Great Basin Silverspot ( nokomis nokomis [W.H. Edwards]): A Technical Conservation Assessment

Prepared for the USDA Forest Service, Rocky Mountain Region, Conservation Project

April 25, 2007

Gerald Selby Ecological and GIS Services 1410 W. Euclid Ave. Indianola, IA 50125

Peer Review Administered by Society for Selby, G. (2007, April 25). Great Basin Silverspot Butterfly ( nokomis [W.H. Edwards]): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/greatbasinsilverspotbutterfly.pdf [date of access].

ACKNOWLEDGMENTS

This assessment was prepared for the Rocky Mountain Region of the USDA Forest Service under contract number 53-82X9-4-0074. I would like to express my appreciation to the USDA Forest Service staff with whom I worked on the project: Richard Vacirca reviewed earlier drafts, Gary Patton provided valuable general oversight for the project and suggested improvements for the final draft, John Sidle reviewed the final draft, Nancy McDonald provided final editorial review of the pre-publication manuscript, and Kimberly Nguyen prepared the manuscript for Web publication. The entire staff, including Richard Braun, the contracting officer, provided the flexibility and contract extensions needed to bring this assessment to final publication. Two anonymous reviewers also provided valuable feedback. Their careful review and editorial input helped to improve the quality of the final product greatly. I would also like to express my appreciation to Natural Heritage Program personnel and other experts (professional and amateur) that took time from their busy schedules to provide information and data needed to complete this assessment.

AUTHOR’S BIOGRAPHY

Gerald Selby developed an interest in at an early age while growing up in Pakistan. He received a B.S. in Biology from Sterling College in Kansas in 1976, and a M.S. in Biology (Ecology and Systematics emphasis) from the University of Michigan in 1979. His interest in butterflies was rekindled through contact with Dr. W.H. Wagner (Pteridologist and butterfly enthusiast), and after completing his M.S., he had the opportunity to do additional butterfly collecting in Pakistan during an extended visit. From 1980 to 1987 he worked for the Clinton County Conservation Board in eastern Iowa, and during that time, an exposure to prairie ecology and issues of prairie management gave purposeful direction to what had been a youthful hobby. A work accident left him with paralysis in his right arm, so he entered a Ph.D. program at Iowa State University in 1987, where his dissertation research was focused on the ecology and management of prairie butterflies in southwestern Minnesota. He worked as the Director of Science and Stewardship at The Nature Conservancy in Iowa from 1993 to 2002, and he has been self-employed as an ecological consultant since 2002. Gerald has been actively involved in prairie butterfly surveys and research in Iowa and Minnesota since 1988.

COVER PHOTO CREDIT

Great Basin silverspot butterfly Speyeria ( nokomis nokomis) male (left) and female (right). Photographs © Nearctica.com, Inc. 2000 (used with permission).

2 3 SUMMARY OF KEY COMPONENTS FOR CONSERVATION OF THE GREAT BASIN SILVERSPOT BUTTERFLY

Status

The Great Basin silverspot butterfly Speyeria( nokomis nokomis) has a fairly restricted distribution in eastern Utah, western , northern New Mexico, and northeastern Arizona. The Nokomis fritillary species (S. nokomis) has been assigned a Global Heritage Status Rank of vulnerable (G3), and its National Heritage Status Rank for United States populations is also vunerable (N3). Global and National Heritage Status Ranks for the Great Basin silverspot butterfly subspecies are both critically imperiled (T1, N1). The rationale for the species’ G3 ranking cites its very localized distribution in wet places associated with generally arid range, and increasing isolation and disturbance of the less than 100 viable metapopulations. The rationale for the subspecies’ T1 ranking cites its limited range, few remaining sites with extant populations, and significant threats to its habitat. Currently, there is no federal protection for the Nokomis fritillary or any of its subspecies in the United States under the Endangered Species Act, but the USDA Forest Service (USFS) has designated several subspecies as sensitive. The Great Basin silverspot butterfly has been designated as a sensitive species within USFS Region 2 (where it is found only in Colorado) and Region 3 (New Mexico and Arizona). Its Heritage Status Ranks are critically imperiled (S1) in Colorado and New Mexico, imperiled/vulnerable (S2/S3) in the Navajo Nation, and unranked (SNR) in Arizona and Utah. While the subspecies is afforded protected status in the Navajo Nation, it has no legal protection or special concern designations in any of the states where it occurs.

Primary Threats

The primary threat to Great Basin silverspot butterflies is habitat loss. Essential habitat components include wetlands associated with flowing water (i.e., springs, seeps, wet meadows), an abundance of their larval foodplant (e.g., bog violet [ nephrophylla]), and the availability of adult nectar sources (mostly composites) during the adult flight. These habitat conditions are scarce in the arid Southwest and tend to occur as small, widely separated and isolated fragments within the arid landscape. Modifications to hydrology (e.g., water diversion projects, capping springs, and draining wetlands), housing developments, and mineral extraction (e.g., gravel mining) have all contributed to further habitat loss and fragmentation. These activities represent the greatest historic, current, and future threats to the long-term survival of the Great Basin silverspot butterfly. Excessive livestock grazing is a threat to Great Basin silverspot butterflies by degrading their habitat and eliminating nectar sources, but light to moderate grazing may actually benefit the butterflies by giving a competitive advantage to their larval foodplants. Other threats to habitat quality and the availability of critical resources (e.g., nectar , larval foodplants) include indiscriminant use of herbicides, invasive species, and invasive adventive woody species. Fire, grazing, and haying can play important roles in maintaining and shaping these wetland communities, so the complete absence of these natural processes and land management practices may constitute a threat to their extent and quality. However, they can also pose direct and indirect threats to Great Basin silverspot butterflies, depending on their timing and intensity. Other direct threats to Great Basin silverspot butterflies can include extreme weather (e.g., harsh winters, late frosts, severe storms, unusually cool wet growing seasons), indiscriminant use of insecticides, disease, predation, and commercial collecting. A reduction in fitness resulting from genetic isolation may also pose a long-term threat.

Primary Conservation Elements, Management Implications and Considerations

Great Basin silverspot butterflies require streamside meadows and seepage areas, an abundance of their larval foodplant (bog violet), and the availability of adult nectar sources during their adult flight. In the arid Southwest, these habitat conditions are widely separated and isolated; therefore, butterfly colonies are small and isolated. Great Basin silverspot butterflies do not migrate, but they are strong fliers and able to move among colonies within a continuous riparian corridor. However, it is unlikely that they disperse long distances between highly isolated riparian systems. Conservation strategies should therefore focus on protecting as many colonies as possible within a riparian system, and maintaining the quality and continuity of the riparian habitat between them. Historic loss, fragmentation, and degradation of wetland communities and riparian corridors have contributed to the decline and current vulnerability of Great Basin silverspot butterfly populations. To prevent further losses, critical habitat areas (e.g., riparian wetland 2 3 communities with bog violet) must be identified, protected, and managed to maintain or improve their size, quality, and connectivity. Management should be directed toward eliminating invasive exotic woody species and controlling native woody species (e.g., preventing willows from forming dense, closed stands), eliminating exotic species, increasing the vigor of the larval foodplant, and maintaining adequate nectar sources. Small isolated Great Basin silverspot butterfly populations are now more vulnerable to events that they might have survived in the pre-settlement landscape, so management activities must avoid exacerbating those vulnerabilities. The timing, intensity, extent, and duration of management activities such as prescribed fire, grazing, and haying must ensure that critical resources (e.g., nectar plants, larval foodplants) are available when they are needed. Management activities must also mitigate any direct mortality that might result from such activities.

4 5 TABLE OF CONTENTS

ACKNOWLEDGMENTS ...... 2 AUTHOR’S BIOGRAPHY...... 2 COVER PHOTO CREDIT ...... 2 SUMMARY OF KEY COMPONENTS FOR CONSERVATION OF THE GREAT BASIN SILVERSPOT BUTTERFLY...... 3 Status...... 3 Primary Threats...... 3 Primary Conservation Elements, Management Implications and Considerations...... 3 LIST OF TABLES AND FIGURES ...... 7 INTRODUCTION ...... 8 Goal...... 8 Scope...... 9 Treatment of Uncertainty ...... 9 Application and Interpretation Limits...... 9 Publication of Assessment on the World Wide Web ...... 9 Peer Review ...... 9 MANAGEMENT STATUS AND NATURAL HISTORY ...... 10 Management Status ...... 10 Existing Regulatory Mechanisms, Management Plans, and Conservation Strategies...... 12 Biology and Ecology...... 13 Systematics and general species description...... 13 Systematics...... 13 General species description ...... 14 Distribution, abundance, and population trends...... 17 Global perspective...... 17 Regional distribution, abundance, and population trends ...... 17 Populations outside Region 2 ...... 20 Developmental phenology, activity pattern, and mobility ...... 20 Developmental phenology...... 20 Activity pattern...... 21 Mobility and migration...... 22 Habitat ...... 22 Food habits ...... 23 Nectar plants...... 23 Larval foodplants...... 23 Breeding biology...... 24 Courtship and mating ...... 24 Oviposition behavior ...... 24 Larval stages...... 24 Demography...... 25 Genetic characteristics and concerns...... 25 Hybridization...... 25 Ecological influences on survival, reproduction, and population growth ...... 26 Community ecology ...... 27 Disease, parasitism, and predation ...... 27 Competition ...... 27 Envirogram...... 27 CONSERVATION...... 29 Threats...... 29 Habitat loss/conversion ...... 29 Altered hydrology ...... 29 Grazing effects ...... 29 4 5 Exotic species...... 30 Pesticides...... 30 Prescribed burning and wildfires...... 30 Over-utilization for commercial, recreational, scientific, or educational purposes...... 31 Environmental factors ...... 31 Conservation Status of the Great Basin Silverspot Butterfly in Region 2 ...... 31 Potential Management of the Great Basin Silverspot Butterfly in Region 2 ...... 32 Implications and potential conservation elements ...... 32 Tools and practices ...... 32 Habitat management...... 32 Inventory and monitoring...... 34 Information Needs...... 34 Inventory and monitoring...... 34 Grazing impacts...... 35 Fire management impacts...... 35 DEFINITIONS...... 36 REFERENCES ...... 37

EDITORS: Gary Patton, Richard Vacirca, and John Sidle, USDA Forest Service, Rocky Mountain Region

6 7 LIST OF TABLES AND FIGURES

Tables: Table 1. Natural Heritage Program Global, National, and State Status Ranks...... 12 Table 2. Comparison of ventral hindwing disc color in Nokomis fritillary subspecies...... 16

