DIET OF THE CASCADES FROG (RANA CASCADAE) AS IT RELATES TO PREY

AVAILABILITY IN THE KLAMATH MOUNTAINS OF NORTHWEST

CALIFORNIA

By

Monty Daedalus Larson

A Thesis

Presented to

The Faculty of Humboldt State University

In Partial Fulfillment

Of the Requirements for the Degree

Masters of Science

In Natural Resources: Wildlife

May 2012

ABSTRACT

Diet of the Cascades Frog (Rana cascadae) as it relates to prey availability in the Klamath Mountains of Northwest California

Monty Larson

Frogs in the family Ranidae are considered generalist predators that consume prey as it is encountered in the environment. However, few studies have attempted to quantify the types and relative amounts of prey available to these frogs so a thorough understanding of their foraging ecology as it relates to prey availability is lacking. This study examined the diet of R. cascadae as it relates to prey availability in a Klamath

Mountain basin in northern California during their active season of 2007. Based on the analysis of 275 stomach samples, Rana cascadae consumed 3052 prey items from 110 invertebrate taxa confirming that this species is a generalist predator. However, an Index of Relative Importance indicated that five prey categories were most important in the diet: Acrididae, Aranae, Formicidae, insect larvae, and Tipulidae. Differences in diet were detected between sexes, life stages, and seasons. Adult females consumed more

Acrididae in the summer than males or Juveniles. Adult male and juvenile frogs showed selection for insect larvae and Tipulid flies during the summer. In the spring adult females and juveniles also selected Tipulid flies and adult males selected Elaterid beetles.

All life-stages and both sexes appeared to avoid very small prey (<4mm3). Shifts in prey use with changes in ontogeny were documented, with frogs consuming more large prey and less small prey as they grew.

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ACKNOWLEDGMENTS

This project was partially funded by a grant from the HSU Wildlife Graduate

Student Society. My study would not have been possible without the inspiration of my good friend Justin Garwood. Justin and I spent many nights sitting at the little blue table in the Alps discussing research possibilities and the ecological phenomena we were observing while carrying out Justin’s masters’ research. I could not have carried out this study without the support of my advisor, Dr. Hartwell H. Welsh, Jr. who provided encouragement and direction in the writing of my thesis as well as a Forest Service vehicle so that I could travel to and from the trailhead; a car being one of many resources

I lacked. I’d also like to thank Dr. Micheal A. Camann for providing me with all of the invertebrate sampling equipment I used to carry out this study and for hours of help teaching me to identify the invertebrates the frogs and I captured. I’d like to thank the fisheries group of Redwood Sciences Laboratory for allowing me to use their microscope; I’d still be measuring bugs if they hadn’t. I am tremendously indebted to the

Herpetology group of Redwood Sciences Laboratory. Clara, Garth, and Karen were always there to answer whatever questions I had or just to talk to. Finally I’d like to express the greatest appreciation, and deepest love to Kasey. She has been with me from the start of this project and has provided me with the encouragement, support, and love that carried me through.

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TABLE OF CONTENTS

Page

ABSTRACT ...... iii

ACKNOWLEDGMENTS ...... iv

LIST OF TABLES ...... vii

LIST OF FIGURES ...... viii

LIST OF APPENDICIES ...... x

INTRODUCTION...... 1

STUDY SITE ...... 4

MATERIALS AND METHODS ...... 8

Frog Surveys ...... 8 Gastric Lavage ...... 10 Invertebrate Sampling ...... 10 Invertebrate Identification...... 12 Statistical Analyses ...... 13 RESULTS ...... 19

Prey use ...... 19 Use versus Availability ...... 24 Female spring ...... 24 Female summer ...... 25 Female fall...... 28 Male spring ...... 31 Male summer ...... 31 Male Fall ...... 31 Juvenile spring ...... 36

v

Juvenile summer ...... 36 Juvenile fall ...... 36 Frog size ...... 41 DISCUSSION...... 46

LITERATURE CITED ...... 51

APPENDICIES ...... 57

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LIST OF TABLES

Table Page

Table 1. Comparison of prey category volumes of stomach samples collected from Rana cascadae by season, sex, and life-stage. Statistical comparisons were made using Multi Response Permutation Procedure. Significant comparisons are shaded. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 21

Table 2. Seasonally important prey categories in 275 stomach samples of Rana cascadae based on Indicator Species Analysis. Only prey categories with indicator values > 20 are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 23

Table 3. Comparison of proportions of prey items collected from Rana cascadae stomach samples to proportions of prey categories from both pitfall trap samples and sweep net samples using Multi-Response Permutation Procedure analysis. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 25

Table 4. Comparison of female Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 26

Table 5. Comparison of male Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 32

Table 6. Comparison of juvenile Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 37

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LIST OF FIGURES

Figure Page

Figure 2. Meadow patches where Rana cascadae stomach content and invertebrate sampling occurred in (A) Echo Lake sub-basin, and (B) Siligo sub-basin. Sampling patches are highlighted in red...... 6

Figure 3. Comparison of relative importance of prey categories collected from 275 Rana cascadae stomach samples. Only the 23 prey categories that occurred in greater than five percent of stomach samples are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 20

Figure 4. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 27

Figure 5. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 29

Figure 6. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 30

Figure 7. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 33

Figure 8. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 34

Figure 9. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 35

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Figure 10. Comparison of prey category indicator values of stomach samples collected from juvenile Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 38

Figure 11. Comparison of prey category indicator values of stomach samples collected from juvenile Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 39

Figure 12. Comparison of prey category indicator values of stomach samples collected from juvenile R. cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 40

Figure 13. Correlation of Rana cascadae mass and the proportion of Acrididae found in stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 43

Figure 14. Correlation of Rana cascadae mass to volume of the largest prey items in stomach samples. The study was conducted in 2007 in the Upper Deep Creek basin Trinity Alps Wilderness, California...... 44

Figure 15. Correlation of Rana cascadae mass to total prey volume in the stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 45

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LIST OF APPENDICIES

Page

Appendix A. Summary of prey items from Rana cascadae stomach samples collected from 11 July to 10 October 2005 in the upper Deep Creek Basin, Trinity Alps Wilderness...... 57

Appendix B. Comparisons of Rana cascadae stomach samples by census period using Multi Response Permutation Procedure analysis. Significance was established at α = 0.10 and corrected with a Bonferroni adjustment for 28 pair-wise comparisons resulting in α = 0.00357. Significant comparisons are shaded. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 58

Appendix C. Prey items identified from 275stomach samples of Rana cascadae collected from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 59

Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 64

Appendix E. Correlations of Rana cascadae mass to proportion of a prey category in a stomach sample: A. Aranae, B. Formicidae, C. insect larvae, D. Tipulidae. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 69

Appendix F. Correlations of Rana cascadae mass to proportion of a prey category in a stomach sample: A. Apididae, B. Chironomidae, C. Cicadellidae. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 70

Appendix G. Correlations of Rana cascadae mass to: A. total prey volume in spring stomach samples; B. total prey volume in summer stomach samples; C. total prey volume in fall stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California...... 71

x

INTRODUCTION

Many amphibian species in the western United States have experienced recent population declines (Lanoo 2005), and declines of the Cascades Frog (Rana cascadae,

Slater 1939) have been documented throughout its range in California (Fellers and Drost

1993, Welsh et al. 2006, Fellers et al. 2008). As a result of these declines, R. cascadae has been listed as a species of special concern in California (Jennings and Hayes 1994) and is considered by the USDA Forest Service as a “sensitive” species (USDA Forest

Service 1998). Several factors have been proposed as responsible for the decline of R. cascadae including introduced trout, disease, pesticide drift, and synergistic effects of some or all these factors (Fellers et al. 2008). As R. cascadae declines continue, managers who oversee the remaining populations will require a thorough understanding of the basic ecology of these animals in order to reverse these declines. An aspect of R. cascadae ecology that has received little focus is their foraging ecology (Pearl and

Adams 2005).

Rana cascadae is a montane species distributed throughout the Cascade Mountain

Range of Washington, Oregon, and northern California, with disjunct populations occurring in the Olympic Mountains of Washington and the Klamath Mountains of northern California. In California R. cascadae is found above 1158 m elevation (Welsh et al. 2006, Fellers et al. 2008, K. Pope and M. Larson, unpublished data). As a montane frog, R. cascadae populations are subjected to the harsh extremes of high elevation environments, where their active season is subject to climate induced limits.

In the Klamath Mountains R. cascadae is typically active from mid-May to mid-

1 2 October, although this period can be significantly shorter at higher elevation sites or during years of exceptional snowfall as documented in the upper Deep Creek Basin of the

Trinity Alps (Garwood 2009). During this restricted activity period R. cascadae must breed and find enough food to accumulate the fat stores needed to survive seven or more months of inactivity. Rana cascadae is active diurnally, highly aquatic, and most often found near water (Olson 2005). Breeding in this species occurs once a year and begins almost immediately with the late winter or early spring thaw as portions of breeding areas become snow free (Sype 1975, Briggs 1976). Following reproduction in the Trinity Alps,

R. cascadae will typically relocate from breeding sites to different areas within the drainage basin where their primary activity for the remainder of the active season is to forage and replace spent energy stores in preparation for the next winter (Garwood 2009).

During this period R. cascadae use a wide range of available aquatic habitats including lakes, ephemeral ponds, streams, and most aquatic habitats in wet meadows with surface areas greater than 0.5 m2 and depths greater than 10 cm (Garwood and Welsh 2007).

