 4270 5 15 10 9 1160 800 922 300 9 10000 37 0 5 1160 0 240 163 2780 3480 1092 6 430 450 90 332 307 767565 0 40 255 820 79 302 64 132 89 605 630 1550 960 1002 710 24 26 122 3600 0 115 30 806 22 1330 80 307 12 3430 15 2500 25 705 38 113 97 520 1007 1037 84 12 250 447 550 510 58 107 196 110 980 580 30 94 245 84 557 700 12 15 105 82 460 533 399 220 20 137 6 2712 8 9 4 5 6 7 10 11 12 13 14 15 17 18 19 20 21 16 22 23 24 25 PLOTID DIMTRE2 DSTWLW2 DSTBRW2 DSTWTR2 DSTRCK3 DSTTRE3 CLSTRE3 DIMTRE3 DSTWLW3 DSTBRW3 water source within each quadrant; DSTRCK#=Distance (cm) to nearest rock within each quadrant; DSTTRE#=Distance to nearest tree nearest DSTTRE#=Distance eachto quadrant; within rock nearest DSTRCK#=Distance to (cm) quadrant; within each source water 3-Whitebark. 2-Hemlock, CLSTRE#=Tree 1-Lodgepole, quadrant; as Classified each Appendix 1 (continued). Appendix DSTWTR#=Distance neare each quadrant; to within DSTBRW#=Distance nearest burrow quadrant; within to (cm) each nearest willow to page. next Continued
372 010000374 020510 37 1900 369 37 1900 369 97 85 113 681251 10000 5360 10000 20 88 45 97 85 113 40 10000 40 154913 10000 10000 10000 4 12 76 43 1590 86 55 330 380 23 700 440 5598 0 920 437 18 7656 1840 75 67 155 332 1380 105 215 10000 100 261 10000 25 114 7030 105 120120030 70 137 1 1 1 3 2 1 1 1 1 3 2 1 2 3 3 3 1 2 1 1 1 1 1 331131140 1 1 1 1 0 10000 245 25 36 837 4 10000 25 118 0 1314 0 1590 335 140 0 390 0 1240 340 1930 24 6300 19 6230 348 705 678 1085 13 2660 140 3330 0 1150 71 3140 460 850 330 550 4329 5115 10000 257 50 1200 0 38 0 174 1184 29 1550 130 240 55 1030 5137 1000030 10000 12 10000 9 10000 13 1450 5 1400 13 220 230 564 476 94 480 205 1500 3320 1848 31 151 60 580 965 995 38 0 27 600 1065 1110 58 75 134 2100 150 550 105 2125 240 2450 0 606 105 2125 240 2450 0 606 342 3060 120 3280 0 312 145 4330 80 180 0 490 342 3060 120 3280 0 312 119 3630 470 4600 2460 2310 112 330 200 840 5060 3810 120 1310 185 1750 86 393 117 0 42 70 3870 2505 300 65 6110 0 962 52 51 50 49 37 38 39 40 48 45 36 41 42 43 44 46 47 35 34 33 31 32 27 29 30 53 54 PLOTID DIMTRE2 DSTWLW2 DSTBRW2 DSTWTR2 DSTRCK3 DSTTRE3 CLSTRE3 DIMTRE3 DSTWLW3 DSTBRW3 Continued next page. Appendix 1 (continued).