Figures: Figure 1. National Forest System lands within USDA Forest Service Region 2...... 8 Figure 2. Natural Heritage Program state status ranks and county distribution records for the Nokomis fritillary species in the United States...... 10 Figure 3. County distribution records for Nokomis fritillary subspecies throughout their range in North America...... 11 Figure 4. Nokomis fritillary male dorsal (top), female dorsal (middle), and male ventral (bottom)...... 15 Figure 5. Great spangled fritillary egg (top left; similar to Nokomis fritillary); Nokomis fritillary pupae (top right), and larvae (bottom)...... 16 Figure 6. County distribution and Natural Heritage Program records for Great Basin silverspot butterflies, and National Forest System lands within Region 2...... 18 Figure 7. Great Basin silverspot butterfly life history stages and their approximate seasonal phenology. ... 21 Figure 8. Envirogram for the Great Basin silverspot butterfly...... 28

6 7 INTRODUCTION Goal

This conservation assessment is one of many Species conservation assessments produced for being produced for the Species Conservation Project the Species Conservation Project are designed to provide being undertaken by the USDA Forest Service land managers, biologists, and the public with a thorough (USFS), Rocky Mountain Region (Region 2) (Figure discussion of the biology, ecology, conservation status, 1). The Great Basin silverspot butterfly is the focus and management of certain species based on available of an assessment because USFS Region 2 lists it as a scientific knowledge. The assessment seeks to provide sensitive species. Within the USFS, a sensitive species critical summaries of scientific knowledge, discussions is a or whose population viability is of conservation implications of that knowledge, and an identified as a concern by a Regional Forester because outline of information needs. The assessment does not of significant current or predicted downward trends seek to prescribe management; rather, it provides the in abundance and/or in habitat capability that would ecological background upon which management must reduce its distribution [FSM 2670.5 (19)]. A sensitive be based and focuses on the consequences of changes species may require special management, so knowledge in the environment that result from management (e.g., of its biology and ecology is crucial. This assessment management implications). It discusses management addresses the biology of the Great Basin silverspot recommendations proposed or implemented elsewhere. butterfly throughout its range, but emphasizes Region 2 as information permits.

Figure 1. National Forest System lands within USDA Forest Service Region 2. 8 9 Scope develop strong inference (Platt 1964). However, it is difficult to conduct critical experiments that produce The Great Basin silverspot butterfly conservation clean results in the ecological sciences. Often, we assessment examines the biology, ecology, conservation must rely on observations, inference, good thinking, status, and management of this taxon with specific and models to develop and test predictions, and to reference to the geographic and ecological characteristics guide our understanding of ecological relationships. of the southern Rocky Mountain region. Although some Confronting uncertainty, then, is not prescriptive. In of the literature on this species originates from field this assessment, the strength of evidence for particular investigations outside the region, this document places ideas is noted, and alternative explanations are that literature in the ecological and social contexts of the described where appropriate. southern Rocky Mountain region. Application and Interpretation Limits In producing the assessment, I reviewed refereed literature, non-refereed publications, research reports, Information used to complete this assessment and data accumulated by agencies and butterfly focused on studies from across the geographical experts. Not all publications on Great Basin silverspot range of the Great Basin silverspot butterfly, and to a butterflies are referenced in the assessment, nor were lesser extent, the range of the other Nokomis fritillary all published materials considered equally reliable. subspecies. Most information should apply broadly The assessment emphasizes refereed literature because throughout the subspecies’ range, but certain life this is the accepted standard in science. Non-refereed history parameters may vary along environmental publications or reports were used when information gradients. Inferences made from this information was unavailable elsewhere, but they were regarded regarding threats to the subspecies are understood to with greater skepticism. Unpublished data (e.g., Natural be limited in scope (see section above) and take into Heritage Program records, research reports, reports account the particular conditions present in Region from butterfly experts) were important in estimating the 2. Therefore, information regarding the conservation geographic distribution of this species. Natural Heritage status of this subspecies pertains specifically to Region Program element occurrence records for the Great 2 and does not necessarily apply to other portions of the Basin silverspot butterfly were obtained for Colorado subspecies’ range. (the only state in Region 2 where it occurs), and were supplemented with data from other sources (e.g., Publication of Assessment on the World published distribution maps, research reports, state Wide Web experts) for a more complete picture of its distribution and status. These data required special attention To facilitate use of these conservation because of the diversity of persons and methods assessments, they are being published on the Region used in collection. Often the butterfly data were only 2 World Wide Web site (www.fs.fed.us/r2/projects/scp/ available as county records. More specific data (e.g., assessments). Placing the documents on the Web makes dates, locations, population trends) would have been them available to agency biologists and the public more helpful, and while attempts made to obtain additional rapidly than publishing them as reports. In addition, documentation met with some success, tracking down it facilitates their update and revision, which will be and evaluating the accuracy of individual records were accomplished according to protocols established by beyond the scope of this assessment. Region 2.

Treatment of Uncertainty Peer Review

Science represents a rigorous, systematic In keeping with the standards of scientific approach to obtaining knowledge. Competing ideas publication, assessments developed for the Species regarding how the world works are measured against Conservation Project have been externally peer reviewed observations. However, because our descriptions of the prior to their release on the Web. This assessment was world are always incomplete and our observations are reviewed through a process administered by the Society limited, science focuses on approaches for dealing with for Conservation Biology, which chose two recognized uncertainty. A commonly accepted approach to science experts (on this or related taxa) to provide critical input is based on a progression of critical experiments to on the manuscript.

8 9 MANAGEMENT STATUS AND G3. The rational for the G3 ranking cites the species’ NATURAL HISTORY very spotty distribution in wet places that are associated with generally arid range, disturbance and significant Management Status problems at many sites, and increasing isolation of the less than 100 viable metapopulations (NatureServe The historic range of the Nokomis fritillary species 2006). The National Heritage Status Rank for United extended from eastern California through Nevada and States populations is N3. The Global Heritage Status Utah to western Colorado, and south through eastern Rank for the Great Basin silverspot butterfly subspecies Arizona and New Mexico to northern Mexico (Figure is critically imperiled (G3T1), based on its “limited 2, Figure 3). NatureServe (2006) has determined that range, few remaining sites, and significant threats to the Nokomis fritillary species is globally vulnerable habitats” (NatureServe 2006). These ranks were last and has assigned it a Global Heritage Status Rank of reviewed and changed on 30 September 1998. The

Figure 2. Natural Heritage Program state status ranks and county distribution records for the Nokomis fritillary species in the United States (adapted from NatureServe 2006). 10 11 Figure 3. County distribution records for Nokomis fritillary subspecies throughout their range in North America.

10 11 World Conservation Union does not provide a global ranks and county distribution records for the Nokomis classification ranking for the Nokomis fritillary species fritillary are illustrated in Figure 2. Global, national, or any of its subspecies (IUCN 2004). and state status ranks for the Nokomis fritillary and each of its subspecies that have been recorded in the United Both the Great Basin silverspot butterfly and blue States are summarized in Table 1. silverspot butterfly Speyeria ( nokomis caerulescens) subspecies were designated as candidates for listing Existing Regulatory Mechanisms, under the Endangered Species Act (ESA) until 1996 Management Plans, and Conservation (U.S. Fish and Wildlife Service 1984, 1989, 1991, 1994, Strategies 1996), but they were never listed. USFS Regions 2 and 3 have designated the Great Basin silverspot butterfly The Nokomis fritillary and its subspecies do not as a sensitive species (USDA Forest Service 2004). have legal protection at either federal or state levels. In Region 2, this subspecies is found only in western The Navajo Nation, however, has given the Great Basin and south-central Colorado. The sensitive species silverspot butterfly a Group 3 designation (i.e., prospects listing rationale in Region 2 cites the small size and of survival or recruitment are likely in jeopardy in the isolation of populations, compromised metapopulation foreseeable future), which gives it legal protection dynamics, and widespread loss and modification of as an endangered species (Navajo Fish and Wildlife the very limited springs and spring-fed wetlands that Department 2005). Listing of the Great Basin silverspot the butterflies require (USDA Forest Service 2003). butterfly as a sensitive species in USFS Regions 2 and Specific threats listed in the sensitive species evaluation 3 does not confer legal protection, but it does help include loss and degradation of their habitat resulting to ensure that appropriate conservation/management from draining, capping springs, and development objectives and practices are implemented on National (USDA Forest Service 2001). Forest System lands.

There are historic records for the Great Basin No formal recovery plans have been developed silverspot butterfly subspecies from four states and for the Nokomis fritillary or its subspecies, but the Navajo Nation. State Heritage Status Ranks are recovery plans developed for similar fritillary critically imperiled (S1) in Colorado and New Mexico, species (e.g., Oregon silverspot butterfly [Speyeria imperiled/vulnerable (S2/S3) in the Navajo Nation, zerene hippolyta]; U.S. Fish and Wildlife Service and unranked (SNR) in Arizona and Utah. State status 2001) may provide helpful conservation guidelines.

Table 1. Natural Heritage Program Global, National, and State Status Ranks1 for the Nokomis fritillary and its subspecies (Adapted from NatureServe 2006). Speyeria S. n. S. n. S. n. nokomis S. n. nokomis S. n. nitrocris coerylescens apacheana carsonensis Global G3 G3T1 G3T3 G3T1T3 G3T2 G3T1 USA (National) N3 N1 N3 NX N2 N1 USA (State) Arizona SNR SNR SNR SH — — California S3 — — — SNR S1 2 Colorado S1 S1 SNR — — — Navajo Nation SNR S2S3 — — — — Nevada SNR — — — S2 S1 New Mexico SNR S1 SNR — — — Utah S2? SNR — — — — 1 Status Rank Definitions: G1/T1/N1/S1 = Critically Imperiled G-ranks = Global Status Ranks G2/T2/N2/S2 = Imperiled N-ranks = National Status Ranks G3/T3/N3/S3 = Vulnerable S-ranks = State Status Ranks SNR = Not ranked T-ranks = Global Status Ranks for Subspecies 2 USFS Region 2 State