Movements of R. cascadae from these active season foraging habitats to overwintering sites were also documented as frogs moved away from drying habitat patches to permanent water sources where hibernation occurs (Garwood 2009).

Garwood (2009) found that adult females and juveniles of R. cascadae were captured in stream (lotic) habitats in higher proportions than adult males during summer months. In a pilot study conducted in 2005, I found that frogs captured in lotic habitats had larger stomach samples by dry weight than frogs captured in lentic (pond) habitats.

Additionally, female frogs were found to eat higher proportions of orthopterans than males and juveniles (Appendix A). Larger prey items can provide more calories per

3 foraging effort allowing female frogs to accumulate the greater energy stores required for them to become gravid and reproduce the following year. Thus, it appears that prey distribution and availability across the landscape may be an important component of sex and stage-specific foraging strategy, affecting growth rates, and probably over-winter survival.

Studies documenting R. cascadae diet are mostly absent from the scientific literature. Two papers report predation on larvae and newly metamorphosed Pseudacris regilla and Rana cascadae (Briggs and Storm 1970, Rombaugh 2003). My study was intended to provide a better understanding of R. cascadae diet and also further the understanding of the seasonal resource needs of this species in a relatively pristine area.

My specific objectives were to determine: (1) if R. cascadae consumes particular invertebrate taxa more than others, and to determine if prey use differs by sex, life-stage, and season; (2) if the prey consumed by each sex and life-stage of R. cascadae within a season differs from that which is available in the environment; and (3) if frog size (mass) correlates with the proportion of a prey category, as well as minimum and maximum prey item volume, and the total volume of a stomach sample.

STUDY SITE

The upper Deep Creek Basin is located in the southeastern portion of the Trinity

Alps Wilderness in Northern California (Figure 1). The climate of the region is

Mediterranean with cool wet winters and warm dry summers. Most precipitation falls as snow from November to May with summer precipitation coming from occasional thunderstorms. The year this study was conducted (2007) regional snowpack as measured at the Red Rock Mountain snow station (~10 km north, elevation 2042 m) was

38% of average (California Dept. of Water Resources, 2011). Air temperature from June

1 to September 21 averaged 14.4oC and ranged from -3.3 oC to 31.1 oC. Average daily air temperature during the active period (average air temperature from 1000h to 1700h 1

June to 21 September) was 19.2 oC and ranged from 1.6 oC to 29.2 oC. Five precipitation events occurred during the field season falling either as rain or snow.

The flora of the Trinity Alps is diverse and well documented (Ferlatte 1974).

Within the upper Deep Creek Basin there are three major plant communities: sub-alpine meadow, sub-alpine forest, and montane chaparral. The composition of these communities is driven by the ultramafic bedrock which when weathered creates soils toxic to most plants. Consequently, the area has sparse forests composed of tolerant plants many unique to the Klamath Mountains (Ferlatte 1974). This highly fractured bedrock also creates many unique aquatic features especially springs which provide the foundation for the large meadow complexes in the upper Deep Creek Basin. Study sites consisted of nine patches within this meadow complex and a 125 meter portion of the shoreline of Echo Lake (Figure 2). Three of the meadow patches were along streams

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Figure 1. Location of the study area in the southeastern portion of the Trinity Alps Wilderness, Trinity County, California. Watershed boundary of the upper Deep Creek Basin is shown by the black dotted line.

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Figure 1. Meadow patches where Rana cascadae stomach content and invertebrate sampling occurred in (A) Echo Lake sub-basin, and (B) Siligo sub-basin. Sampling patches are highlighted in red.

7 (Lower Siligo Meadow, Lower Van Matre Meadow, and Middle Siligo Meadow), three were in wet meadows with large spring fed ponds (Bob’s Meadow, Deep Creek Meadow

‘C’, and Penthouse Ponds), and three were in higher slope meadows with seasonal springs (Cascade Meadow, Deep Creek Meadow ‘I’, and South Siligo Meadow) that typically went dry by the end of the frogs’ active season (J. Garwood, unpublished data).

MATERIALS AND METHODS

Frog Surveys

I conducted pilot studies in 2005-6 to develop and test the methods used in this study (described below). The field sampling reported here took place in 2007. Each sampling effort was conducted over an eight to ten day period referred to hereafter as a census. Census one began 1 June and ended 10 June; a cold rain storm forced survey efforts to be abandoned from 6 June to 8 June. Dates for the remaining censuses were as follows: census two, 15 June – 22 June; census three, 1 July – 8 July; census four, 15 July

– 22 July; census five, 31 July – 7 August; census six, 14 August - 21 August; census seven, 30 August – 6 September; census eight, 13 September – 21 September.

Visual encounter surveys (Crump and Scot 1994) were conducted for R. cascadae by walking the shoreline of all water bodies within each patch (Figure 3). Surveys were conducted between 1000h and 1700h when the air was warm and the wind was calm.

Inclement weather was avoided as much as possible, however, several storms occurred over the summer restricting survey efforts to days when it was not raining or snowing regardless of whether or not the temperature and wind conditions were optimal for surveying. Only post-metamorphic frogs larger than 30 mm were captured. The capture protocol was adapted from (Garwood 2009); captured frogs were placed into numbered pint-sized plastic sandwich bags with a small amount of water. A numbered pin flag was placed at each capture location and frogs were returned to that location once they were processed. Capture locations were recorded on geo-referenced maps (accuracy ±3 m)

8 9 and UTMs were later retrieved in a GIS. All captured frogs were weighed to the nearest gram with a 60 g Pesola spring scale (accuracy ± 3%). Snout-urostyle lengths (SUL) were measured to the nearest mm using metric dial calipers (accuracy ± 1 mm).

Measurements of SUL were standardized by “maxing out” SUL lengths of individual frogs. This was achieved by placing frogs on a flat surface and applying gentle lateral and vertical pressure on the animal when measuring. This method of measurement minimized SUL length variation by not allowing frogs to contract during measurement.

To identify individual frogs, those larger than 36 mm were marked with passive integrated transponder (PIT) tags (TX1400L, Biomark Inc., Boise, Idaho, USA). PIT- tags were inserted under the frog’s skin by making a small ‘v’ shaped incision using stainless steel dissecting scissors sanitized in 70% propanol (Pope and Mathews 2001).

Incisions were made on the dorsal surface of the frog between the dorsal lateral folds anterior to the sacral hump and pit-tags were moved by hand down the frogs back posterior to the sacral hump. Frogs less than 36mm were marked with visual implant elastomer (Northwest Marine Technologies Shaw Island, WA) when these small frogs had gastric lavage performed on them; each received a mark unique to the census period when it was captured. Unique marks were achieved by using different colors and placing marks in more than one leg. Visual implant elastomer tags have been shown to have no effect on amphibian survival (Nauwelaerts et al. 2000, Bailey 2004) and they are preferable to toe clipping which has been shown to negatively affect return rates

(McCarthy and Parris 2004). Frogs were marked to avoid stomach flushing the same animal two censuses in a row; frogs were stomach flushed a maximum of three times

10 over the summer to reduce the possible effects of multiple stomach sampling procedures on growth and fat accumulation.

Gastric Lavage

Gastric lavage was performed to obtain the stomach contents of frogs using a modification of the technique described by Legler and Sullivan (1979). One of two syringes was used to flush frog stomachs. A 30 ml syringe with 1 or 2 mm diameter catheter tubing was used for frogs from 30 mm to 65 mm SUL and a 100 ml syringe with

4 mm tubing was used on frogs greater than 65 mm SUL. The mouths of frogs were gently pried open using blunt flat forceps and catheter tubing was inserted into the stomach. Frogs were then held vertically with their head over a sieve. To prevent food contents being forced into the intestines I pressed on the lower abdomen with my thumb.

Usually this technique worked well with all stomach contents flushed on the first try. If contents did not flush on the first try I would repeat the lavage twice more and if I was not successful I discontinued flushing. On one occasion a frog had an exceptionally large bolus that I was able to palpate and then perform gastric lavage to ensure a complete stomach sample was obtained. Gastric lavage was performed on individual frogs at most once every 30 days. All stomach contents were placed into glass vials filled with 70% 2- propanol with labels containing PIT-tag number or elastomer mark number, a three letter site code, and the survey date.

Invertebrate Sampling

To sample prey available to R. cascadae I used two invertebrate collecting methods. To capture ground crawling invertebrates I deployed a single pitfall trap in

11 each patch. Traps were generally located in the middle of the ten patches and were placed 25 cm from aquatic habitat. Pitfall traps were made from 475 ml food containers with 1 cm diameter holes cut at 2 cm intervals around the top band of the container. A small hole (~15 cm deep) was dug to place the traps at ground level. A tray made by cutting the bottom 4 cm of another food container was placed inside the trap and was partially filled with 50% propylene glycol. Propylene glycol was chosen for its preservative quality as well as its resistance to evaporation. A fitted lid was placed over the top of the trap to prevent non-target small animals from entering. Pitfall traps were set at the beginning of each census period and were deployed for 8 days. Pitfall traps were pulled at the end of each census in the same order they were set to ensure traps had similar capture periods. Invertebrates captured in pitfall traps were sieved to separate the invertebrates from the propylene glycol. Invertebrates were then placed into glass vials filled with 70% 2-propanol and labeled with census number, date, and site identity. All propylene glycol was collected, filtered, and stored in a 1 L Nalgene bottle to redeploy on the next census. Shields made by cutting the upper 5 cm from food containers were placed inside the traps to cover the holes in the top band of a trap and prevent entry to the inactive traps.