373
0000 310 40 150 50 83 0 35 44 61 1015 120 1130 330 25 335 10000 0 10000 130 290 10000 105 330 10000 578 155 10000 1050 1320 15 10000 85 34 2400 1065 0 57 0 0 0 27 82 1320 1330 382 1940 754810 15 20 5 82 26 25 550 460 49 300 1045 1901432 155 780 515 320 28 850 39 117 103 185 113 1 1 1 2 2 2 1 1 2 1 2 2 1 1 1 3 3 1 2 3 1 2 PLOTID=Plot identification number; DSTWTR#=Distanceto nearest source water within 0 15 1475 000 15 24 45 1475 704 470 848281 3910 475 1138 4370 2933 718 9864 129588 158075 1162 2280 1440 0 2275 290 32 10 1505 300390 1215 1480 851 1170 295440 2200 3610 2452 2317 110 2510 1997 142 2150155 1850 0 1688 2560 7 730 42702400 38 18 280 540 5 6 7 8 9 4 16 22 24 25 10 11 12 13 14 15 17 18 19 20 21 23 PLOTID DSTWTR3 DSTRCK4 DSTTRE4 CLSTRE4 DIMTRE4 DSTWLW4 DSTBRW4 DSTWTR4
within each quadrant; CLSTRE#=Tree Classified as 1-Lodgepole, 2-Hemlock, 3-Whitebark; DIMTRE#=Diameter of of DIMTRE#=Diameter Appendix 1 3-Whitebark; (continued). 2-Hemlock, 1-Lodgepole, as each DSTTRE#=Distancenearest tree DSTRCK#=Distance quadrant; nearest rock within to quadrant; to (cm) each Classified CLSTRE#=Tree quadrant; each within at ~1.25tree m above ground; DSTWLW#=Distancenearest to willow within each quadrant;DSTBRW#=Distance quadrant. each each DSTWTR#=Distance within nearest quadrant; water within source nearest burrow to to (cm) page. next Continued
374
0 1050 130 1125 500 320 2980 0 3330 197 3340 0 1180 100 1480 53 6600 10 6280 13 0125824 3540 32 1030 1250 15 2820 5 53 590 2225 3150 86 10000 170 122 139118 390 3220 1071 430 192 90 970 1100 0 1018 10000 1010 535 30 10000 370 242330 1530 1970 2710 3 61 43 1000 10000 3500 38 3470 160 220 55 2670 94 74 2613 8513 1920 39 1920 474 474 410 2185 2185 26 85 39 410 116 0120 10 1175 1110 505 1790 1 2 1 2 1 1 2 1 1 1 1 1 1 1 3 1 3 3 1 2 2 3 3 2 1 1 70 487 47 140 0 1 0 755 0 0 1618 44 870 3400 25 25 853 90 0 1010 71 0 470 385520 2580 3530 2760 840 3320 9330 7320 130 70 1000 210 0 722 840 310 120 340 7 1110 410 0 869 410 0670 869 70 452 1280 99 101 59305040 4220 3660 3025 2430 1810 0 594 1028 20 242 11801400 18 60 660 442 2185 0 649 2185 0 649 1435 0 140 10000 2 1530 27 29 33 53 32 30 34 35 36 54 31 37 38 39 40 41 42 43 44 45 46 47 50 48 51 52 49 PLOTID DSTWTR3 DSTRCK4 DSTTRE4 CLSTRE4 DIMTRE4 DSTWLW4 DSTBRW4 DSTWTR4 Appendix 1 (continued). Continued next page. next Continued
375 10-Moss, 11- 10-Moss, PLOTID=Plot identification number; NSVGH##=Vegetation height or water depth intersecting the 1m N-S transect every transect N-S 1m the PLOTID=Plot water depth intersecting or NSVGH##=Vegetation height number; identification 1031013013 9 1151221231281 060606 0 642 0 6 0 6 00 6 6 0 0 6 6429 0 60130130130 0 6429 245464 7 474 050606 0 606 05050531131413 050505 0 707 05012012012012 9123 211191 201281 101171 291311 491281 373313 231221 191331 192152132 181221191 131121181 291261251 361251261 323343293 483433423 211221201 4116 321271 141191262 67 9 1141121121 11111 11 11 10 11 0 7 0 7 03 04 6 0 7 163 10943 10931 NSVGH00 NSVCLS00 NSVGH05 NSVCLS05 NSVGH10 NSVCLS10 NSVGH15 NSVCLS15 NSVGH20 NSVCLS20 4 5 6 7 8 9 10 11 12 13 15 16 17 18 19 20 22 23 24 25 14 21 PL OTID 5cm; NSVCLS##=Vegetation or water classified as 1-Sedge, 2-Grass, 3-Willow, 4-Water, 5-Soil, 6-Rock, 7-Duff, 8-Lupine,9-Herb, 6-Rock, 7-Duff, 5-Soil, 2-Grass, 3-Willow,classified1-Sedge, 4-Water, as NSVCLS##=Vegetation water 5cm; or Appendix 1 (continued). 1 (continued). Appendix 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, Tree, Continued next page.