12 13 Furthermore, The Nature Conservancy of Colorado Speyeria nokomis wenona dos Passos & Grey and the U.S. Bureau of Land Management (BLM) in 1945; Wenona fritillary Grand Junction, Colorado have developed a habitat Controversial or Unresolved : None at management plan for the Great Basin silverspot the species level; see discussion of subspecies butterfly population at the Unaweep Canyon, Mesa designation (below) County, Colorado (Ellis 1989). Nokomis fritillary is the generally accepted General conservation and management resources common name for Speyeria nokomis (Miller 1992, developed for prairie include principles that North American Butterfly Association 2001), and it is may be relevant to Great Basin silverspot butterfly typically used for the subspecies S. n. nokomis (Tilden conservation. Opler (1981) and Panzer (1988) present and Smith 1986, NatureServe 2006). This subspecies general guidelines for managing prairies for is also commonly called the Great Basin silverspot conservation, and Moffat and McPhillips (1993) provide butterfly (Colorado Natural Heritage Program 2005b), a literature review and general guidebook for managing and the USFS Region 2 uses this name in its rationale butterflies in the northern Great Plains. Various research for designating the subspecies as a sensitive species papers (Dana 1989, Dana 1991, Swengel 1996, Panzer (USDA Forest Service 2003). For this manuscript, 1998, Swengel 1998, Swengel and Swengel 1999, Nokomis fritillary will be used when referring to the Swengel and Swengel 2001, Panzer 2002) and a species, and Great Basin silverspot butterfly will be fairly comprehensive review of literature dealing with used when referring to the subspecies. prairie insect management issues (Swengel 2001) also provide management guidelines that may be relevant. NatureServe (2006) states that subspecies of A synthesis of general principles and guidelines from the Nokomis fritillary are “unusually clearcut for these resources, and specific Great Basin silverspot a Speyeria,” but differences in opinion over the butterfly conservation issues, are presented in more definitions of those subspecies still exist and make it detail in the Conservation section of this paper. difficult to assign populations to a particular taxon. A brief overview of the taxonomic history of the species is Biology and Ecology presented to provide a better context for evaluating the distribution and conservation status of the subspecies Systematics and general species description (adapted from NatureServe 2006). dos Passos and Grey (1947) recognized six subspecies (S. nokomis Systematics apacheana, S. n. coerulescens, S. n. nigrocaerulea, S. n. nitocris, S. n. nokomis, and S. n. wenona). dos Passos Classification and Nomenclature (1964) reduced the number of subspecies by placing Scientific name:Speyeria nokomis nokomis S. n. nigrocaerulea and S. n. nitocris under synonymy Common name: Great Basin silverspot butterfly; with S. n. nokomis, but he did not give reasons for the Nokomis fritillary changes. Ferris and Fisher (1971) later challenged that Class: Insecta (Insects) arrangement and proposed that S. n. nokomis and S. n. Order: (Butterflies and Moths) nitocris be retained as a formal subspecies, and that Superfamily: Papilionoidea (True Butterflies) S. n. nigrocaerulea should be considered a far eastern Family: (Brush-footed Butterflies) form and synonym of S. n. nitocris. They based those Subfamily: (Heliconians and Fritillaries) recommended revisions on differences in “facies, : Speyeria Scudder, 1872 habitat, and geographic location.” Miller and Brown Specific name:nokomis (Edwards, 1862) (1981) proposed a similar revision, but they placed S. Common name: Nokomis fritillary n. nigrocaerulea under synonymy with S. n. nokomis Other subspecies: rather than S. n. nitocris. More recently, Austin (1998) Speyeria nokomis apacheana (Edwards, 1862); proposed recognizing a distinct phenotype of S. n. Apache fritillary apacheana in western Nevada as a separate subspecies Speyeria nokomis carsonensis Austin, 1998; (S. n. carsonensis). Carson Valley silverspot butterfly Speyeria nokomis coerulescens (Holland, 1900); Depending on the taxonomic view adopted, a bluish fritillary subspecies can be considered narrowly endemic or Speyeria nokomis nitocris (Edwards, 1874); widely distributed, and this has important implications nitocris fritillary for its conservation (e.g., justification for listing under

12 13 the ESA). Under the classification of dos Passos (1964), blackish, depending on the subspecies. It is adorned by Speyeria nokomis nokomis includes S. n. nigrocaerulea large black-bordered silver spots that are the basis for and S. n. nitocris and would be broadly distributed in the “silverspot” common name. The ventral hindwing Colorado, Utah, Arizona, New Mexico, and perhaps is also characterized by a fairly wide submarginal band even Nevada. Based on the most restrictive definition of that is tan in males and yellow-green in females. S. n. nokomis, in which S. n. nigrocaerulea is considered a synonym of S. n. nitocris (Ferris and Fisher 1971), the The color of the ventral hindwing disc is useful subspecies is narrowly endemic and restricted to a few for differentiating the subspecies, and the typical color locations in western Colorado and eastern Utah. If S. n. per subspecies is summarized in Table 2. Great Basin nigrocaerulea is considered a synonym of S. n. nokomis silverspot butterflies are characterized by a light brown (Miller and Brown 1981), then the range also includes disk color in males and a deep olive color in females. portions of northern Arizona and New Mexico. Clinal Apache fritillaries are found to the west, with a hybrid variation also complicates the issue. Relatively pure blend zone with Great Basin silverspot butterflies in forms of S. n. apacheana are found in California and Utah. Their disk color is more yellowish buff in males Nevada, and relatively pure forms of S. n. nokomis and light olive-green in females. Nitochris fritillaries are found in western Colorado, but there appears to occur immediately to the south of the Great Basin be a blend zone in Utah. Eastern Utah populations silverspot butterfly’s range in central to southern are predominantly S. n. nokomis, and western Utah Arizona and New Mexico. Their disk color is deep populations are predominantly S. n. apacheana (Swisher reddish brown in males and black in females. and Morrison 1969, Ferris and Fisher 1971). The western subspecies of the great spangled For this manuscript, butterfly nomenclature fritillary (Leto fritillary [Speyeria cybele leto]) is the only follows Opler and Warren (2003) for scientific butterfly with an overlapping range (Utah to California) names, and the North American Butterfly Association that can be confused with the Nokomis fritillary. It has (2001) for English names. However, those references an earlier flight (July to August), is generally smaller, generally only include species, so for subspecies and the ventral surface of the hindwing is dark-brown, designations of the Nokomis fritillary, we follow has fewer and smaller silver spots, and has a narrower the more recent and generally accepted taxonomic submarginal band (Ferris and Brown 1981, Scott 1986, treatments of Miller and Brown (1981), as modified by Opler and Wright 1999). However, its range and habitat Austin (1998). Thus, in this assessment, we recognize do not overlap with those of the Great Basin silverspot Speyeria nokomis apacheana, S. n. carsonensis, S. n. butterfly, so confusion with Leto fritillary should not coerulescens, S. n. nitocris, S. n. nokomis, and S. n. be a problem for this subspecies. [Adult descriptions wenona. Plant nomenclature follows the National Plant were adapted from Ferris and Brown 1981, Scott Data Center (USDA Natural Resources Conservation 1986, Tilden and Smith 1986, Opler and Wright 1999, Service 2005). NatureServe 2006.]

General species description Nokomis fritillary eggs are cream-colored at the time they are laid, become speckled with brown soon Adult Nokomis fritillaries are among the largest after that, and then become tan after a few days (Scott species in the genus Speyeria, with a wingspan from and Mattoon 1981, Scott 1986). Scott (1986) describes 6.3 to 7.9 cm (2.5 to 3.1 inches). Males have a dorsal the general appearance of the eggs as “dirty-white with wing surface that is predominantly orange-brown purplish markings.” They also have strong vertical ribs with black markings, and lightly to greatly darkened connected by numerous horizontal crossbars that rise wing bases (Figure 4, upper). Near the wing margins, to peaks surrounding the micropyle (Figure 5, upper black markings include a distinct marginal line and a left; great spangled fritillary egg illustrated; Scott and row of submarginal chevrons. Females have a dorsal Mattoon 1981). There are six larval instars, and the wing surface with more extensive darkening of the head capsule widths range from approximately 0.35 wing bases, and the outer portion is predominantly mm for the first instar to 3.5 mm for the sixth instar white-cream or bluish-white, rather than orange-brown (Scott and Mattoon 1981). Scott (1986) describes (Figure 4, middle). The ventral wing surfaces are Nokomis fritillary larvae as “. . . orangish-ochre, dark similar in both sexes (Figure 4, lower). Forewings are beneath, with six rows of long orangish-ochre spines, mostly orange-brown. The hindwing disc (area between black patches around dorsal and subdorsal spines, two the veins at the wing base) has a ground color ranging black transverse stripes on the rear of each segment, from light-to-dark cinnamon brown, deep olive, or and orangish-ochre lateral and dorsal stripes; head 14 15 Figure 4. Nokomis fritillary male dorsal (top), female dorsal (middle), and male ventral (bottom). Photographs © Nearctica.com, Inc. 2000 (used with permission). 14 15 Table 2. Comparison of ventral hindwing disc color in Speyeria nokomis subspecies (Adapted from Tilden and Smith 1986, Austin 1998). Subspecies Male Female S. n. apacheanna yellowish buff light olive-green S. n. carsonensis buff; slightly greenish aspect buff; olive-yellow aspect S. n. coerulescens red-brown brown to green S. n. nitocris deep reddish brown black S. n. nokomis light brown deep olive

Figure 5. Great spangled fritillary egg (top left; similar to Nokomis fritillary); Nokomis fritillary pupae (top right), and larvae (bottom). Illustration and photographs from James A. Scott, The Butterflies of North America, © 1986 by the Board of Trustees of the Leland Stanford Jr. University. Used with permission of Stanford University Press, www.sup.org. 16 17 black, orangish on top rear” (Figure 5, lower). There the subspecies from eastern California through Nevada. are subtle color differences between some of the Utah is a hybrid blend zone, with Apache fritillary subspecies in later instars (e.g., third to sixth instars). forms dominating in the west and Great Basin silverspot Speyeria nokomis nokomis and S. n. apachaena have an butterfly forms dominating in the east (Swisher and orangish-ochre ground color, and S. n. coeruleucens has Morrison 1969, Ferris and Fisher 1971). The Great a light yellow ground color (Scott and Mattoon 1981). Basin silverspot butterfly subspecies has a fairly limited The pupae (chrysalises) are described by Scott (1986) distribution from Uintah and San Juan counties in eastern as “. . . orangish-ochre, with a black transverse serrate Utah to western Colorado, and south to northeastern band on the front of each abdomen segment, the thorax Arizona and northern New Mexico (Figure 3, Figure and all but the center of the wing black, and the top of 6). Farther south, the nitochris fritillary subspecies is the thorax with an orangish triangular spot” (Figure found in eastern Arizona and western New Mexico. 5, upper right). The subspecies exhibit differences in There are unconfirmed historic records for the Bluish the extent of black, especially on the wing cases. S. fritillary subspecies from Pima and Cochise counties n. nokomis are fairly dark with wing cases that are in southeastern Arizona, and Otero County in southern mostly black, S. n. apachaena are lighter with lighter New Mexico, but its current range is probably restricted wing cases, and S. n. coeruleucens are still lighter with to the states of Chihuahua and Durango in Mexico. wing cases that are predominantly light but occasionally The Wenona fritillary has only been documented from darker and abdomens that are somewhat lighter (Scott Nuevo Leon, Mexico. It was not found during repeated and Mattoon 1981). expeditions to those habitats (1972 and 1981 McCorkle observations; cited in Hammond and McCorkle 1983) Distribution, abundance, and population trends and may now be extinct.