To capture flying and foliage dwelling invertebrates I used a 50 cm diameter insect net with a 0.5 mm mesh size. I made 10 sweeps through the vegetation along the shoreline of aquatic habitats at a height of ~25 cm using a back and forth motion and ~1 m swings. Sweep net samples were taken on the day I conducted stomach sampling at a site. All captured invertebrates and plant material were placed into pint size freezer bags

12 with 50% propylene glycol and labeled with census date and site id. Sweep net samples were sorted at camp to separate invertebrates from plant material. Invertebrates were placed into glass vials containing 70% 2-propanol. All propylene glycol was filtered into a 1L Nalgene bottle and stored for reuse. Plant material and coffee filters soaked in propylene glycol were destroyed by burning in a campfire.

I collected prey availability samples at each of the ten sites during each census for a total of 80 sweep net samples and 79 pitfall trap samples. I could not place a pitfall trap at Echo Lake during the first census due to site inundation.

Preliminary analysis of invertebrate community data showed one patch, Bob’s

Meadow, was different from the others. Closer inspection of these data revealed that the differences were based on the overall lower abundances of invertebrates captured and not on a different invertebrate community. The lower invertebrate abundances encountered at Bob’s Meadow may have been in response to the plant community where availability samples were collected. In the portion of Bob’s Meadow (Figure 3) where availability samples were collected the vegetation consisted mostly of sparse Juncus sp., while the other patches were mostly denser Carex sp. I do not believe that these differences are a concern because availability samples were relativized prior to analysis.

Invertebrate Identification

All invertebrates obtained by gastric lavage, captured in pitfall traps, and in sweep net samples, were identified to the lowest taxonomic level possible; usually this was to family, but severely disarticulated prey and non-insect prey were identified to order, using a dichotomous key (Boror and Delong 2007). Questionable identifications were

13 confirmed by M. Camann (Humboldt State University). I measured length and width of most invertebrates using a dissecting microscope with an ocular micrometer with gradations equal to 0.2 mm (10X eyepiece and 10X objective set at one). Total length was measured from the anterior portion of the head to the posterior-most part of the abdomen. Width was measured as the distance from the dorsal-most portion of the thorax to the ventral-most portion and perpendicular to the length measurement. Where only one dimension of a prey item could be determined I used a linear regression of the length or width based on whole invertebrates from the same family collected in stomach or availability samples. Regressions of invertebrate length and weight were highly significant with all r2 values greater than 0.55 and generally greater 0.80. To approximate the volume of invertebrates I used the formula for a prolate spheroid where:

Volume =

Statistical Analyses

I analyzed all frog stomach samples for similarity of content by census period using a Multi Response Permutation Procedure (MRPP; Mielke 1984) analysis. This analysis allowed me to combined censuses based on the lack of significant differences as follows: census one and two are combined and hereafter referred to as spring, census three, four, five, and six are combined and referred to as summer, and census seven and eight are combined and referred to as fall (Appendix B).

To test my first objective that particular invertebrate taxa are consumed more than others, and that this prey use differed by season, life-stage, and sex, I analyzed the frog stomach samples in two ways. First I calculated an Index of Relative Importance (IRI;

14 Pinkas et al. 1971) to determine which prey categories were more frequently found in the overall diet of R. cascadae regardless of sex, life stage, or season. The Index of Relative

Importance is calculated as:

IRI = (% V + % N) * % F where % V is the total volume of a prey category in all stomach samples divided by the total volume of all prey items, % N is the total number of items in a prey category divided by the total number of all prey items, and % F is the total number of stomachs containing a prey category divided by the number of stomachs containing prey items.

The IRI balances prey item size and number of prey items with the frequency of occurrence of a prey category to determine its’ relative importance in an animal’s diet. In this analysis I define an important prey category as accounting for ≥10% of the values in the IRI analysis.

To examine the second component of my first objective, that prey use differs by season, sex, and life-stage, stomach content data were subset into sex and life stage categories in three seasons and analyzed using Multi-Response Permutation Procedure

(MRPP) to determine whether differences existed among the samples in each of these groupings. In the MRPP analysis I used volume (rather than the number) for each prey category because volume better represents the relative amount of each invertebrate taxon in each grouping. Multi-Response Permutation Procedure is a nonparametric procedure that tests the hypothesis of no difference between two or more groups similar to discriminant analysis and MANOVA, but MRPP avoids distributional assumptions

(McCune and Grace 2002). Multi-Response Permutation Procedure analysis is based on

15 the T test statistic which describes the relative separation between groups; as T becomes more negative the separation between groups increases. The chance-corrected within- group-agreement A is a measure of effect size and describes within group homogeneity compared to random chance. When A =1 all items within a group are identical. When A

= 0 heterogeneity within in groups equals that expected by chance. When A < 0 there is more within group heterogeneity than expected by chance. For all MRPP analysis I used the Sorensen distance measure. Significance of an MRPP analysis was determined after applying a Bonferoni correction for multiple comparisons (α = 0.10/18). In order to determine which prey comprised the differences detected between frog groups in the

MRPP analysis I used Indicator Species Analysis (ISA; Dufrene and Legendre 1997).

Indicator Species Analysis combines the proportional volume of each prey category in a group, and the proportional frequency of occurrence of that prey category by season, life- stage, and sex (McCune and Grace 2002). These two proportions are multiplied together and then multiplied by 100 to yield an indicator value (IV). Indicator Species Analysis determines whether or not certain prey categories are more frequently encountered in the seasonal diet by life-stage and sex. I established a threshold of an indicator value ≥20 and statistical significant as constituting an important part of the seasonal diet. An indicator value ≥20 requires that a prey category be both present in at least 20% of the samples in a group, with all the volume of that prey category occurring in that group.

This threshold can also be achieved by a prey category occurring in all samples from a group and comprising at least 20% of the prey category volume in that group. Any combination of values for occurrence and volume between these thresholds could also

16 yield an indicator value ≥20. I ran 4999 randomized Monte Carlo trials to evaluate the significance of indicator values. All MRPP and ISA were performed using PC-ord 5.10

(McCune and Mefford 2006).

The second objective I evaluated was that the prey consumed differed from that which was available in the environment. Prior to testing this objective I removed all prey categories that occurred in <5% of stomach samples. This reduced the number of prey categories to 23 for this analysis. I then performed an ISA on the availability samples to determine which sampling technique (pitfall trapping or sweep netting) more effectively sampled each of these 23 prey categories. Six prey categories were more effectively sampled with pitfall traps, 12 with sweep nets, and five were not favored by either method (Appendix D). I relativized all stomach samples, pitfall trap, and sweep net samples (availability data) by combining two values for each prey category in each of the samples. These values were calculated as (% V + % N)/2 where % V is the total volume of a prey category in a sample divided by the total volume of all prey items in that sample, and % N is the total number of items in a prey category divided by the total number of all prey items in the sample. I assumed that combining these two values would better represent both prey consumed and prey available to R. cascadae since the numerical proportion can be overwhelmed by abundant small prey and the volumetric proportion can be overwhelmed by a few large prey. Thirteen stomach samples were removed from this analysis because they did not contain any prey of the 23 prey categories that occurred in >5% of stomach samples.

17 To test my second objective, I compared stomach samples from each season by life-stage and sex with data from pitfall trap samples, sweep net samples, or both

(hereafter availability samples). I used MRPP to determine if differences existed between the stomach samples from each frog group and the availability samples; and I used ISA to determine which prey categories differed between stomach samples and availability samples. A prey category that had a statistically significant indicator value would either indicate prey consumed in greater proportion than available (prey selection or +) if the value is for a stomach sample, or prey that is consumed in lower proportion than available (prey avoidance or -) if the value is for an availability sample. For prey categories that are compared to both availability sampling methods the indicator values must be significant in both instances for that prey category to be considered selected or avoided.

To test my third objective, that frog size (mass) would correlate with the proportion of a prey category, minimum and maximum prey volume, and total volume of a stomach sample, I compared the proportion of a prey category in a stomach sample with frog mass using Spearman Rank correlation. I also used correlation analysis to compare the volume of the largest and smallest prey items in the stomachs, and total stomach volume, with frog mass. For this analysis I used all 275 stomach samples and all prey items found within regardless of the percentage of stomachs that contained that prey category (Appendix C). Correlation analysis was performed using NCSS software

(Hintze 2009). The purpose of this study was to describe general relationships in the food habits of R. cascadae which are poorly studied; therefore I am not concerned about

18 type II error, and set the significance level at α 0.10 for all the analyses (Shrader-

Frechette and McCoy 1993).

RESULTS

I had 562 unique captures of R. cascadae at ten study sites in the upper Deep

Creek Basin (Figure 3); 293 of these were appropriate for gastric lavage. Fifteen stomachs contained no prey items, and three frogs had stomach contents flush out of their intestinal tract, resulting in 275 stomach samples appropriate for content analysis. From these stomach samples I extracted 3052 unique prey items in 110 prey categories (102 insect families, insect larvae, Chilopoda, Collembola, Aranae, Acari, Bivalvia, Annelidia,

Anura) (Appendix C). One hundred ninety one prey items were disarticulated or highly digested and could only be identified to order. The average number of prey items per sample was 11.1 (SE = 0.6).

Prey use

The Index of Relative Importance revealed that five prey categories were most important in R. cascadae diet: Acrididae, Aranae, Formicidae, insect larvae, and

Tipulidae (Figure 3, Appendix C). Acrididae accounted for over 34% of the total prey volume. Aranae, Formicidae, insect larvae, and Tipulidae occurred in 58%, 45%, 62%, and 42% of stomach samples, respectively. These same prey categories accounted for

12%, 9%, 18%, and 9% of the total number of prey items, respectively.