376 19071418111181 6 8 9129 7 1 9 1203342232 0 5199 060606 0 606 494961591589 8151315815252192 0070707 0 707 0 6 0 6379 242414 1 404 7 7012 0 6109 050505 0 579 060606 27 0 606 06271591 070124130606 060606 6 0 9 606 9 3060606 9 0 4 606 9 060606 0 606 060606 0 0 606 057205 0 505 313222 12 0 12 0 12 0438 493543 169149 7981008 403483483 0 6128 141149159 3421513 778728648 189199339 4 9 5 9 162152132 609809109 NSVGH00 NSVCLS00 NSVGH05 NSVCLS05 NSVGH10 NSVCLS10 NSVGH15 NSVCLS15 NSVGH20 NSVCLS20 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 27 PL OTID Continued next page. Appendix 1 (continued). Appendix
377 Herb, 10- Herb, PLOTID=PlotN-S transect1m identification NSVGH##=Vegetation water number; the depth height or intersecting 0030 7 63116211 9 9102172202232 1 101033 013013013013013 6464542454 0606069906 0605050606 012012012012012 8339339 1 281301281311311 201191161161181 161403393353413 351271261191181 261331321311271 181291363313343 281363393383 251261241271241 231191261171171 261221151211201 5 01301305 3838 9 927130 10 0 0101131161101191 8 12 12 74 7 74 9 8 9 20 30 20 7 8 7 0 29 0 12 8 12 0 5 NSVGH25 NSVCLS25 NSVGH30 N SVCLS30 NSVGH35 NSVCLS35 NSVGH40 NSVCLS40 NSVGH45 NSVCLS45 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID every 5cm; NSVCLS##=Vegetation or water classified as 1-Sedge, 2-Grass, 3-Willow, 4-Water, 5-Soil, 6-Rock, 7-Duff, 8-Lupine, 9- 8-Lupine, 7-Duff, 6-Rock, 5-Soil, 4-Water, 3-Willow, 2-Grass, 1-Sedge, as 1 (continued). Appendix classified water or 16-Sage. NSVCLS##=Vegetation 5cm; 15-Rushes, every 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, Moss, Continued next page.
378 8 1151191241271 0606060606 89796917905 0 8 7 0 7 00707070707 7 012012 7 4 5 4288448478 4 9 0 51481687 0607070505 70606060606 0606060606 0606060606 9513382402182152 0606060606 0606060606 203959053905 69899912906 1 0 12 20 1 18 1 6327220 5 173222293243243 553603543623633 13906060606 311231271251161 262382372232 829849899959979 17806060606 489559709709729 10 2 1 8 0 12 18 2 14 2 NSVGH25 NSVCLS25 NSVGH30 NSVCLS30 NSVGH35 NSVCLS35 NSVGH40 NSVCLS40 NSVGH45 NSVCLS45 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PLOTID Appendix 1 (continued). Continued next page.
379 Herb, 10- Herb, PLOTID=Plot identification NSVGH##=VegetationN-S number; transect1m water height depthor the intersecting 103107 0 7 0 5393383333433 012012012012012 012012012012012 7 1111 0130130130 6464443434 0 6 0 0 6 6 0 012012012 0606060606 6 0505050505 0 5 01206 01205101 0329320 7 221211281352262 201181271411211 231383443453433 1181291 141261191151141 211201191311723 191191241211251 433383282361331 181191363453463 1511719 302322292312 64 11 0221261101301231 6 0 6 0 6 0 6 NSVGH50 NSVCLS50 NSVGH55 NSVCLS55 NSVGH60 NSVCLS60 NSVGH65 NSVCLS65 NSVGH70 NSVCLS70 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, Moss, every 5cm; NSVCLS##=Vegetation or water classified as 1-Sedge, 2-Grass, 3-Willow, 4-Water, 5-Soil, 6-Rock, 7-Duff, 8-Lupine, 9- 8-Lupine, 7-Duff, 6-Rock, 5-Soil, 4-Water, 3-Willow, 2-Grass, 1-Sedge, as classified Appendix 1water (continued). or NSVCLS##=Vegetation 5cm; every Continued next page.