Global perspective The Nokomis fritillary species is fairly widespread, but throughout its range, it depends on The historic range of the Nokomis fritillary small isolated, wetland habitats in an arid landscape. species includes basin and range country from the Sierra These habitats are threatened by hydrologic changes, Nevada in eastern California through Nevada and Utah development, abusive land use practices (e.g., excessive to the Rocky Mountains in western Colorado, and south grazing; gravel and mineral mining), and increasing through eastern Arizona and New Mexico to northern isolation of the less than 100 viable metapopulations. Mexico (Figure 2, Figure 3). It has been recorded from Therefore, the Global Heritage Status Rank for the at least 56 counties in six states in the U.S., and three species is vulnerable (G3) (NatureServe 2006). The states in Mexico. Determining the historic range for the Great Basin silverspot butterfly subspecies has a much individual subspecies is problematic due to differences more limited range. It has been recorded from at least in opinion over their classification, clinal variation 20 counties in four states (Arizona = 1 county [includes within portions of the range, and the tendency for Navajo Nation]; Colorado = 11 counties; New Mexico publications to present distribution data at the species = 4 counties; Utah = 4 counties). The Global Heritage level rather than the subspecies level. Figure 3 provides Status Rank for the subspecies is critically imperiled a rough estimate for the historic county distribution (G3T1), based on its “limited range, few remaining and range for each subspecies based on the subspecies sites, and significant threats to habitats” (NatureServe definitions adopted for this paper (Miller and Brown 2006). The distribution and trends for the Great Basin 1981), and an interpretation of the data available within silverspot butterfly are covered in more detail below. that framework. The Carson Valley silverspot butterfly is a distinct phenotype of the Apache fritillary that was Regional distribution, abundance, and recently recognized as a separate subspecies (Austin population trends 1998). It has a very limited distribution at the western extent of the Nokomis fritillary’s range in eastern Colorado (S1): The Great Basin silverspot California and western Nevada. Austin (1998) describes butterfly is the only Nokomis fritillary subspecies found its range as “. . . isolated colonies in wet meadows along in Region 2, and Colorado is the only state in the region the eastern base of the Carson Range from southern where it occurs. There, it has been documented from Washoe County, Nevada south to northern Alpine 11 counties in the western and south-central portions of County, California, in the Pine Nut Mountains, Douglas the state (Ferris and Brown 1981, Stanford and Opler County, Nevada and into the Sweetwater Mountains, 1993, Opler et al. 2006). The Colorado Natural Heritage Lyon County, Nevada.” The Apache fritillary has a Program (2005a) has eight element occurrence records much broader distribution, with relatively pure forms of in their database from six of those counties (Figure 6). 16 17 ies and National Forest System lands within Region 2. County distribution and Natural Heritage Program records for Great Basin silverspot butterfl Figure 6. Figure

19 Ehrlich (1983) found an additional population along the Natural Heritage Program (2005a) has given it an Green River in Dinosaur National Monument, Moffat element occurrence rank of A (excellent estimated County that is not included in the Colorado Natural viability). This population includes five confirmed small Heritage Program database. However, many of these (5 to 20 acres) colonies along a 5-mile stretch of West historic populations have not been seen in more than Creek, and additional habitat about 2.5 miles further 15 years, and their current status is unknown. The upstream that could support a colony (Ellis 1989). Colorado Natural Heritage Program (2004) states that About two-thirds of the largest colony is on BLM- recently verified colonies occur at only four previously administered land that was designated as a Research known locations in La Plata, Mesa, Montrose, and Natural Area in 1983 (U.S. Department of the Interior, Ouray counties. During surveys in 1997, B. Williams of Bureau of Land Management 1985). The presumed the University of Wisconsin (personal communication neotype location for the Great Basin silverspot butterfly 2006) found extant populations at only two sites: one in is at Mount Sneffels, near the town of Ouray in Ouray Unaweep Canyon in Mesa County and one southwest County (dos Passos and Grey 1947, Grey 1989). The of the original Moffat County site (Ehrlich 1983), Colorado Natural Heritage Program (2005a) includes located closer to the Utah border in Dinosaur National BLM, USFS, and private lands in the description for Monument. At least one population in La Plata County the element occurrence record, which falls within the has been eliminated as a result of housing developments southeastern unit of the Uncompahgre National Forest (Opler personal communication 2000, cited in (Figure 6). Ellis (1989) examined this site in September NatureServe 2006; Williams personal communication 1989 and found that it was abusively overgrazed and 2006), and the putative neotype site in Ouray County that most of the willow thickets had been stripped by was being “abusively overgrazed” when Ellis (1989) year-round horse grazing. No additional information examined it in September 1989. Mineral extraction was found for the current status of this population. is also a threat at many sites. Surveys are needed to confirm the status of historic populations in the state The San Juan National Forest includes parts and to attempt to locate new populations. of Archuleta, La Plata, Montezuma, and San Juan counties, and there are county records for the Great Among National Forest System lands in Region Basin silverspot butterfly in each of those counties 2, the Great Basin silverspot is known to occur on or (Stanford and Opler 1993, Opler et al. 2006). There near the Grand Mesa/Uncompahgre/Gunnison, San are two element occurrence records from La Plata Juan, and Rio Grande national forests in Colorado. In County in or near the south-central portion of the forest 1999, Ray Stanford suggested that the butterfly could (Figure 6), but the last observations at those sites were occur in seepy areas uphill from the town of Rifle in in 1980 and 1981 (Colorado Natural Heritage Program Garfield County, near the western edges of the White 2005a). Ellis (1989) visited one of those sites (Animas River National Forest (Potter personal communication River site) in 1986 and found that it was severely 2005). However, Kim Potter of the USFS (personal disturbed by gravel mining. Housing developments are communication 2005) states that the Great Basin a major threat in the area, and at least one of those La silverspot has not been found in that area or on the Plata County populations has been eliminated (Opler forest, and the closest known population is at Unaweep personal communication 2000, cited in NatureServe Canyon, Mesa County. If this butterfly occurs on the 2006; Williams personal communication 2006). There forest, it is most likely to occur in far western units to are also two historic (more than 15 years since the the north and south of the town of Rifle (e.g., Garfield, last observation) element occurrence records from Mesa, western Pitkin, and Rio Blanco counties). Archuleta County, just south of the eastern portion of the San Juan National Forest (Figure 6); there are no The Grand Mesa/Uncompahgre/Gunnison data on their current status (Colorado Natural Heritage national forests contain habitat and known records Program 2005a). of the Great Basin silverspot butterfly (Abramson personal communication 2005). The northwest portion The southern portion of the Rio Grande National of the Uncompahgre National Forest (the Uncompahgre Forest includes western Conejos County, where there Plateau) is immediately south of the large Unaweep is one element occurrence record just east of the forest Canyon population in Mesa County (Figure 6). The boundary (Figure 6). This population has an element Unaweep Canyon population is the largest known occurrence rank of C (fair estimated viability) and Great Basin silverspot butterfly population in Colorado, was last observed in 1999 (Colorado Natural Heritage and it is probably second in size to the largest known Program 2005a). The USFS Region 2 sensitive species population in Uintah County, Utah. The Colorado evaluation states that the Great Basin silverspot 19 butterfly is likely to occur in the San Juan andRio 1992, NatureServe 2006), and Mora, San Miguel, and Grande national forests (USDA Forest Service 2001), Taos counties in the north-central portion of the state but there are no recent data on the status of historic (Cary and Holland 1992). Cary and Holland (1992) list populations in or near those National Forest System the Great Basin silverspot butterfly as a resident of each lands. Surveys are needed to confirm the status of those of those counties, but they do not provide additional historic populations and to search for new populations. information on the status of those populations. The San Juan County records likely correspond to Navajo All other National Forest System lands in Nation populations (see above). Colorado (e.g., Arapaho/Roosevelt National Forest and Pawnee National Grassland, Medicine Bow/Routt Utah (SNR): There are historic Great Basin National Forest and Thunder Basin National Grassland, silverspot butterfly records from Duchesne and Uintah and Pike/San Isabel National Forest and Comanche/ counties in northeastern Utah, Grand County in east- Cimarron National Grassland) are east of the Great central Utah, and San Juan County in southeastern Basin silverspot butterfly’s documented range. It has Utah (Ferris and Fisher 1971, NatureServe 2006, Opler not been documented in or near those National Forest et al. 2006). Ferris and Fisher (1971) suggest that the System lands (Cox personal communication 2005, distribution of the Great Basin silverspot butterfly Lowry personal communication 2005), and it is unlikely in Utah might be restricted to San Juan and Uintah that it will be. counties, and that populations farther west represent a hybrid blend zone with the Apache fritillary. The Populations outside Region 2 type location for the Great Basin silverspot butterfly is generally thought to be Mount Sneffels, Ouray County, Arizona (SNR): The only records for the Great Colorado (Grey 1989), but other authors (Brown Basin silverspot butterfly in Arizona are from Apache 1965, Ferris and Fisher 1971) have suggested that the County (NatureServe 2006). No additional data type material might have actually been collected in were available for those records, but it is likely that the vicinity of Hatch Wash, San Juan County, Utah. they reference the same populations included in the Ferris and Fisher (1971) describe the Uintah County discussion for the Navajo Nation (see below). site as a “rather unrewarding looking meadow” with willow, violets, and constant water flow. Despite this Navajo Nation (S2/S3): The Navajo Nation rather bleak description, this site, located along Ashley includes parts of Arizona, New Mexico, and Utah. Creek north of Vernal, is the largest known Great Basin Occurrences for the Great Basin silverspot butterfly on silverspot butterfly colony (Ellis 1989). Ehrlich (1983) Navajo Nation lands correspond to portions of Apache suggested that “rampant” mineral development might County, Arizona and San Juan County, New Mexico in threaten the privately owned Uintah County populations. the Chuska Mountains and Defiance Plateau. In 1994, Williams (personal communication 2006) found extant there were two known populations, but since then, an populations of the Great Basin silverspot butterfly in the additional 10 or 11 breeding populations have been Uintah County portion of Dinosaur National Monument found. Each colony is typically 1 to 2 acres in size, during 1997 surveys. Emmel et al. (1970) recorded and two or three observations per day are typical at a observations of an ovipositing female in 1969 north of site during peak flight. Most of the populations appear Mountain Home in Duchesne County. Updated data are to be stable. Threats include grazing as it is typically needed for these populations to determine their current practiced in the area (e.g., intense grazing by cows, status and long-term trends. horses, and sheep) and hydrologic changes resulting from water usage and drought. The Navajo Nation has Developmental phenology, activity pattern, and assigned the Great Basin silverspot butterfly a Group mobility 3 designation (i.e., prospects of survival or recruitment are likely in jeopardy in the foreseeable future), which Developmental phenology gives it legal protection as an endangered species (Navajo Fish and Wildlife Department 2005). [Status A generalized timeline summarizing the seasonal and distribution information adapted from Mikesic phenology for the principal stages of the Great Basin personal communication (2006)]. silverspot butterfly life cycle is presented in Figure 7. The primary source for immature stage length data is New Mexico (S1): There are historic Great Basin Scott and Mattoon (1981). They reared the butterflies silverspot butterfly records from San Juan County in under controlled laboratory conditions (about 20 °C) the northwestern corner of the state (Cary and Holland and found that the developmental time from oviposition 20 21 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Adult Flight (males)