Multi-Response Permutation Procedure analysis revealed significant differences in the summer diets of female, male, and juvenile frogs (Table 1). Differences were detected in the diet of females in spring and summer, in male diets in spring and fall, and in juvenile diets in all three seasons (Table 1). Important prey categories (indicator value

≥20) in the spring stomach samples of female frogs consisted of Aranae, Carabidae,

19

20 40

30

20

Perent Perent Relative Importance 10

0

Acari

Aranae

Geridae

Miridae

Apididae

Vespidae

Tipulidae

Acrididae

Carabidae Elateridae

Noctuidae

Leuctridae

Formicidae

Cantharidae

Nemouridae

Cicadellidae

insectlarvae

Coccinellidae

Staphylinidae

Anthomyiidae Chironomidae Limnephilidae Ichneumonidae

Figure 2. Comparison of relative importance of prey categories collected from 275 Rana cascadae stomach samples. Only the 23 prey categories that occurred in greater than five percent of stomach samples are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

21 Table 1. Comparison of prey category volumes of stomach samples collected from Rana cascadae by season, sex, and life-stage. Statistical comparisons were made using Multi Response Permutation Procedure. Significant comparisons are shaded. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Comparison T A p Spring female vs male -0.938 0.005 0.167 female vs juvenile -0.458 0.002 0.273 male vs juvenile -2.625 0.010 0.017 Summer female vs male -6.679 0.021 <0.001 female vs juvenile -15.536 0.034 <0.001 male vs juvenile -2.567 0.004 0.020 Fall female vs male -0.597 0.008 0.224 female vs juvenile -0.813 0.005 0.176 male vs juvenile -0.810 0.005 0.179

Female spring vs summer -5.741 0.033 <0.001 spring vs fall -0.959 0.009 0.162 summer vs fall 0.179 -0.001 0.467 Male spring vs summer -2.612 0.007 0.016 spring vs fall -3.695 0.022 0.003 summer vs fall -2.398 0.008 0.024 Juvenile spring vs summer -3.649 0.007 0.004 spring vs fall -6.637 0.021 <0.001 summer vs fall -8.555 0.015 <0.001

22 and Scarabaeidae (Table 2); Aranae were found in all 14 spring stomach samples,

Carabid beetles in seven, and Scarabid beetles were found in three samples. Acrididae were an important prey in summer stomach samples of female frogs, and were encountered in 20 of 37 summer stomach samples. Noctuid moths were an important prey in fall stomach samples of female frogs, occurring in two of five samples.

23 Table 2. Seasonally important prey categories in 275 stomach samples of Rana cascadae based on Indicator Species Analysis. Only prey categories with indicator values > 20 are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Observed IV from randomized Prey Category group Indicator groups Value (IV) Mean S.Dev p * Noctuidae female fall 36.5 5.9 4.20 <0.001 Acrididae female summer 28.8 7.3 3.95 0.004 Aranae female spring 31.5 13.6 4.09 0.005 Carabidae female spring 31.6 8.5 4.68 0.006 Scarabaeidae female spring 21.6 4.6 3.66 0.002

24 Use versus Availability

I collected 65,110 prey in 146 unique prey categories in sweep nets, mostly insects identified to family; and 7,600 prey in 111 unique categories in pitfall traps, also mostly insects identified to family (Appendix D). Of the 110 prey categories found in stomach samples, 94 (85.4%) were also captured in the availability samples, with 68

(61.8%) occurring in both types of sampling. Nine (8.2%) prey categories were encountered only in pitfall traps, and 17 (15.4%) were encountered only in sweep net samples. Thirty one prey items in stomachs in 16 prey categories (14.5%) were not captured in either availability sample.

I evaluated the objective that prey were consumed in proportion to their availability in nine iterations by grouping the stomach samples based on sex, life stage, and season. Many stomachs contained only prey items that were best sampled by one of the availability sampling techniques. For these stomach samples comparisons were only made with one availability sampling technique resulting in different sample sizes in some comparisons of consumed and available prey.

Female spring

Prey categories differed significantly between female spring stomach samples and both pitfall trap (N=10) and sweep net samples (N = 10) (Table 3) (stomach samples N =

14 and 13, respectively). The ISA determined that Tipulidae were encountered more in stomach samples than pitfall traps or sweep nets, while Acari, Acrididae, Aranae, and

Staphylinidae were detected more in pitfall traps, and Acrididae, Anthomyiidae,

Apididae, Chironomidae, and Cicadellidae were detected more in sweep nets, than in stomach samples (Table 4, Figure 4).

25 Table 3. Comparison of proportions of prey items collected from Rana cascadae stomach samples to proportions of prey categories from both pitfall trap samples and sweep net samples using Multi-Response Permutation Procedure analysis. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Comparison T A p Female Spring (stomach vs. pitfall) -3.347 0.057 0.007 Spring (stomach vs. sweep) -7.663 0.113 <0.001 Summer (stomach vs. pitfall) -7.980 0.058 <0.001 Summer (stomach vs. sweep) -20.023 0.149 <0.001 Fall (stomach vs. pitfall) -1.193 0.048 0.119 Fall (stomach vs. sweep) -3.224 0.131 0.006 Male Spring (stomach vs. pitfall) -5.383 0.070 <0.001 Spring (stomach vs. sweep) -6.387 0.074 <0.001 Summer (stomach vs. pitfall) -13.981 0.092 <0.001 Summer (stomach vs. sweep) -21.248 0.134 <0.001 Fall (stomach vs. pitfall) -1.552 0.054 0.078 Fall (stomach vs. sweep) -5.260 0.212 0.001 Juvenile Spring (stomach vs. pitfall) -4.559 0.046 0.003 Spring (stomach vs. sweep) -7.268 0.066 <0.001 Summer (stomach vs. pitfall) -18.946 0.081 <0.001 Summer (stomach vs. sweep) -26.001 0.109 <0.001 Fall (stomach vs. pitfall) -3.619 0.043 0.006 Fall (stomach vs. sweep) -4.302 0.058 0.002

26 Table 4. Comparison of female Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Observed IV from randomized Prey Category Prey Use Indicator groups Value (IV) Mean S.Dev p-value stomach vs. pitfall spring Acari avoided (-) 81.6 31.8 9.10 <0.001 Acrididae avoided (-) 30.0 14.9 6.45 0.058 Staphylinidae avoided (-) 72.4 28.8 8.54 0.001 summer Acari avoided (-) 79.1 21.7 5.38 <0.001 Aranae avoided (-) 76.1 39.7 5.36 <0.001 fall Aranae avoided (-) 87.8 52.1 16.72 0.050 stomach vs. sweep spring Acrididae avoided (-) 30.0 16.1 6.54 0.067 Anthomyiidae avoided (-) 60.0 25.7 9.10 0.001 Apididae avoided (-) 87.7 39.1 8.77 <0.001 Chironomidae avoided (-) 100.0 33.8 9.87 <0.001 Cicadellidae avoided (-) 100.0 33.8 9.96 <0.001 Tipulidae selected (+) 55.6 40.0 9.70 0.082 summer Apididae avoided (-) 94.1 29.7 5.34 <0.001 Chironomidae avoided (-) 93.9 25.3 5.94 <0.001 Cicadellidae avoided (-) 87.2 28.8 5.92 <0.001 Miridae avoided (-) 60.9 26.2 5.96 <0.001 fall Apididae avoided (-) 100.0 40.1 17.37 0.017 Chironomidae avoided (-) 100.0 38.4 18.72 0.017 Cicadellidae avoided (-) 92.0 46.6 17.60 0.032

27

Figure 3. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

28 Female summer

Prey categories differed significantly between female summer stomach samples and both pitfall trap (N = 21) and sweep net samples (N = 21) (Table 3) (stomach samples N = 38 and 37, respectively). Indicator Species Analysis revealed that Acari and

Aranae were detected more in pitfall traps, and Apididae, Chironomidae, Cicadellidae,

Coccinellidae, and Miridae were detected more in sweep nets, then in stomach samples

(Table 4, Figure 5).

Female fall

Prey categories differed significantly between female fall stomach samples (N =

5) and both pitfall trap (N = 3) and sweep net samples (N = 3) (Table 3). Indicator

Species Analysis revealed that Aranae was detected in pitfall traps, and Apididae,

Chironomidae, and Cicadellidae were detected more in sweep nets then in the stomachs

(Table 4, Figure 6).

29

Figure 4. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

30

Figure 5. Comparison of prey category indicator values of stomach samples collected from female Rana cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

31 Male spring

Prey categories differed significantly between male spring stomach samples and both pitfall trap (N = 10) and sweep net samples (N = 11) (Table 3) (stomach samples N

= 22 and 18, respectively). The ISA determined that Elateridae was encountered more in stomach samples than pitfall traps or sweep nets, while Acari and Aranae were encountered more in pitfall traps, and Anthomyiidae, Apididae, Chironomidae, and

Cicadellidae were detected more in sweep nets, than in stomach samples (Table 5, Figure

7).

Male summer

Prey categories differed significantly between male summer stomach samples and both pitfall trap (N = 21) and sweep net samples (N = 21) (Table 3) (stomach samples N

= 43 and 39, respectively). The ISA determined that insect larvae and Tipulidae were encountered more in stomach samples than pitfall traps or sweep nets, while Acari,

Acrididae, and Aranae were detected more in pitfall traps, and Acrididae, Apididae,

Chironomidae, Cicadellidae, and Miridae were detected more in sweep nets, than in stomach samples (Table 5, Figure 8).