380 102107 0 7 9 0606050505 0606060606 05893171151 0 5 0 51491096 0 9 5 0 5 8 1527152515 0120120120 0707070707 3 7 0 62391297 2 8 4 8368368328 05050606012 5 1 01201201305 0606062905 0606060506 0606060506 4206060606 012012 0606060606 0606060606 0 5 01252 0 5 1 2 306415912959 2 012012 8216 9 1 7 1 1403413 281241161 3233139 543613403483453 0 5148398498 359429388488498 468 689539669559549 NSVGH50 NSVCLS50 NSVGH55 NSVCLS55 NSVGH60 NSVCLS60 NSVGH65 NSVCLS65 NSVGH70 NSVCLS70 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PLOTID Appendix 1 (continued). Continued next page.
381 - oil, 6-Rock, 7 PLOTID=PlotN-S transect1m identification NSVGH##=Vegetation water number; the depth height or intersecting 199 9179229 8 9119 0606060606 012012012012012 012012012012012 060606013013 3444445454 0505050549 0 7 0 7 00606060614 7209289 432353422312262 22353363373353473 151121583221402 663623523563563 1281241261241231 393383343333293 311321261241251 303423563543523 9281321321261311 1 1 4 1121 1214 11511018 1510 41 22 1 3 15 4 42 29 1 3 9 13 22 1 15 12 23 1 15 12 1 NSVGH75 NSVCLS75 NSVGH80 N SVCLS80 NSVGH85 NSVCLS85 NSVGH90 NSVCLS90 NSVGH95 NSVCLS95 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID Appendix 1 (continued). 1 (continued). Appendix ordered 5cm 2-Grass, NSVCLS##=Vegetation with interval; 1-Sedge, 3-Willow,a 3cm 5-S as every water 0-40 4-Water, classified or Continued next page. Duff, 8-Lupine, 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, 10-Moss, 9-Herb, 8-Lupine, Duff,
382 11310510101 7 1121 0507070707 0606271728 6 0 6 0707223242 0707070606 9 0120120120 3 9 6 91491293 0606060605 0606060605 5232060606 0606070606 4 9 20606060706 8 2952420705 5 9 01259 5989992906 283583593603663 393513453293333 211191241241251 8288448 119056911269 6 0 6268 10 15538548568508209 1281187 1891990 6579359588608588 30805050505 23148914769 8 9 15 17 15 0 5 NSVGH75 NSVCLS75 NSVGH80 NSVCLS80 NSVGH85 NSVCLS85 NSVGH90 NSVCLS90 NSVGH95 NSVCLS95 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PLOTID Appendix 1 (continued). Continued next page.
383 Soil, 6- upine, WEVGH00 WEVCLS00 WEVGH05 WEVCLS05 WEVGH10 WEVCLS10 WEVGH15 0 PLOTID=Plot identification number; NSVGH##=Vegetation height water or depth intersecting1mN-S the SVCLS10 N 10 06060 06060 065 9 33927911 01206 01206 0130130120120 24345 4406 060 5 0 5 0120 1 4 95 8 95 8 32 8 0 34344832 242 327 06060 323 222 44 3 4156 07060 125 58 329906 42 1 3 73 3 1 47 1 3 38 1 21 49 3 48 18 3 13 59 3241507 1 33 1 910 1 3 8 75 3 129 1 40 11710120120120 3 381218 3 2 24 47 3 49 27 3 12 49 3 36 7 1 3 72 3 1 32 1 3 37 1 13 19 27 3 56 49 3 14 47 3 32 0 1 80 3 26 1 39 24 7 48 25 0 7 0 NSVGH100 5 6 7 8 9 4 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage; WEVGH##= Vegetation height or water depth depth water or height Vegetation WEVGH##= 16-Sage; 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, 16-Sage. 10-Moss, 15-Rushes, 9-Herb, 14-WoodyVeg, 13-Log, 5- 4-Water, 3-Willow, 1-Sedge, 2-Grass, as classified water 12-Gravel, or WEVCLS##= Vegetation 5cm; every transect W-E 1m 11-Tree, the intersecting 10-Moss, 9-Herb, 8-Lupine, 7-Duff, Rock, Appendix 1 (continued). 8-L 7-Duff, 6-Rock, 4-Water, 5-Soil, 3-Willow, 1-Sedge, 2-Grass, as classified water or NSVCLS##=Vegetation 5cm; every transect Continued next page.