Adult Flight (females)

Eggs (~17-18)

st 1 instar larvae (winter diapause)

st th 1 -6 instar larvae (~72-86 days; post-diapause)

Pupae (~17 days)

Adult emergence

Figure 7. Great Basin silverspot butterfly life history stages and their approximate seasonal phenology (adapted from Scott and Mattoon 1981).

to adult emergence was 61 days for males and 69 days 1981). Oviposition is delayed in many Speyeria species, for females. Natural conditions are cooler, on average, but no specific references to this were found for the than their laboratory setup, so they presumed that the Great Basin silverspot butterfly. development time would be longer in nature. By taking into account the approximate inactive period (winter Activity pattern diapause) and dates for adult emergence, they estimated a 4-month (about 108 days for males and 122 days for Nokomis fritillary males spend most of the day females) development period for natural populations. searching for females in the meadows or seeps that support their colonies (Scott 1986). Ferris (1969) The incubation period for the eggs was 10 days in observed nitochris fritillary mating behavior during the laboratory, which would translate to an estimated 17 three summers (1966-1968) in Arizona (Gila and to 18 days under natural conditions. First instar larvae Apache counties) and New Mexico (Catron County). enter winter diapause immediately after hatching, Males became active early in the morning as the dew and then resume development in the spring with the was drying (about 8:30 a.m. MST), and after feeding emergence of young violet leaves. Scott and Mattoon briefly, they spent the rest of the morning patrolling (1981) described six instars and the pupae, but they close to the ground without feeding. Females emerged did not provide data for the development time required either from the tree cover on adjacent slopes or from for each of those stages. Date ranges for immature life low shrubbery (mainly willows) adjacent to the streams stages in the timeline (Figure 7) are estimates derived about 1.5 to 2.0 hours later. They landed in the grass from the data that were available and the flight period, where they were discovered by the males. Paired and they should be used only as a very general guideline. courtship flights resulted, with attempted interference Great Basin silverspot butterflies are univoltine (having by other males. All courtship and mating behavior was a single generation per year) with an adult flight from observed between 11:00 a.m. and 1:00 p.m. Similar late July through the middle of September (Scott 1986, detailed behavioral observations for populations of Tilden and Smith 1986). The actual development times the Great Basin silverspot butterfly were not found. It for immature stages and the flight period for the adults is assumed that their behavior would be similar. Males vary somewhat across their range, and they can vary and females are thought to move more extensively significantly from year-to-year depending on weather along the riparian corridor when searching for nectar patterns. Females have a longer larval development (Ellis 1989). period and emerge about one to two weeks after the males. Delaying female emergence until males are Larvae of members of the genus Speyeria are more abundant may help “minimize the time required generally thought to be nocturnal, feeding at night for females to find a mate” and “maximize the number and resting during the day in a hidden location that of matings for males” (Scott 1977, Scott and Mattoon is usually away from the hostplant (Klots 1951, 20 21 Hammond 1974, Ferris and Brown 1981). However, as possible within a given riparian system, and on in field and laboratory studies of a Kansas population maintaining the quality and continuity of the riparian of regal fritillaries (S. idalia), all documented activity habitat between colonies. Adults might be capable of suggested that they are actually diurnal (daytime) dispersing greater distances (e.g., between riparian foragers (Kopper et al. 2001a). Foraging behavior corridors), but this is difficult to document, and no data need to be collected for the Great Basin silverspot evidence was found to confirm long-distance dispersal butterfly to determine whether it exhibits the typical for this species. nocturnal feeding behavior. Habitat Mobility and migration The Nokomis fritillary is associated with the Great Basin silverspot butterfly movements Upper Sonoran (pinyon-juniper, various shrubs) and fall into two categories defined by two different Canadian (fir-spruce-tamarack, some pine, aspen-maple- ecological boundaries (Ellis 1989). Males search for birch-alder-hemlock) Life Zones of the southwestern females within the meadows or seeps that define the United States and northern Mexico (Hammond 1974, colonies (the colony boundary), and it is assumed, Scott 1986). Habitats are generally described as but not proven, that individuals of both sexes travel permanent spring-fed meadows, seeps, marshes, and more extensively along riparian corridors (the habitat boggy streamside meadows associated with flowing continuity boundary) in search of nectar (Ellis 1989). water in arid country (Hammond 1974, Scott 1986, The localized patrolling of the males maximizes the Tilden and Smith 1986, Opler and Wright 1999, Brock probability of finding females, and the more extensive and Kaufman 2003). Hovanitz (1970) states that the movement along riparian corridors in search of nectar Nokomis fritillary “. . . is found throughout the basin increases the probability for exchange of individuals and range country from the eastern side of the Sierra among colonies (Ellis 1989). Nevada to the Rocky Mountains in widely separated isolated spots where there are cold water seepages, Great Basin silverspot butterflies do not migrate, and acid bogs, in the midst of otherwise alkaline but they are strong fliers and can move between country.” The presence of an adequate supply of the isolated colonies within a continuous riparian zone larval foodplant (i.e., bog violet []) (Arnold 1989, Fleishman et al. 2002). However, it is is a critical habitat component (NatureServe 2006). unlikely that they will disperse long distances between Microhabitat conditions for the bog violet include soggy highly isolated riparian systems. Therefore, for those soil and shade, often under shrubs such as willows populations to persist, the entire life cycle must be (Baird 1942). Willows are usually present (Hammond completed successfully each year at each colony or 1974) and probably help to create the microclimate that system of colonies within a given riparian system. At the violets need. An adequate supply of nectar sources Unaweep Canyon in Mesa County, Colorado, there is another important habitat requirement. Nokomis are five confirmed small (5 to 20 acres) colonies fritillaries utilize a variety of species, including native along a 5-mile stretch of West Creek (Ellis 1989). In and introduced thistles (e.g., Cirsium, Carduus, and a mark-recapture study by Arnold (1989), 50 percent Onopordon species), horsemint (Agastache), and joe of the recaptured butterflies had moved between two pye weed (Eupatorium maculatum) (NatureServe colonies separated by about 0.75 miles. Based on 2006). These microhabitats are naturally scarce in the those data, the butterfly’s strong flying ability, and the arid landscapes where they occur, and are threatened continuity of the riparian zone between colonies, Ellis by excessive livestock grazing and activities that alter (1989) speculated that there should be a routine (e.g., wetland hydrology (Hammond and McCorkle 1983). every 1 to 5 years) exchange of individuals among the colonies at that site. Fleischman et al. (2002) obtained Specific habitat requirements for the different similar results for the Apache fritillary subspecies in Nokomis fritillary subspecies are similar, but the Nevada. They documented routine dispersal distances context within which they occur can vary. In the United up to 4 km (2.5 miles), and 26 percent of the recaptured States, the Apache fritillary, Carson Valley silverspot butterflies had emigrated from the initial capture patch. butterfly, and Great Basin silverspot butterfly are This exchange of individuals mitigates short-term found in wet meadow and seep communities associated extinctions of individual colonies and helps to ensure with arid desert landscapes of the Upper Sonoran Life the long-term survival of the overall population (Ellis Zone, while the nitochris fritillary is found in similar 1989, Fleischman et al. 2002). Therefore, conservation habitats at higher elevations in the Canadian Life Zone strategies should focus on protecting as many colonies (Hovanitz 1970, Ferris and Fisher 1971, Hammond, 22 23 1974, NatureServe 2006). Habitat for the bluish over the wet meadows and to improve the vigor and fritillary subspecies in Mexico is completely different; flowering of the herbaceous wetland plants. Cattle this subspecies is associated with dry pine woods, but browse young willow shoots following a burn, so the frequent rains during the adult flight (late August and combination of fire and grazing can prevent the willows September) maintain near bog-like conditions in the from forming dense, closed stands (Ellis 1989). needle and duff layer where larval foodplants (violets) grow (Ferris 1974). Nearby meadows are only used by Food habits adults to feed at concentrations of nectar sources that occur there (Ferris 1974). Based on differences in habitat Nectar plants preferences observed in these and other subspecies, Ferris (1974) cautions against using observations from The availability of suitable adult food resources one locality to “. . . make inferences concerning other throughout the adult flight period can be as important as regions without a thorough knowledge of all of the the presence of larval hostplants in determining whether environmental variables involved”, and suggests that an area can support populations of particular butterfly “. . . micro-environments may be the dominant factor species (Opler and Krizek 1984). This is especially controlling species distributions. . . .” true for long-lived butterflies such as members of the genus Speyeria. Most butterflies use nectar resources NatureServe (2006) describes habitat for the Great primarily to meet energy needs, but many long-lived Basin silverspot butterfly subspecies as “. . . streamside butterflies also use food resources for egg production meadows and open seepage areas with an abundance (Opler and Krizek 1984). Boggs and Ross (1993) found of violets in generally desert landscapes.” Ellis (1989) that for the Mormon fritillary (S. mormonia), adult food describes critical habitat components for the Great limitation did not have an impact on the lifespan or the Basin silverspot butterfly colonies at Unaweep Canyon mean mass of individual eggs, but fecundity decreased as “. . . the area of wet meadow, and sand bar willow dramatically. Individual females have a fixed number types, which generally support the greatest number of oocytes at the time they emerge, and they are laid, of foodplants violets, and provide the primary male resorbed by the female, or retained in the ovaries at the activity areas.” Ellis (personal communication 2000, time of death (Boggs 1986, Boggs and Ross 1993). In cited in NatureServe 2006) identified the following the Mormon fritillary, adult food limitation resulted habitat components for western Colorado Great Basin in re-allocation of resources away from reproduction silverspot butterfly populations: through the resorption of the oocytes (Boggs and Ross 1993). Adding protein to the diet of female regal v spring fed and/or subirrigated wetlands at low fritillaries increased both their fecundity (number eggs (7,500 ft. or less) elevation laid) and fertility (number eggs hatching), suggesting