Male Fall

Prey categories differed significantly between male fall stomach samples and both pitfall trap (N = 5) and sweep net samples (N = 5) (Table 3) (stomach samples N = 13 and 8, respectively). Indicator Species Analysis determined that Acari and Aranae were detected more in pitfall traps, and Apididae, Chironomidae, and Cicadellidae were detected more in sweep nets, than in stomachs (Table 5, Figure 9).

32 Table 5. Comparison of male Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Observed IV from randomized Prey Category Prey Use Indicator groups Value (IV) Mean S.Dev p-value stomach vs pitfall spring Acari avoided (-) 74.8 22.8 7.38 <0.001 Aranae avoided (-) 65.2 40.3 7.45 0.007 Elateridae selected (+) 40.1 27.4 8.36 0.095 summer Acari avoided (-) 81.0 19.2 5.02 <0.001 Acrididae avoided (-) 24.2 17.1 4.57 0.078 Aranae avoided (-) 76.0 42.7 4.80 <0.001 larvae selected (+) 57.0 43.6 4.97 0.016 Staphylinidae avoided (-) 34.1 25.8 5.52 0.084 fall Acari avoided (-) 60.0 20.0 9.54 0.015 Aranae avoided (-) 68.0 44.5 11.70 0.045 stomach vs sweep spring Anthomyiidae avoided (-) 34.2 22.1 8.03 0.071 Apididae avoided (-) 81.1 41.0 8.03 <0.001 Chironomidae avoided (-) 92.8 32.9 8.72 <0.001 Cicadellidae avoided (-) 79.9 37.9 8.41 <0.001 Elateridae selected (+) 46.8 29.2 8.52 0.042 summer Acrididae avoided (-) 37.1 22.7 5.18 0.019 Apididae avoided (-) 82.3 33.0 5.20 <0.001 Chironomidae avoided (-) 83.8 28.5 5.67 <0.001 Cicadellidae avoided (-) 92.1 28.5 5.61 <0.001 Miridae avoided (-) 65.7 22.5 5.52 <0.001 Tipulidae selected (+) 52.9 36.6 6.05 0.020 fall Apididae avoided (-) 67.8 42.6 13.07 0.052 Chironomidae avoided (-) 100.0 33.7 12.52 0.001 Cicadellidae avoided (-) 100.0 34.1 12.45 0.001

33

Figure 6. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

34

Figure 7. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

35

Figure 8. Comparison of prey category indicator values of stomach samples collected from male Rana cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

36 Juvenile spring

Prey categories differed significantly between juvenile spring stomach samples and both pitfall trap (N = 14) and sweep net samples (N = 15) (Table 3) (stomach samples N = 28 and 25, respectively). Indicator Species Analysis revealed that Tipulidae was found more in stomach samples then in pitfall traps or sweep nets, while Acari and

Formicidae were detected more in pitfall traps, and Apididae, Chironomidae, and

Cicadellidae were detected more in sweep nets, than in stomach samples (Table 6, Figure

10).

Juvenile summer

Prey categories differed significantly between juvenile summer stomach samples and both pitfall trap (N = 30) and sweep net samples (N = 30) (Table 3) (stomach samples N = 74 and 64, respectively). Indicator Species Analysis revealed that insect larvae and Tipulidae were found more in stomach samples then in pitfall traps or sweep nets, while Acari, Acrididae, and Aranae were found more in pitfall traps, and Acrididae,

Apididae, Chironomidae, Cicadellidae, Coccinellidae, and Miridae were detected more in sweep nets, than in stomach samples (Table 6, Figure 11).

Juvenile fall

Prey categories differed significantly between juvenile fall stomach samples and both pitfall trap (N = 12) and sweep net samples (N = 12) (Table 3) (stomach samples N

= 26 and 21, respectively). The ISA determined that Acari and Aranae were detected more in pitfall traps, and Apididae, Cicadellidae, and Miridae were detected more in sweep nets, than in stomach samples (Table 6, Figure 12).

37 Table 6. Comparison of juvenile Rana cascadae stomach samples in spring, summer, and fall with availability samples using Indicator Species Analysis. Only prey categories with significant Indicator Values are shown. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Observed IV from randomized Prey Category Prey Use Indicator groups Value (IV) Mean S.Dev p-value stomach vs pitfall Spring Acari avoided (-) 69.3 25.0 6.87 <0.001 Formicidae avoided (-) 59.0 27.4 6.88 0.001 Summer Acari avoided (-) 77.2 19.7 4.07 <0.001 Acrididae avoided (-) 26.5 15.8 3.59 0.015 Aranae avoided (-) 69.7 41.9 4.00 <0.001 Larvae selected (+) 63.5 46.1 3.49 <0.001 Fall Acari avoided (-) 60.3 24.1 7.03 <0.001 Aranae avoided (-) 70.0 41.1 6.68 <0.001 stomach vs sweep Spring Apididae avoided (-) 70.7 41.1 7.03 0.002 Chironomidae avoided (-) 79.8 32.5 7.27 <0.001 Cicadellidae avoided (-) 82.9 31.7 7.42 <0.001 Tipulidae selected (+) 46.8 33.1 6.55 0.039 Summer Acrididae avoided (-) 32.4 20.2 4.08 0.015 Apididae avoided (-) 91.9 28.4 4.35 <0.001 Chironomidae avoided (-) 83.6 23.5 4.56 <0.001 Cicadellidae avoided (-) 73.4 29.0 4.60 <0.001 Coccinellidae avoided (-) 27.1 19.4 4.69 0.073 Miridae avoided (-) 59.6 22.9 5.09 <0.001 Tipulidae selected (+) 57.4 37.9 4.83 0.002 Fall Apididae avoided (-) 62.7 43.3 6.92 0.014 Cicadellidae avoided (-) 59.8 37.5 7.07 0.009 Miridae avoided (-) 33.3 12.8 5.57 0.010

38

Figure 9. Comparison of prey category indicator values of stomach samples collected from juvenile Rana cascadae in the spring with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

39

Figure 10. Comparison of prey category indicator values of stomach samples collected from juvenile Rana cascadae in the summer with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

40

Figure 11. Comparison of prey category indicator values of stomach samples collected from juvenile R. cascadae in the fall with: A. pitfall trap samples, B. sweep net samples. * = significance. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

41 Frog size

My third objective, that frog mass would correlate with the proportion of a prey category, prey size, and total volume of a stomach sample, was examined first by testing the relationship between frog mass and the proportions of the five most important prey categories in a stomach sample. Of these five categories, only Acrididae showed a positive relationship with frog mass (r = 0.233 t = 3.967, p < 0.001) (Figure 13); Aranae,

Formicidae, insect larvae, and Tipulidae were not correlated with frog mass (Appendix

E). I then examined five additional families that were found in > 5% of frog stomachs.

These prey categories represent examples of both large prey items (Carabidae 12.28 mm3 and Vespidae 75.87 mm3) and small prey items (Apididae 0.22 mm3, Chironomidae 0.90 mm3, Cicadellidae 2.15 mm3). Carabidae (r = 0.190 t = 3.192, p = 0.002) and Vespidae

(r = 0.100 t = 1.667, p = 0.097) had weak positive correlations with frog mass, and

Apididae (r = -0.135 t = 2.259, p = 0.025), Chironomidae (r = -0.102 t = 1.696, p =

0.091), and Cicadellidae (r = -0.100 t = 1.660, p = 0.098) had weak negative correlations with frog mass (Appendix F).

Analysis of frog mass to the volume of the largest prey item in a stomach sample revealed a significant positive correlation (r = 0.413, t = 7.484, p < 0.001) (Figure 14).

The relationship between frog mass and the minimum prey volume also had a weak but significant positive relationship with mass (r = 0.107, t = 1.776, p = 0.077). Analysis of frog mass and total volume of prey items also revealed a significant positive correlation

(r = 0.464, t = 8.644, p < 0.001) (Figure 15). Further examination of this relationship by season confirmed that these significant positive correlations occurred across all three seasons (spring: r = 0.392, t = 3.379, p = 0.002; summer: r = 0.459, t = 6.491, p < 0.001;

42 fall r = 0.485, t = 3.847, p < 0.001) (Appendix G). There was no correlation between frog mass and the number of prey items in a stomach (r = 0.083, t = 1.386, p = 0.167).

43 1

0.8

0.6

0.4 Proportion of total prey totalof Proportion

0.2

0 0 10 20 30 40 Frog weight g

Figure 12. Correlation of Rana cascadae mass and the proportion of Acrididae found in stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

44 1200

1000

3 800

600

Prey Prey volume mm 400

200

0 0 10 20 30 40 Frog weight g

Figure 13. Correlation of Rana cascadae mass to volume of the largest prey items in stomach samples. The study was conducted in 2007 in the Upper Deep Creek basin Trinity Alps Wilderness, California.

45 1600

1400

1200

3

1000

800

600 Total prey prey volume mm Total 400

200

0 0 10 20 30 40 Frog mass g

Figure 14. Correlation of Rana cascadae mass to total prey volume in the stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

DISCUSSION

This study showed that Rana cascadae consumes a wide variety of prey. Of the

24 papers on ranid frog diet I reviewed, my study showed the highest diversity reported for prey identified mostly to the family level. While Whitaker et al. (1983) sampled the stomachs of 206 Columbia spotted frogs (Rana lutiventris) and identified 58 families of insects and 25 other prey categories (mostly order), here I identified over 100 families of insects in the stomachs of juvenile and adult R. cascadae.