384 WEVGH00 WEVCLS00 WEVGH05 WEVCLS05 WEVGH10 WEVCLS10 WEVGH15 0 SVCLS10 N 11116115120 510161 06060 3806 070120120120 292 9 2 9 5915211518159816 912 31212 2241 00 7 6066149145146 06013013070 898 1 13115121 049139189490 34 06060 0606 06060 0606 39060 50632 6 0 06060 5 80606 0 123 06060 0606 0120 380120120120 16 220 16 8 6 14 17 23 16 15 8 0 19 40 15 20 15 12 67 5 338 9 9 919 31510 3 30 43 351 33468 8 28 8 44 8 0 3 23 3 62 12 20 9 46 9 0 2 9 3 63 12 12 55 9 9 17 10 48 2 9 9 0 7 43 NSVGH100 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PLOTID Continued next page. Appendix 1 (continued).
385 Lupine, Lupine, PLOTID=Plotidentification number; WEVGH##= Vegetation heightwater or depth intersecting 1m the W-E 1381411411301 3593543453411 8 1303353 3503493523603 1331331331291 3663281311313 3303 3413393433423 6 1292273221331 3463433563583 1281111101151 606060606 149060606 606060606 606060606 444241434 72392492190 50531491407 606060606 1311191181171 210260 6 12013013013013 1201201206 12012012012012 WEVCLS15 WEVGH20 WEVCLS20 WEVGH25 WEVCLS25 WEVGH30 WEVCLS30 WEVGH35 WEVCLS35 5 6 7 8 9 4 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID Appendix 1 (continued). transectevery 5cm; WEVCLS##= Vegetation or water classified as1-Sedge, 2-Grass,3-Wi llow,4-Water, 5-Soil, 6-Rock, 7-Duff, 8- Continued next page. 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, 10-Moss, 9-Herb,
386 19859221 1181181181221 3353363283263 3543393523473 606060606 705050606 91591895 8 8 8459789539 757579979 607060607 8458488558548 906060606 9469709769629 606060606 6 1191331371211 6 5470707129 5 9 1 0 11290 5 9 1 0 51290 60606141306 607715161 607715161 90124801242 15159057939 12 9 4 9 14 5 16 9 14 5120121294 1715 9 14 14 40 0 15 8 24 5 52 15 8 8 17 8 15 0 6 WEVCLS15 WEVGH20 WEVCLS20 WEVGH25 WEVCLS25 WEVGH30 WEVCLS30 WEVGH35 WEVCLS35 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 27 PLOTID Appendix 1 (continued). Continued next page.
387 Lupine, Lupine, PLOTID=Plot identification number; WEVGH##= Vegetation heightwater or depth intersecting1m the W-E 10210 0 0 0 06423028920 001201201206 01201201206 0130130130130 6444464442 060606990 060606060 050505050 7106050529833 01201201205 11 64 11 63 11 11 271251221617 0210210 23125122120119 401251201261 52342323132127 27128126118119 34318121120171 15118119122127 40361053126 39343343331131 61355318119112 21118115115121 WEVGH40 WEVCLS40 WEVGH45 WEVCLS45 WEVGH50 WEVCLS50 WEVGH55 WEVCLS55 WEVGH60 4 5 6 7 8 9 15 16 17 18 19 20 21 22 23 24 25 10 11 12 13 14 PLOTID 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, 10-Moss, 9-Herb, transect every 5cm; WEVCLS##= Vegetation or water classified as 1-Sedge, 2-Grass, 3-Willow, 4-Water, 5-Soil, 6-Rock, 7-Duff, 8- 7-Duff, 6-Rock, 5-Soil, 4-Water, 3-Willow, 2-Grass, 1-Sedge, as 1 (continued). classified water or Appendix Vegetation WEVCLS##= 5cm; every transect page. next Continued
388 105 0 512922 060606050 060606060 8150 0532055215 991290120120 070707070 050537050 050505060 0120606060 060606060 060606060 060642529 060606060 060606060 820505724 050505489 060606064 24126127124123 32327334329326 8 858 51346354352351 161050512125 48847835942991 508518468 69970968956918 10898282832 17 1 21 1 5 1 6 1 10 WEVGH40 WEVCLS40 WEVGH45 WEVCLS45 WEVGH50 WEVCLS50 WEVGH55 WEVCLS55 WEVGH60 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PLOTID Continued next page. next Continued Appendix 1 (continued). Appendix