the importance of late-summer nectar sources to their long- v larval foodplant Viola nephrophylla term survival (Wagner 1995). Similar results should be expected for Great Basin silverspot butterflies, and a v wet meadows interspersed with willows and diverse assemblage of nectar sources may be needed other woody wetland species to ensure the continuous supply of nectar needed throughout their flight. v adult nectar sources (mostly composites) Great Basin silverspot butterflies utilize a variety A certain amount of disturbance may be of plant species as nectar sources, but thistles are necessary to maintain the complex of “wet meadows strongly favored (Scott 1986, Opler and Wright 1999). interspersed with willows and other woody wetland Ellis (1889) states that they prefer blue- and yellow- species” that provide optimal microclimates for the flowered composites. Documented nectar sources larval foodplant (bog violet) and adult nectar plants include native and introduced thistles, horsemint, and the Great Basin silverspot butterfly needs. Violets joe pye weed (NatureServe 2006). tend to be most abundant near the margins of the wet meadows and under shrubs, especially willows, and Larval foodplants they can be locally more abundant in grazed habitats (Ellis 1989). Violets are able to regenerate readily under Violets are the larval foodplants for all members grazed conditions, and grazing probably favors them of the genus Speyeria (Klots 1951, Hammond 1974, by reducing competition from other species. Periodic Ferris and Brown 1981), and the larvae of most burning can help to keep woody species from taking species can be reared on a variety of violet species in 22 23 the lab (Mattoon et al. 1971). Great Basin silverspot the oocytes (cells that undergo meiosis to produce an butterflies are found only at sites with bog violets (Ellis egg) (Kopper et al. 2001b). Factors leading to the onset personal communication 2000, cited in NatureServe of reproductive diapause are poorly understood (Sims 2006), the only confirmed larval food source for this 1984), but they may include long days and, to a lesser butterfly in the wild. Consequently, the bog violet may extent, high summer temperatures (Kopper et al. 2001b). be an essential habitat component of the Great Basin Termination of reproductive diapause and the initiation silverspot butterfly (Shields et al. 1969, Scott 1986, Ellis of oogenesis (meiotic division and maturation of the 1989). In fact, Shields et al. (1969) suggest that one way oocytes) coincide with shorter photoperiods and rapid to discover new populations would be to search sites increases in the levels of juvenile hormone (Sims 1984, with herbarium records for bog violet. Microhabitat Kopper et al. 2001b). This reproductive strategy may conditions for the bog violet include soggy soil and be an adaptation to the seasonal phenology of the larval shade, often under shrubs such as willows (Baird foodplants (Kopper et al. 2001b). Most violet species 1942). Bog violets appear to be more abundant and are senesced during the adult flight period for Speyeria to regenerate more readily in grazed habitats, perhaps species, and the fresh young leaves required by first due to reduced competition (Ellis 1989). They may also instar larvae are not available until the following spring benefit from periodic burning, which concentrates cattle (Wagner et al. 1997, Kopper et al. 2001b). Delaying grazing on the young willow shoots and helps to keep oviposition until early fall reduces the exposure of first the willow stands from becoming dense and closed instar larvae to the desiccating effects of the hot, dry (Ellis 1989). Fire and grazing can also have negative summer, and the overall time that the overwintering impacts on the butterflies and their habitat, so careful larvae are exposed to the elements (Sims 1984). guidelines should be followed when using them in areas with Great Basin silverspot butterflies (see Conservation Oviposition behavior section for more details). Oviposition is delayed in many Speyeria species, Breeding biology and while it likely occurs in the Nokomis fritillary and its subspecies, specific references documenting this Courtship and mating were not found in the literature. Great Basin silverspot butterflies lay eggs singly and haphazardly near their Nokomis fritillary males spend most of the day larval host plant (Scott 1986). Unlike most other violets patrolling the meadows or seeps where they occur in species, bog violet leaves are still green at the time search of females (Scott 1986). Ferris (1969) observed when eggs are laid (late summer to fall) (NatureServe nitochris fritillary mating behavior over a period of 2006), and olfactory cues given off by the plants might three summers (1966-1968) in Arizona (Gila and help females to select areas with violet concentrations Apache counties) and New Mexico (Catron County). (Hammond 1974). Hard substrates such as tree trunks, Males became active early in the morning as the dew downed logs, and willow stems appear to be preferred was drying (about 8:30 a.m. MST), and after feeding for oviposition, and they may provide additional briefly, they spent the rest of the morning patrolling protection for the small first instar larvae during winter close to the ground without feeding. Females emerged diapause (Ellis personal communication, cited in either from the tree cover on adjacent slopes or from NatureServe 2006). low shrubbery (mainly willows) adjacent to the streams about 1.5 to 2.0 hours later. They landed in the grass, Larval stages where they were discovered by the males. Paired courtship flights resulted, with attempted interference Great Basin silverspot butterfly eggs require by other males. All courtship and mating behavior was approximately 17 to 18 days to hatch under natural observed between 11:00 a.m. and 1:00 p.m. Similar conditions (Scott and Mattoon 1981), and first detailed behavioral observations for populations of the instar larvae enter winter diapause immediately Great Basin silverspot butterfly were not found. It is after hatching. Mortality is very high during this assumed that their behavior would be similar. life stage for most Speyeria species (Mattoon et al. 1971). The tiny, unfed larvae must survive the harsh Reproductive diapause is a characteristic life conditions of winter and then locate freshly emerging history trait for members of the genus Speyeria violet leaves before exhausting their limited reserves. (Edwards 1874, Edwards 1897, Sims 1984). Following Larval development resumes in the spring with the mating, females enter a prolonged period during which emergence of young violet leaves. There are six there is no further fat body depletion or maturation of larval instars, followed by the pupal stage. Scott and 24 25 Mattoon (1981) provide detailed descriptions for each Britten et al. (1994) conducted a study examining stage and data for total development time (oviposition population structure and genetic variability within to adult emergence) under laboratory conditions 13 populations of the Apache fritillary subspecies in (males = 61 days; females = 69 days) and estimates eastern California and Nevada. Their genetic analyses for natural conditions (males = 108 days; females = showed that mean heterozygosity estimates for those 122 days). However, they do not provide data for the populations were consistently lower than they were for development time for individual stages. other nymphalids. Heterogeneity tests and F-statistics suggested that the colonies were isolated from each other Demography and that even where populations were geographically proximate, they were likely to be drifting independently. Genetic characteristics and concerns Small effective population sizes and genetic drift were suggested as the most plausible explanations for the Habitat fragmentation tends to lead to smaller lost genetic variability. They also detected a number and increasingly isolated populations. Resulting of unique alleles in several populations, suggesting that genetic isolation can reduce population fitness because it may be necessary to conserve individual colonies to of genetic drift and lead to decreased heterozygosity preserve the evolutionary potential of the subspecies and elevated inbreeding coefficients (Britten and (Frankel and Soule 1981, Allendorf 1986). Glasford 2002). Williams et al. (2003) examined the genetic impacts of habitat fragmentation and isolation Great Basin silverspot butterflies also occur of populations by comparing genetic as small, isolated colonies within narrowly defined differentiation and diversity among non-fragmented ecological parameters. They are strong fliers and can (Great Plains), fragmented (Midwest), and historically move between isolated colonies within a continuous isolated (eastern) populations. The results suggested riparian zone (Arnold 1989, Fleishman 2002), but it is significant differentiation of the eastern Pennsylvania unlikely that they will disperse long distances between population resulting from long-term isolation, and highly isolated riparian systems. Williams (personal they supported predicted genetic effects of more communication 2006) collected preliminary genetic recent (at most since the 1860’s) habitat fragmentation. data for Great Basin silverspot butterfly and Apache Fragmented Midwestern populations showed increased fritillary populations in Colorado, Utah, and Nevada. differentiation and decreased genetic diversity when He did not see morphological evidence for a cline based compared to unfragmented Great Plains populations on wing color, but he did find a single base nucleotide (Williams et al. 2003). Allelic diversity and expected substitution in an mtDNA gene that followed a cline. He levels of heterozygosity were lower for Midwestern than noted that this is only “weakly suggestive evidence of a Great Plains populations and lowest for Pennsylvania, cline” and that data from more genes would be needed to but observed levels of heterozygosity were not always provide strong evidence for a cline. Williams (personal consistent with expected patterns, had higher variance, communication 2006) also suggested the following and were typically lower than expected levels based on preliminary conclusions based on the data: (1) there Hardy-Weinberg equilibrium (Williams et al. 2003). is very little genetic variation in these populations; (2) they either share a recent common ancestry (likely) or Brittnacher et al. (1978) conducted a study a lot of gene flow (unlikely); and (3) they have suffered examining genetic variation in 10 different Speyeria from many population bottlenecks. species and their subspecies in California and Nevada. The study included one population of the Apache Hybridization fritillary from Inyo County, California. They found that the average amount of genetic variation for those It is not unusual for many Speyeria species to Speyeria species was somewhat lower than the averages occur together (Hammond 1974, Brittnacher et al. that have been reported for other Lepidoptera, but the 1978), but Brittnacher et al. (1978) state that despite this amount of genetic variation was significantly lower multispecies sympatry, hybrids between those species for the Apache fritillary, which had the lowest levels are “exceedingly rare or nonexistent.” More recently, of heterozygosity. Colonies of Nokomis fritillary at least two hybrids have been documented between subspecies tend to be small, local, restricted to a different subgenera (Speyeria [Semnopsyche] and relatively narrow elevational range, and susceptible to Speyeria [Speyeria]). Scott (1981) captured an apparent

occasional severe population declines; consequently, F1 male hybrid between S. nokomis apacheana and S. low levels of heterozygosity are not unexpected. cybele leto near Bridgeport, Mono County, California.