While Rana cascadae can consume a wide variety of prey, I found their diet was dominated by a few prey categories (Acrididae, Aranae, Formicidae, insect larvae, and

Tipulidae). These same prey categories have been found to be important in the diets of other ranid frogs (e.g., Hirai and Matsui 1999, Bull 2003). Acrididae, Aranae,

Formicidae, insect larvae, and Tipulidae are all terrestrial, and three are non-flying invertebrates. A similar mix of terrestrial and non-flying insects has been found in other ranid frog diet studies (Turner 1959, Heeden 1972, Whitaker 1983, Hirai and Matsui

1999, Bull 2003, Parker and Goldstein 2004, Yilmaz and Kutrup 2006). One notable exception was Finlay and Vredenburg (2007) who used stable isotope analysis to determine that the subalpine-dwelling Mountain yellow-legged frog (Rana muscosa) consumed mostly aquatic invertebrate prey in the Sierra Nevada of California.

Significant differences were detected in R. cascadae diet by season, life-stage, and sex, with five prey categories being dominant in the seasonal diet of female frogs.

Female frogs consumed five prey categories (Aranae, Acrididae, Carabidae, Noctuidae, and Scarabaeidae) significantly more by volume in a season than either male or juvenile

46 47 frogs. Differences in diet composition by sex has not been previously noted, however, in two studies, one of Rana tempoaria( Houston 1973) and the other of Rana ridibunda

(Yilmaz and Kutrup 2006) diets were observed to vary monthly. Furthermore Hirai and

Matsui (1999) found Rana nigromaculata diet differed among life-stages. In my study significant differences in diet among life-stages and sexes in the spring or fall was not detected. A seasonal difference in female and male diet was also not detected in several of my comparisons. My small sample sizes of female and male frogs in the spring and fall may have limited my ability to detect some dietary differences.

Garwood (2009) found that R. cascadae habitat use differed among sexes and across seasons. For example, he found that 94% of young of the previous year were located within 100 meters of a breeding site, while only 40% of adult females and 50% of adult males were located within 100 meters of breeding sites. Consequently, in this study

I expected that these differences in habitat would be reflected in their diet. However, the analysis of stomach contents revealed dietary differences among seasons, but no significant differences were noted among habitat patches. The greatest differences in diet appeared to be driven by the life history requirements of the different frog groups (i.e. growth, reproduction), and not their habitat associations. The reasons for seasonal changes in habitat use by R. cascadae was beyond the scope of this study, however, considering that prey availability is similar among patches, other explanations should be considered in the future. As prey appears not to be limiting at this location, aspects such as predator avoidance, density dependence, and seasonal habitat changes may instead drive seasonal habitat distributions.

48 Comparing the prey consumed to the prey available revealed that R. cascadae did select certain prey over others. Two of the five most important prey categories in the general R. cascadae diet were consumed in greater proportion than available, even though other prey were numerically more abundant at the time. Tipulid flies, insect larvae, and Elaterid beetles appeared to be selected by a frog group in at least one season.

In addition to this prey selection, evidence of prey avoidance was observed. Of the 23 prey categories where available and consumed prey were compared, eight were considered small (mean volume < 4mm3); six of these eight were avoided by a frog group in at least one season. Small prey accounted for 48 of the 55 (87%) comparisons where prey avoidance was observed. With several additional observations of prey avoidance, frogs appeared to be avoiding more chitinous (4 of 55comparisons) or very large prey

(mean volume > 20mm3; 3 of 55 comparisons). In a study of the diet of the salamander

Plethodon cinereus Jaeger and Barnard (1981) found that prey with a more chitinous exoskeleton took longer to digest. Further, Diaz and Carrascal (1993) found that handling time for the lizard Psammodromus algirus increased exponentially with prey length.

The great imbalance between the number of occurrences of prey selection and prey avoidance is a result of several factors. In circumstances of prey avoidance, the avoidance was very strong, while prey selection was weaker and spread among several prey categories. The prey categories that were avoided by the frogs were captured very frequently in the availability samples (usually in more than 80% of the samples), while few prey categories were encountered in frog stomachs with that frequency. For a prey

49 category to be determined as selected by a frog group it had to be both proportionally more abundant in stomach samples than in the availability samples, and occur more frequently in the stomachs than in availability samples. This was a difficult threshold to achieve.

Most studies of ranid frog diet portray them as opportunists that eat prey as it is encountered in the environment. The spatial dimensions of the foraging niche where the frogs operate are difficult to sample thoroughly, and most diet studies are not able to include information on prey availability. Bull (2003) attempted to quantify prey use versus availability for Rana lutiventris, but the methods of availability sampling did not detect a sizable proportion of prey the frogs were consuming. In that study, 52% and

22% of taxa found in stomach contents were represented on sticky traps and in dip net samples, respectively. Of the remaining 26% of taxa found in stomachs, but not collected in availability sampling, were several groups which were heavily consumed. Hirai and

Matsui (2001) and Yalmaz and Kutrup (2006) used sweep net sampling to compare available prey to consumed prey. However, both studies could only compare frog diet with those invertebrates captured in the sweep nets, limiting the inferences that could be made on the data. In contrast, the availability sampling conducted in this study accounted for 85.4% of the prey categories encountered in stomach samples, indicating that availability sampling was highly effective. Furthermore, prey categories not represented in availability samples were not important in the overall frog diet, accounting for just 1.1 percent of the total prey items and 6.8% of the total volume. Utilizing use versus availability information has shown that R. cascadae can exhibit plasticity in feeding

50 events, behaving as a generalist or selecting certain prey depending on season, sex, and life-stage. This study suggests that availability of prey is an important component to understanding animal diets, including those of this montane ranid frog.

Evidence of ontogenetic shifts in diet were detected in this study. As frogs grew, the proportion of larger prey items increased. This was expected as gape width and strike ranges increase with age. Larger frogs were also shown to consume a larger volume of prey. Interestingly, there was no correlation between frog weight and number of prey items in a stomach. However, this result wasn’t surprising as the literature has examples of positive, negative, and even a curvilinear relationship between frog size and prey number (Labanick 1976, Christian 1982, Hirai 2002.

Ontogentic shifts in the diets of other anurans have been well documented (e.g.,

Labanick 1976, Christian 1982, Donnelly 1991, Simon and Toft 1991, Lima and Moreira

1993, Lima 1998, Lima and Magnusson 1998, Hodgkison and Hero 2003, and Blackburn and Moreau 2006), including in some ranid frogs (Forstner et al 1998, Hirai and Matsui

1999, and Hirai 2002). These studies all indicated that as frogs get larger they consume a greater volume of prey and larger prey items.

My results support an aspect of ecological niche theory that predicts the partitioning of niche dimensions within a species based on sex and life stage requirements (e.g., Toft 1985). This research reaffirms the value of studying an organisms’ basic natural history as it may reveal complex relationships that were previously unknown (Greene 2005).

LITERATURE CITED

Anderson, A. M., D. A. Haukos, and J. T. Anderson. 1999. Diet composition of three anurans from the playa wetlands of northwest Texas. Copeia 1999 (2): 515-520.

Bailey, L. L. 2004. Evaluating elastomer marking and photo identification methods for terrestrial salamanders: marking effects and observer bias. Herpetological Review 35: 38-41.

Biaviati, G. M., H. C. Wiederhecker, and G. R. Colli. 2004. Diet of Epipedobates flavopictus (Anura:Dendrobatidae) in a neotropical savana. Journal of Herpetology 38 (4): 510-518.

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APPENDICIES

Appendix A. Summary of prey items from Rana cascadae stomach samples collected from 11 July to 10 October 2005 in the upper Deep Creek Basin, Trinity Alps Wilderness.

Prey Classification Female Male Juvenile (N = 16) (N = 35) (N = 9) Lentic Number (Weight g) Number (Weight g) Number (Weight g) Aranae 6 (0.0583) 16 (0.2782) 9 (0.0284) Coleoptera 7 (0.1458) 82 (0.5841) 17 (0.1495) Diptera 12 (0.0830) 22 (0.1013) 10 (0.0180) Hemiptera 12 (0.0872) 29 (0.0658) 4 (0.0133) Hymenoptera 37 (0.9181) 43 (0.6246) 6 (0.1267) Lepidoptera 4 (0.0760) 8 (0.4390) 1 (0.0046) Orthoptera 14 (1.2334) 4 (0.6276) 0 Tricoptera 13 (0.1481) 34 (0.5375) 6 (0.0940) Other 10 (0.4478) 30 (2.1238) 2 (0.0148)

(N = 25) (N = 15) (N = 5) Lotic Number (Weight g) Number (Weight g) Number (Weight g) Aranae 8 (0.0372) 4 (0.0601) 4 (0.0184) Coleoptera 16 (0.1641) 19 (0.3214) 13 (0.0284) Diptera 11 (0.0551) 19 (0.0954) 9 (0.0631) Hemiptera 3 (0.0101) 3 (0.0049) 0 Hymenoptera 22 (0.6154) 10 (0.3355) 3 (0.0326) Lepidoptera 21 (1.2722) 4 (0.2404) 10 (0.4699) Orthoptera 25 (3.4147) 7 (1.2576) 1 (0.0709) Tricoptera 12 (0.1689) 9 (0.2896) 4 (0.0103) Other 17 (0.5732) 13 (0.2862) 5 (0.0688)