389 Lupine, Lupine, PLOTID=Plot identification number; WEVGH##= Vegetation height or water depth intersecting the 1m W-E 1m W-E the intersecting depth water or height Vegetation WEVGH##= number; identification PLOTID=Plot 11151 7 1 11811115 5 8 2121141221 1291261251381 1211221161161 3653613343221 1321321331381 1373383443241 0 7149219 1301321361371 1261241261311 1271231301291 2212 8 2 940912965116611 606060606 606060606 406060606 6 514614514012 5 01301305 8 348132914091379 505050505 1121141151161 310 0 7 0 7 1301307 1305050506 WEVCLS60 WEVGH65 WEVCLS65 WEVGH70 WEVCLS70 WEVGH75 WEVCLS75 WEVGH80 WEVCLS80 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PLOTID Appendix 1 (continued). 8- 7-Duff, 6-Rock, 4-Water, 3-Willow, 5-Soil, 1-Sedge, 2-Grass, as classified water or WEVCLS##= Vegetation 5cm; every transect Continued next page. 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, 14-WoodyVeg, 13-Log, 12-Gravel, 11-Tree, 10-Moss, 9-Herb,
390 1261241251291 3303379101243 3413433483363 506060607 606060607 114105110131 9129109715149 81289152615915 79959979979929 8558428488128 606060606 09179239219209 8448508508348 606060606 1199149418618 7606060606 606060606 2060605382 9606060606 606060606 83801201239 1151201303313 16906060606 11 16 3 16 12012012012209 1205396249 WEVCLS60 WEVGH65 WEVCLS65 WEVGH70 WEVCLS70 WEVGH75 WEVCLS75 WEVGH80 WEVCLS80 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 27 PLOTID Appendix 1 (continued). Continued next page.
391
PLOTID=Plot identification number; WEVGH##= Vegetation height or water depth intersecting the the intersecting depth water or height Vegetation WEVGH##= number; identification PLOTID=Plot 8 1171151201 060606 0 6 060606 0 0 6 7 060606 0 6 050707 12 0 7 6212205 060606 0 6 05050120 212592 241201271241 501461481461 181161261151 191251533483 431411401391 282201241221 341361301281 221171191161 231251261261 1291321529 58 11169179119129 59151121221211 11 54 11 50 11 139 9 112 9 119 9 105 9 WEVGH85 WEVCLS85 WEVGH90 WEVCLS90 WEVGH95 WEVCLS95 WEVGH100 WEVCLS100 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 PL OTID Rock, 7-Duff, 8-Lupine, 9-Herb, 10-Moss, 11-Tree, 12-Gravel, 13-Log, 14-WoodyVeg, 15-Rushes, 16-Sage. 15-Rushes, Appendix 1 (continued). 14-WoodyVeg, 13-Log, 6- 4-Water, 5-Soil, 1-Sedge, 3-Willow, 2-Grass, as 12-Gravel, classified water or WEVCLS##= Vegetation 5cm; every 11-Tree, transect W-E 1m 10-Moss, 9-Herb, 8-Lupine, 7-Duff, Rock, page. next Continued
392
606 7 0 7 0707162212 050505 0 5 9 7 9 012139169 9 1610160 070707 0 7 0125823426 060606 0 6 060606 0 6 060606 0 6 060606 0 6 293862109 3917158152815 4919 9 251241231171 323353343323 4 393423453423 6 221261261291 149991294 18 159899296881068 1881581249 129629389269 249299429729 153383083980 608638608598 0 6 15 9 8 9 3626969 11 155034834 24 15 WEVGH85 WEVCLS85 WEVGH90 WEVCLS90 WEVGH95 WEVCLS95 WEVGH100 WEVCLS100 27 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 PL OTID Appendix 1 (continued).
393