24 25 Pure populations of both species were also caught at the dispersal. Therefore, it is best to assume that long- site. Hammond (personal communication, cited in Scott distance dispersal between isolated riparian systems is 1981) has a natural female hybrid between S. cybele not likely, and if an entire system of colonies within a pugetensis and S. hydaspe rhodope. The occurrence given riparian system is extirpated, the probability that of both male and female hybrids between species they will be repopulated is low. Because Great Basin previously thought to be in separate subgenera led Scott silverspot butterflies have only a single generation per (1981) to speculate that hybridization among Speyeria year, it is also anticipated that populations will recover species may actually be fairly frequent, but that it goes more slowly following depression than species with undetected due to the similarities between species and several generations per year would (Swengel 1996, the difficulty identifying them. No documentation for Panzer 2002). Great Basin silverspot butterflies hybridizing with other species was found. However, it is quite likely that Long-lived butterflies (e.g., Speyeria species) hybridization between subspecies does occur where use food resources for egg production (Opler and they come together. This is especially true for the Great Krizek 1984), necessitating a constant supply of nectar Basin silverspot butterfly and the Apache fritillary in to maintain maximum fecundity. The availability of Utah where there is an apparent hybrid blend zone diverse nectar sources throughout the adult flight may (Swisher and Morrison 1969, Ferris and Fisher 1971). be a critical factor limiting fecundity. Litter buildup can limit population growth by making it more difficult Ecological influences on survival, reproduction, for first instar larvae to locate foodplants, lowering the and population growth abundance and nutritional quality of the foodplants, and reducing flowering of nectar sources (Dana 1991). Great Basin silverspot butterflies require Limited grazing, haying, or fire can be beneficial by streamside meadows and seepage areas with an removing litter and reducing competition with other abundance of their larval foodplant (bog violet), and vegetation. Grassland/wetland communities are likely to the availability of a constant supply of nectar sources have similar responses to the build up of litter, whether (mostly composites) throughout the adult flight. The size they are in the Rocky Mountains or on the prairies. The and quality of these wetland communities, healthy bog responses of larvae to the physical challenges posed by violet populations, adequate adult nectar sources, and navigating through the litter may be similar for different the quality of the riparian corridor within which they butterfly species. occur are all important factors that can limit the size of Great Basin silverspot butterfly populations in a given Extreme weather conditions can pose a threat to area. These habitat types tend to be small and isolated, Great Basin silverspot butterflies, and the impact can resulting in small populations with limited reproductive be expressed over a large geographic area. Climatic potential, making it more likely that a catastrophic warming and droughts could affect the butterflies by event will affect the entire population. Consequently, it altering the hydrology of wetlands. During the adult is important to protect multiple colonies within an area flight, severe storms can cause direct adult mortality, to buffer the entire population from likely extinctions of and prolonged periods of cool temperatures, overcast individual colonies. skies, and rain can limit reproduction by limiting adult activity. Disease, parasitism, and predation can Adult movement associated with mate-seeking also influence the survival of each stage in the life and courtship tends to be local within the small isolated cycle. Actual observations and data on stage specific wetland communities where the colonies occur, but both mortality factors and the probabilities of completing sexes move more extensively along the riparian corridor each stage in wild populations would be helpful but are in search of nectar sources (Ellis 1989). Mark-recapture not available. data indicate movement between colonies within a riparian corridor (Arnold 1989, Fleishman et al. 2002), Selection of oviposition sites by the females and this exchange of individuals could mitigate the determines where, and in what type of habitat, the next short-term extinctions of individual colonies and ensure generation of butterflies will be produced (Hammond the long-term survival of the overall population (Ellis 1974). Females lay eggs singly and haphazardly near 1989). Great Basin silverspot butterflies do not migrate, the larval host plants (Scott 1986). Hard surfaces (e.g., but they are strong fliers. The adults might be capable tree trunks, downed logs, willow stems) are preferred of dispersing greater distances (e.g., between riparian oviposition substrates, and they may provide additional corridors), but this is more difficult to document, protection for the small first instar larvae during winter and no evidence was found to confirm long-distance diapause (Ellis personal communication, cited in 26 27 NatureServe 2006). Larvae overwinter as first instars, Competition and these tiny larvae must contend with surviving harsh winter conditions, disease, parasitoids, direct and The larvae of all Speyeria species feed on violets, indirect mortality from fires that consume the vegetation and many species are widely sympatric (Hammond where they are sheltered. They must then locate freshly 1974), so they might be expected to compete for larval emerging violet leaves in the spring before exhausting foodplants. Competition with other Speyeria (e.g., their limited reserves. Once they locate a foodplant, [S. aphrodite]) has been postulated the larvae do not move far from that location, and their for the decline of regal fritillaries in the East (Wagner movements only account for very localized dispersal et al. 1997), but there is very little field evidence within a colony. Because larval development rates are to confirm this (Zercher et al. 2002). Hammond proportional to temperature, unusually cool conditions (1974) suggests that sympatric Speyeria may avoid can slow growth rates and prolong exposure to mortality interspecific competition through niche segregation. factors (Dana 1991). Humid conditions have been However, some species may be ecologically dominant associated with increased susceptibility to bacterial and are able to occupy the most favorable habitats septicaemia in some skipper species (MacNeill 1964), while forcing other species to use less favorable but examples of this were not found for Great Basin habitats (Hammond 1974). No documentation was silverspot butterflies. found for significant effects of competition with other sympatric Speyeria on the dynamics of Great Basin Community ecology silverspot butterfly populations. However, the effects of competitive interactions are poorly understood and Disease, parasitism, and predation merit further study.

Disease, parasitic organisms, and predators can Envirogram cause mortality during each stage in the Great Basin silverspot butterfly life cycle (NatureServe 2006), Andrewartha and Birch (1984) define the and the spread of a parasitoid or pathogen has the environment of an animal as “. . . everything that potential for rangewide impacts (Wagner et al. 1997). might influence its chance to survive and reproduce.” Parasitoids or pathogens may have played a part in the Important ecological relationships that are known to decline of eastern regal fritillary populations, but there affect Great Basin silverspot butterflies are depicted is little or no direct field evidence for this (Zercher et graphically as an envirogram in Figure 8. The “centrum” al. 2002, NatureServe 2006). Disease has proven to be includes direct influences that are the proximate causes an important mortality factor in attempts to rear regal of the Great Basin silverspot butterfly’s condition; fritillaries in the lab. The polyhedrosis virus (NPV) these are grouped into positive (e.g., resources and can be transmitted from females to offspring in eggs, mates) and negative (e.g., malentities and predators) or between individuals through frass (excreta); in one influences. The “web” includes distal causes of the captive group, this virus caused 80 percent loss (Wagner Great Basin silverspot butterfly’s condition; they act et al. 1997). Mortality rates were also high (50 percent) indirectly by modifying the centrum and can be one for 12 field-collected regal fritillary larvae observed in a to several steps removed from it (e.g., 1st to nth order feeding behavior study in Kansas (Kopper et al. 2001a). modifiers) (Andrewartha and Birch 1984). Important Three of those larvae were parasitized by Hymenoptera, resources for the Great Basin silverspot butterfly are and three others died from unknown causes. Predation larval foodplants and adult nectar sources. Adults also by birds or invertebrates is a mortality factor, but require an adequate moisture supply from nectar plants generally, the impact on healthy butterfly populations or wet soil (e.g., pond margins). Suitable high quality is not thought to be significant (Dana 1991). During wetland communities associated with riparian corridors 15 days of fieldwork at Rowe Sanctuary in Nebraska, are essential to provide these resources, and suitable no evidence of bird predation of regal fritillaries was soil types, hydrology, rainfall, grazing, and fire combine noted (Nagel et al. 1991). No documentation was found to influence the type and quality of the communities. for diseases, parasitic organisms, or predators that are These habitats also support species that are parasites specific to the Great Basin silverspot butterfly. Stage or predators, so conditions that favor those species specific data on the impacts of disease, parasitism, and will have an indirect, negative effect on Great Basin predation were also lacking. silverspot butterflies. Malentities include habitat loss

26 27

BASIN GREAT BUTTERFLY SILVERSPOT

CENTRUM and fragmentation and fragmentation (spiders, insects, birds) insects, birds) (spiders, Food (adult): forbes (insects, viruses)

Food (larval): bog violet

Larvae predation/parasitism: predation/parasitism: Larvae

Direct mortality mortality Direct Adult predation: predation: Adult MALENTITIES PREDATORS PREDATORS (nectar – nutrients/moisture) RESOURCES

(especially larvae) Adult/Immature stages Adult/Immature (insects) Egg predation/parasitism: predation/parasitism: Egg 1 ccession Habitat loss/degradation

Seep, Springs, Overgrazing

Woody su Overgrazing

Exotic speciesExotic Agricultural

Extreme weather Extreme Rain/ponded water moisture/minerals

Wet meadows,

Riparian Habitat Prescribed fire Altered hydrology

Development

Seep, Springs,

Riparian Habitat Habitat Riparian Wet meadows, Wet meadows, 2 WEB

Wet meadows,

Fire

Riparian Habitat Riparian Habitat

Water Grazing Soil

Seep, Springs, Fire Soil

Grazing

Water 3 Figure 8. Envirogram for the Great Basin silverspot butterfly.