57 58 Appendix B. Comparisons of Rana cascadae stomach samples by census period using Multi Response Permutation Procedure analysis. Significance was established at α = 0.10 and corrected with a Bonferroni adjustment for 28 pair-wise comparisons resulting in α = 0.00357. Significant comparisons are shaded. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Census period T A p 1 vs. 2 -1.033 0.003 0.146 1 vs. 3 -7.836 0.022 <0.001 1 vs. 4 -3.107 0.009 0.008 1 vs. 5 -4.057 0.010 0.001 1 vs. 6 -4.327 0.010 0.001 1 vs. 7 -4.751 0.015 <0.001 1 vs. 8 -4.615 0.013 <0.001 2 vs. 3 -4.933 0.016 0.001 2 vs. 4 -2.430 0.008 0.023 2 vs. 5 -4.285 0.012 0.001 2 vs. 6 -4.062 0.011 0.002 2 vs. 7 -6.850 0.024 <0.001 2 vs. 8 -4.401 0.014 0.001 3 vs. 4 -1.324 0.005 0.100 3 vs. 5 -2.023 0.006 0.047 3 vs. 6 -5.825 0.016 <0.001 3 vs. 7 -9.069 0.032 <0.001 3 vs. 8 -6.427 0.021 <0.001 4 vs. 5 -0.146 <0.001 0.357 4 vs. 6 -0.325 <0.001 0.310 4 vs. 7 -5.065 0.019 <0.001 4 vs. 8 -2.378 0.008 0.026 5 vs. 6 -2.648 0.006 0.018 5 vs. 7 -5.146 0.016 <0.001 5 vs. 8 -2.604 0.008 0.016 6 vs. 7 -4.439 0.014 0.001 6 vs. 8 -1.068 0.003 0.139 7 vs. 8 0.469 -0.002 0.617

59 Appendix C. Prey items identified from 275stomach samples of Rana cascadae collected from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Number Volume Frequency Classification Total % Total % Total % % IRI Annelida Unidentified 1 0.03 3.77 0.01 1 0.36 <0.01 Arthropoda Arachnida Acari 28 0.92 3.05 0.01 14 5.09 0.09 Aranae 358 11.73 986.60 2.34 159 57.82 15.37 Chilopoda Unidentified 3 0.10 31.21 0.07 3 1.09 <0.01 Hexapoda Unidentified larvae 542 17.76 5529.05 13.10 170 61.82 36.06 Collembola Unidentified 11 0.36 1.39 0.00 7 2.55 0.02 Coleoptera Byrrhidae 3 0.10 31.43 0.07 3 1.09 <0.01 Cantharidae 27 0.88 315.96 0.75 15 5.45 0.17 Carabidae 62 2.03 593.02 1.41 47 17.09 1.11 Cerambycidae 2 0.07 134.70 0.32 2 0.73 <0.01 Chrysomelidae 6 0.20 47.06 0.11 6 2.18 0.01 Cicindelidae 3 0.10 69.97 0.17 3 1.09 <0.01 Coccinellidae 64 2.10 914.87 2.17 38 13.82 1.11 Curculionidae 1 0.03 7.18 0.02 1 0.36 <0.01 Dytiscidae 1 0.03 26.18 0.06 1 0.36 <0.01 Elateridae 42 1.38 558.03 1.32 32 11.64 0.59 Endomychidae 10 0.33 43.32 0.10 7 2.55 0.02 Hydraenidae 8 0.26 3.26 0.01 8 2.91 0.02 Hydrophilidae 5 0.16 53.58 0.13 5 1.82 0.01 Lathridiidae 2 0.07 0.48 0.00 2 0.73 <0.01 Melyridae 1 0.03 0.69 0.00 1 0.36 <0.01 Nitidulidae 1 0.03 7.57 0.02 1 0.36 <0.01 Scarabaeidae 9 0.29 162.32 0.38 6 2.18 0.03 Scirtidae 11 0.36 41.10 0.10 10 3.64 0.03 Scydmaenidae 1 0.03 4.90 0.01 1 0.36 <0.01 (continued)

60 Appendix C. Prey items identified from 275stomach samples of Rana cascadae collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Number Volume Frequency Classification Total % Total % Total % % IRI Staphylinidae 107 3.51 285.97 0.68 69 25.09 1.98 Silphidae 1 0.03 0.00 0.00 1 0.36 <0.01 Tenebrionidae 3 0.10 140.70 0.33 2 0.73 <0.01 Unidentified 19 0.62 22.00 0.05 13 4.73 0.06 Diptera Agromyzidae 5 0.16 5.17 0.01 4 1.45 <0.01 Anthomyiidae 30 0.98 284.59 0.67 24 8.73 0.27 Asilidae 13 0.43 1025.43 2.43 8 2.91 0.16 Bombyliidae 3 0.10 111.68 0.26 3 1.09 <0.01 Calliphoridae 5 0.16 159.37 0.38 5 1.82 0.02 Ceratopogonidae 3 0.10 0.79 0.00 3 1.09 <0.01 Chironomidae 33 1.08 25.24 0.06 23 8.36 0.18 Chloropidae 6 0.20 7.91 0.02 6 2.18 <0.01 Clusiidae 1 0.03 8.99 0.02 1 0.36 <0.01 Dolichopodidae 5 0.16 23.41 0.06 5 1.82 <0.01 Drosophilidae 3 0.10 5.30 0.01 3 1.09 <0.01 Empididae 10 0.33 56.22 0.13 9 3.27 0.03 Ephydridae 15 0.49 14.13 0.03 12 4.36 0.04 Fanniidae 5 0.16 8.21 0.02 5 1.82 <0.01 Lonchopteridae 4 0.13 3.04 0.01 4 1.45 <0.01 Muscidae 10 0.33 76.26 0.18 8 2.91 0.03 Mycetophilidae 5 0.16 10.28 0.02 4 1.45 <0.01 Phoridae 1 0.03 0.13 0.00 1 0.36 <0.01 Piophilidae 1 0.03 3.39 0.01 1 0.36 <0.01 Platypodidae 1 0.03 3.17 0.01 1 0.36 <0.01 Psychodidae 4 0.13 0.20 0.00 3 1.09 <0.01 Psyllidae 1 0.03 4.96 0.01 1 0.36 <0.01 Sarcophagidae 1 0.03 78.31 0.19 1 0.36 <0.01 Scathophagidae 4 0.13 70.64 0.17 4 1.45 <0.01 Sciaridae 2 0.07 0.34 0.00 2 0.73 <0.01 Sepsidae 1 0.03 0.00 0.00 1 0.36 <0.01 Sphaeroceridae 1 0.03 2.22 0.01 1 0.36 <0.01 Syrphidae 17 0.56 140.76 0.33 12 4.36 0.01

61 Appendix C. Prey items identified from 275stomach samples of Rana cascadae collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Number Volume Frequency Classification Total % Total % Total % % IRI Tachinidae 4 0.13 163.21 0.39 3 1.09 0.07 Tipulidae 276 9.04 2016.10 4.78 116 42.18 11.02 Unidentified 37 1.21 302.83 0.72 25 9.09 0.33 Ephemeroptera Leptophlebiidae 3 0.10 32.56 0.08 2 0.73 <0.01 Unidentified 32 1.05 265.02 0.63 13 4.73 Hemiptera Apididae 196 6.42 38.43 0.09 70 25.45 3.13 Cicadellidae 65 2.13 126.70 0.30 40 14.55 0.67 Coreidae 6 0.20 37.55 0.09 6 2.18 0.01 Delphacidae 3 0.10 1.07 0.00 3 1.09 <0.01 Geocoridae 1 0.03 2.53 0.01 1 0.36 <0.01 Geridae 39 1.28 348.73 0.83 29 10.55 0.42 Hemerobiidae 1 0.03 3.23 0.01 1 0.36 <0.01 Membracidae 1 0.03 22.90 0.05 1 0.36 <0.01 Mesoveliidae 1 0.03 0.83 0.00 1 0.36 <0.01 Miridae 19 0.62 52.07 0.12 15 5.45 0.08 Notonectidae 1 0.03 71.85 0.17 1 0.36 <0.01 Pachygronthidae 3 0.10 7.22 0.02 2 0.73 <0.01 Raphidiidae 1 0.03 41.62 0.10 1 0.36 <0.01 Rhyparochromidae 2 0.07 0.93 0.00 2 0.73 <0.01 Saldidae 8 0.26 34.84 0.08 8 2.91 0.02 Scutelleridae 7 0.23 238.50 0.57 7 2.55 0.04 Thryeocoridae 1 0.03 4.31 0.01 1 0.36 <0.01 Unidentified 4 0.13 0.01 0.00 4 1.45 <0.01 Hymenoptera Apidae 1 0.03 20.00 0.05 1 0.36 <0.01 Braconidae 3 0.10 0.94 0.00 3 1.09 <0.01 Chrysididae 3 0.10 17.93 0.04 3 1.09 <0.01 Encrytidae 5 0.16 0.45 0.00 5 1.82 <0.01 Eulophidae 2 0.07 0.05 0.00 2 0.73 <0.01 Eurytomidae 2 0.07 0.54 0.00 2 0.73 <0.01 Formicidae 279 9.14 1368.35 3.24 124 45.09 10.55

62 Appendix C. Prey items identified from 275stomach samples of Rana cascadae collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Number Volume Frequency Classification Total % Total % Total % % IRI Halictidae 3 0.10 22.12 0.05 3 1.09 <0.01 Ichneumonidae 33 1.08 234.11 0.55 28 10.18 0.32 Proctotrupidae 2 0.07 0.94 0.00 1 0.36 <0.01 Pteromalidae 2 0.07 0.23 0.00 2 0.73 <0.01 Scelionidae 1 0.03 0.05 0.00 1 0.36 <0.01 Sphecidae 2 0.07 78.63 0.19 2 0.73 <0.01 Tenthredinidae 6 0.20 32.22 0.08 5 1.82 <0.01 Vespidae 36 1.18 2427.99 5.75 27 9.82 1.29 Unidentified 9 0.29 36.28 0.09 9 3.27 0.02 Lepidoptera Noctuidae 15 0.49 828.96 1.96 14 5.09 0.24 Unidentified 15 0.49 1026.17 2.43 13 4.73 0.26 Neuroptera Nemouridae 19 0.62 86.62 0.21 14 5.09 0.08 Sialidae 19 0.62 254.84 0.60 7 2.55 0.06 Unidentified 1 0.03 50.36 0.12 1 0.36 <0.01 Odonata Aeshnidae 2 0.07 1187.62 2.81 2 0.73 0.04 Corduliidae 1 0.03 74.40 0.18 1 0.36 <0.01 Libellulidae 1 0.03 135.55 0.32 1 0.36 <0.01 Orthoptera Acrididae 71 2.33 14440.88 34.22 46 16.73 11.55 Unidentified 5 0.16 311.25 0.74 5 1.82 0.03 Plecoptera Chloroperlidae 2 0.07 102.90 0.24 2 0.73 <0.01 Leuctridae 145 4.75 45.42 0.11 20 7.27 0.67 Perlidae 3 0.10 380.92 0.90 3 1.09 0.02 Perlodidae 1 0.03 34.38 0.08 1 0.36 <0.01 Unidentified 31 1.02 58.39 0.14 16 5.82 0.13 Thysanoptera Phlaeothripidae 8 0.26 0.28 0.00 5 1.82 <0.01 Thrypidae 1 0.03 0.03 0.00 1 0.36 <0.01 Tricoptera

63 Appendix C. Prey items identified from 275stomach samples of Rana cascadae collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Number Volume Frequency Classification Total % Total % Total % % IRI Lepidostomatidae 1 0.03 26.60 0.06 1 0.36 <0.01 Limnephilidae 39 1.28 1417.43 3.36 21 7.64 0.67 Philopotamidae 3 0.10 28.55 0.07 3 1.09 <0.01 Rhyacophilidae 6 0.20 81.06 0.19 5 1.82 0.01 Unidentified 36 1.18 717.88 1.70 26 9.45 0.52 Chordata Amphibia Anura Hylidae 2 0.07 250.40 0.59 2 0.73 <0.01 Unidentified 2 0.07 431.38 1.02 2 0.73 <0.01 Mollusca Bivalvia 1 0.03 25.09 0.06 1 0.36 <0.01

64 Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

Encountered in Classification Pitfall trap Sweep net Stomach sample? Arthropoda Arachnida Acaria 849 86 yes Aranaea 1888 1065 yes Hexapoda Unidentified larvaea 287 420 yes Unidentified 2 5 Collembola Unidentified 427 62 yes Coleoptera Alleculidae 0 1 no Anobiidae 17 3 no Anthribidae 0 3 no Byrrhidae 1 5 yes Artematopidae 0 8 no Cantharidaea,b 8 18 yes Carabidaea 80 2 yes Chrysomelidae 26 102 yes Cicindelidae 1 0 yes Cleridae 0 4 no Coccinellidaeb 27 134 yes Curculionidae 3 4 yes Dytiscidae 1 0 yes Elateridaea,b 5 14 yes Endomychidae 23 14 yes Hydraenidae 0 1 yes Hydrophilidae 49 1 yes Lathridiidae 28 43 yes Leiodidae 39 9 no Melyridae 0 1 yes Nitidulidae 1 1 yes Noteridae 4 0 no Phalarcridae 0 4 no Phengodidae 23 12 no Pselaphidae 3 0 no Psephenidae 8 0 no Pteronarcyidae 0 17 no (continued)

65 Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Encountered in Classification Pitfall trap Sweep net Stomach sample? Ptiliidae 3 1 no Scarabaeidae 8 0 yes Scydmaenidae 2 0 yes Silphidae 31 4 yes Staphylinidaea 206 20 yes Tenebrionidae 0 5 yes Diptera Agromyzidae 3 85 yes Anthomyiidaeb 50 117 yes Anthomyzidae 2 47 no Asilidae 0 6 yes Asteiidae 0 1 no Calliphoridae 4 20 yes Cecidomyiidae 23 55 no Ceratopogonidae 15 447 yes Chamaemyiidae 0 110 no Chironomidaeb 161 4202 yes Chloropidae 279 1652 yes Clusiidae 0 7 yes Culicidae 0 1 no Curtonotidae 0 1 no Dolichopodidae 0 101 yes Drosophilidae 12 44 yes Empididae 6 59 yes Ephydridae 51 201 yes Fanniidae 3 676 yes Heleomyzidae 0 11 no Lauxaniidae 7 125 no Lonchaeidae 0 1 no Lonchopteridae 3 434 yes Micropezidae 21 20 no Muscidae 16 167 yes Mycetophilidae 7 16 yes Opomyzidae 0 2 no Phoridae 49 43 yes Pipunculidae 2 22 no Piophilidae 1 24 yes Platypezidae 0 1 no

66 Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Encountered in Classification Pitfall trap Sweep net Stomach sample? Platystomatidae 0 1 no Psilidae 3 1 no Psychodidae 36 22 yes Psyllidae 14 296 yes Sarcophagidae 2 2 yes Scathophagidae 4 47 yes Scatopsidae 44 15 no Sciaridae 69 1057 yes Sciomyzidae 0 74 no Sepsidae 13 253 yes Simuliidae 0 1 no Sphaeroceridae 107 19 yes Syrphidae 2 34 yes Tabanidae 2 0 no Tachinidae 5 7 yes Tephritidae 0 3 no Tipulidaeb 43 195 yes Tricoceridae 0 3 no Ephemeroptera Leptohyphidae 0 2 no Siphlonuridae 2 9 no Hemiptera Apididaeb 877 44074 yes Berytidae 1 2 no Cicadellidaeb 267 4540 yes Coreidae 4 136 yes Delphacidae 42 1133 yes Fulgoridae 0 1 no Geocoridae 19 3 yes Geridaea,b 3 1 yes Hebridae 0 1 no Largidae 1 2 no Lasiochilidae 0 9 no Lygaeidae 3 10 no Miridaeb 27 432 yes Notonectidae 1 0 yes Pachygronthidae 25 1 yes Pentatomidae 0 1 no

67 Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Encountered in Classification Pitfall trap Sweep net Stomach sample? Thryeocoridae 0 1 yes Rhyparochromidae 0 34 yes Saldidae 4 1 yes Scutelleridae 1 47 yes Hymenoptera Anaxyelidae 0 2 no Andrenidae 1 0 no Apidae 2 0 yes Aphelinidae 24 134 no Bethylidae 1 0 no Braconidae 18 132 yes Ceraphronidae 3 0 no Chalcididae 0 1 no Colletidae 0 4 no Diapriidae 7 7 no Encrytidae 5 32 yes Eulophidae 1 82 yes Eupelmidae 1 9 no Eurytomidae 1 9 yes Figitidae 4 27 no Formicidaea 489 90 yes Halictidae 3 18 yes Ichneumonidaeb 3 93 yes Mymaridae 13 26 no Ormyridae 0 1 no Perilampidae 0 4 no Platygastridae 0 1 no Pompilidae 1 2 no Proctotrupidae 7 5 yes Pteromalidae 4 75 yes Scelionidae 48 16 yes Sphecidae 4 0 yes Tenthredinidae 2 18 yes Tiphiidae 0 7 no Torymidae 0 2 no Vespidaea,b 26 16 yes Lepidoptera Lycaenidae 3 1 no

68 Appendix D. Invertebrates sampled by pitfall traps and sweep nets collect from 1 June 2007 to 21 September 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California (continued).

Encountered in Classification Pitfall trap Sweep net Stomach sample? Noctuidaeb 0 6 yes Neuroptera Chrysopidae 0 1 no Sialidae 3 0 yes Odonata Coenagrionidae 2 0 no Orthoptera Acrididaea,b 90 112 yes Tetrigidae 8 1 no Tettigonidae 3 1 no Plecoptera Chloroperlidae 0 17 yes Leuctridaeb 14 379 yes Nemouridaeb 0 44 yes Perlidae 0 1 yes Perlodidae 0 9 yes Thysanoptera Phlaeothripidae 4 38 yes Thrypidae 0 14 yes Tricoptera Hydropsychidae 1 0 no Leptoceridae 0 1 no Limnephilidaea,b 8 16 yes Philopotamidae 1 13 yes Rhyacophilidae 0 3 yes Amphibia Anura Hylidae 0 2 no aPitfall trap sample compared with stomach samples in analyses of use vs. available. bSweep net sample compared with stomach samples in analyses of use vs. available.

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Appendix E. Correlations of Rana cascadae mass to proportion of a prey category in a stomach sample: A. Aranae, B. Formicidae, C. insect larvae, D. Tipulidae. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

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Appendix F. Correlations of Rana cascadae mass to proportion of a prey category in a stomach sample: A. Apididae, B. Chironomidae, C. Cicadellidae. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.

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Appendix G. Correlations of Rana cascadae mass to: A. total prey volume in spring stomach samples; B. total prey volume in summer stomach samples; C. total prey volume in fall stomach samples. The study was conducted in 2007 in the upper Deep Creek Basin Trinity Alps Wilderness, California.