Water

Soil

Grazing

Fire

29 or degradation resulting from hydrology, overgrazing, fritillary subspecies depend on a constant source of agriculture, mining, development, woody succession, water (e.g., streams, springs, seeps) throughout the and exotic invaders. Direct mortality of larvae results summer (Hovanitz 1970, Hammond 1974, Hammond from prescribed fires, overgrazing, or extreme weather and McCorkle 1983). Activities that alter hydrology events. Activities such as fire and grazing can have are likely to threaten the wetland communities and both positive and negative effects, and they must be butterflies. Water diversion and storage projects are used with caution to maximize positive impacts and to among the biggest threats (Ferris and Brown 1981, minimize negative impacts. Hammond and McCorkle 1983). Water diversion to the City of Los Angeles eliminated much of the natural CONSERVATION water flow in Owens Valley, Inyo County, California, the presumed type locality for the Apache fritillary Threats (Brown 1957, Ellis 1969, Hammond and McCorkle 1983). Natural events, such as general warming, or Habitat loss/conversion crustal movements due to the 1972 earthquake, may have also influenced the water table there (Ellis 1969). Great Basin silverspot butterflies are “very tightly restricted” (Hammond and McCorkle 1983) Logging, road construction, and development to streamside meadows and seepage areas with an can all affect hydrology. Cary and Holland (1992) abundance of their larval foodplant (bog violet), and the cite an example in the Sacramento Mountains of New availability of adult nectar sources (mostly composites) Mexico, where tree removal in the early 20th century during the adult flight. These habitat conditions are resulted in more rapid runoff of storm water, resulting scarce in the arid Southwest, and tend to occur as small, in extensive gullying and channel downcutting, leading widely separated and isolated spots associated with to lowering of the water table. As a result, several permanent sources of flowing water within the arid miles of streamside wet meadows that had supported landscape. Cary and Holland (1992) suggest that during large populations of bog violet were converted into dry the Pleistocene Ice Ages, the southwestern United States meadows incapable of supporting Nokomis fritillaries. was much wetter than it is today, and that wetland and Capping springs (NatureServe 2006) and draining riparian habitats and their associated fauna (e.g., Great wetlands for cultivation (Cary and Holland 1992) are Basin silverspot butterflies) would have been much also threats. more ubiquitous. Because of the drier post-Pleistocene climates, those wetland communities and their fauna Grazing effects became restricted to small, widely separated and isolated fragments of their former ranges, surrounded by an arid Fleishman et al. (2002) describe livestock grazing landscape. The advent of human activities such as as “the most widespread form of human-generated housing developments, modifications to the hydrology disturbance.” Short-term negative impacts include (e.g., water diversion projects; draining wetlands), and reduced nectar availability and vegetation cover, and mineral extraction (e.g., gravel mining) have resulted long-term impacts include soil compaction and reduced in further habitat loss and fragmentation. Ellis (1989), water infiltration, which can lead to a loss of larval host for example, visited a site along the Animas River near plants and invasion by non-native grasses (Fleishman Durango in La Plata County, Colorado in 1986 and et al. 2002). Excessive livestock grazing can be a found that it had been severely disturbed by gravel serious threat to Great Basin silverspot butterflies and mining. Housing developments are also a major threat their habitat (Hammond and McCorkle 1983, Cary in this area, and at least one population in the county and Holland 1992), but light or moderate grazing may has been eliminated (Opler personal communication actually benefit the butterflies by giving their larval 2000, cited in NatureServe 2006; Williams personal foodplants a competitive advantage. Ellis (1989) communication 2006). Habitat loss and fragmentation noted that at the Unaweep Canyon site, Great Basin resulting from such activities constitute the greatest silverspot butterflies continue to coexist with current historic, current, and future threats to the long-term livestock grazing practices, and have even persisted survival of the Great Basin silverspot butterfly. in areas that have been heavily grazed for the past 100 years. Bog violets appear to be “locally more abundant” Altered hydrology in the grazed habitats, perhaps because grazing can help reduce competition with other plant species and The wetland communities and larval foodplants improve conditions for violets to regenerate (Ellis (bog violet) required by the various Nokomis 1989). Ellis (1989) also noted that cattle browse young 29 willow shoots in pastures that have been burned, which Prescribed burning and wildfires helps maintain more open willow stands. The timing and intensity of grazing are critical factors, along with Ellis (1989) observed that at the Unaweep other site-specific conditions; sustained and intense Canyon site, nearly all the streamsides dominated by grazing degrades the habitat and is not recommended sandbar willow (Salix exigua) had been periodically (Arnold 1989; Ellis personal communication, cited in burned. Ranchers told him that they burn those areas NatureServe 2006). Ellis (1989) examined the Mount because cattle browse the young willow shoots during Sneffels, Ouray County site in September of 1989 and winter, and burning improves grazing by opening up the found that it was abusively overgrazed, and most of the herbaceous understory. Other woody species associated willow thickets had been stripped by year-round horse with wetlands at Unaweep Canyon (e.g. alder [Alnus grazing. Hammond and McCorkle (1983) observed that tenuifolia], river birch [Betula fontinalis], hawthorn excessive livestock grazing in 1976 severely impacted [Crataegus spp.], and shiny willow [S. lucida]) are meadows in the Sacramento Mountains of New Mexico less fire tolerant and become restricted to the wettest and the White Mountains of Arizona. Mikesic (personal portions of sites that are burned regularly (Ellis 1989). communication 2006) has observed that grazing (e.g., Prescribed burning can be used to maintain the complex cattle, horses, sheep) as it is typically practiced, is of wet meadows, willows, and other woody wetland generally a threat. He notes that while the violets might species that provides optimal microclimates for the persist, nectar sources are often negatively impacted. larval foodplant (bog violet) and adult nectar plants the Great Basin silverspot butterfly needs. Direct short- Exotic species term mortality from burning might be heavy for the Great Basin silverspot butterfly (NatureServe 2006), Great Basin silverspot butterfly colonies and but both the butterfly and its larval foodplant appear their wetland habitats often exist as small and isolated able to survive, and perhaps even benefit from the fragments within riparian corridors that are surrounded periodic burning of the sandbar willows (Ellis 1989). by altered or degraded habitats where exotic species are Similar results have been observed in native prairie abundant. Ellis (1989) states that “noxious herbaceous ecosystems east of the Rocky Mountains. Huebschman weed invasion probably represents the most serious, and and Bragg (2000) examined the impact of a late spring most intractable ecological threat to the maintenance of burn on a regal fritillary population at Nine-mile Prairie native plant species diversity within these wetlands.” in Nebraska; the butterflies have persisted there with a Aggressive perennial species such as Canada thistle 3- to 4-year burn frequency since 1979. Regal fritillaries (Cirsium arvense) and leafy spurge (Euphorbia esula) were observed throughout the study area in the pre-burn can replace the diverse native communities with dense year, declined significantly in the burn unit during the monocultures, and are very difficult to control. However, first part of the post-burn flight, and then recovered some adventive species (e.g., bull thistle [C. vulgare], to the same numbers as the unburned unit later in the and burdock [Arctium minus]) may actually benefit the season. Other studies have consistently shown that Great Basin silverspot butterflies by providing nectar aggressive fire management programs tend to depress sources within and near the wet meadow/sandbar willow prairie-specialist butterfly populations (Swengel activity areas (Ellis 1989). Tamarisk (Tamarix spp.; 1996, Swengel and Swengel 2001). Recent (1999- also known as saltcedar) and Russian olive (Eleagnus 2003) upward trends for regal fritillary populations at angustifolia) are aggressive exotic woody species that monitored sites in Wisconsin suggest more moderate can be a serious threat by entirely altering wetland and burn regimes, and permanent non-fire refugia may be riparian vegetation communities (Ellis 1989). benefiting those populations (Swengel 2004).

Pesticides Negative impacts of fire can include direct mortality of larvae in the litter layer during dormant Indiscriminant use of insecticides for pest control season burns (Dana 1985, 1991) and indirect mortality on rangeland or adjacent cropland can be a major direct of larvae resulting from increased exposure to extreme threat to Great Basin silverspot butterflies. Broadcast winter conditions after fall burns remove the insulating spraying of herbicides, which usually targets dicots, can litter layer. Improperly timed burns can also temporarily also affect their populations indirectly by eliminating limit the availability of critical resources (e.g., larval larval foodplants and important nectar sources. foodplants, nectar sources) immediately following the

30 31 burn or alter their phenology (e.g., delayed blooming Conservation Status of the Great Basin due to a late spring burn). Given these factors, it should Silverspot Butterfly in Region 2 be assumed that extensive (e.g., burning all or most of the habitat in an area at one time) or frequent (e.g., The Great Basin silverspot butterfly has every one to two years) fires are likely to negatively experienced significant declines in Colorado, the only affect butterfly populations. Managers need to be aware state in Region 2 where it occurs. There are historic of the positive and negative impacts of fire, and their records from 11 counties in western and south- combined impacts on long-term survival of Great Basin central Colorado, but there may only be two to five silverspot butterfly populations. extant populations in as many counties (Colorado Natural Heritage Program 2004, Williams personal Over-utilization for commercial, recreational, communication 2006). The Unaweep Canyon population scientific, or educational purposes in Mesa County is probably the largest and most secure population in Colorado, and the second largest Collecting rarely has an impact on insect population for the subspecies (Ellis 1989). Surveys populations due to their high reproductive capabilities indicated an order of magnitude increase in size for the and should not generally be a problem for most population between 1979 and 1989 (Arnold 1979, 1989), butterflies (Pyle et al. 1981, Hammond and McCorkle and its status was described as viable but vulnerable 1983). Destruction of habitat and/or food resources is due to small colony size (Ellis 1989). More recently, usually the primary factor responsible for population the Colorado Natural Heritage Program (2005a) has declines (Hammond and McCorkle 1983). However, assigned the population an element occurrence status populations that are already depressed or concentrated rank of A (excellent estimated viability). The prognosis in small habitat fragments, like Great Basin silverspot for all other populations in the state is uncertain. There butterflies, can be more sensitive to overcollecting are seven other element occurrence records in the (NatureServe 2006). In addition, amateur and Colorado Natural Heritage Program database. The commercial collectors both value this species. When status rank for one is C (fair estimated viability; last females are removed before they have a chance to observed in 1999), but Great Basin silverspot butterflies reproduce, populations can be further reduced. However, have not been seen at the other six sites in over 20 years limited collecting for scientific documentation should (Colorado Natural Heritage Program 2005a). Ehrlich not affect populations of this species. There is no federal (1983) found a new population along the Green River or state legal protection for Great Basin silverspot in Dinosaur National Monument, Moffat County, and in butterflies, but it is usually necessary to get permission 1997, Williams (personal communication 2006) found to collect in protected areas. a population closer to the Utah border in Dinosaur National Monument. Environmental factors These trends suggest an urgent need to determine Extreme weather conditions can pose a threat to the status of known populations, to search for new Great Basin silverspot butterflies, and the impact can populations in areas with Great Basin silverspot be expressed over a large geographic area. The tiny butterfly habitat and larval foodplants, and to implement first instar larvae are susceptible to extreme winter a conservation strategy to protect all known extant weather, late spring hard frost, severe storms, or populations. Development, water diversion, sustained cool damp conditions. Humid conditions have been and intense grazing, and weed infestations continue to associated with increased susceptibility to bacterial threaten existing populations and their habitat (Colorado septicaemia in some skipper species (MacNeill 1964), Natural Heritage Program 2005b). National Forest but examples of this were not found for Great Basin System and other public lands are a critical component silverspot butterflies. Cooler than normal temperatures of any conservation strategy, but many colonies are on could prolong exposure to mortality factors by slowing private land, so it will also be important to work with larval development rates (Dana 1991). During the adult private landowners to encourage appropriate land use flight, severe storms could cause direct adult mortality, practices. Grand Mesa/Uncompahgre/Gunnison, San and prolonged periods of cool temperatures, overcast Juan, Rio Grande, and White River national forests in skies, and rain could limit reproduction by limiting Colorado should have habitat that could support Great adult activity. Warming trends and severe droughts Basin silverspot butterfly populations. Unfortunately, could affect the butterflies by altering the hydrology of there are very few data documenting their occurrence or the wetland communities on which they depend. status on those lands.

30 31 Potential Management of the Great Tools and practices Basin Silverspot Butterfly in Region 2 Habitat management Implications and potential conservation elements Management for butterflies is often incidental to management focused on restoring the native plant Habitat for the Great Basin silverspot butterfly communities where they occur. While Great Basin includes streamside meadows and seepage areas with an silverspot butterflies should benefit indirectly from abundance of their larval foodplant, the bog violet, and the improved habitat, managers need to be more adult nectar sources during the adult flight. These habitat aware of the species’ specialized habitat requirements conditions occur in widely separated and isolated spots and vulnerabilities to specific management activities. associated with flowing water in an arid landscape, so Management should focus on meeting those habitat the butterfly colonies also tend to be small and isolated. requirements (e.g., microclimates that favor larval Great Basin silverspot butterflies are strong fliers, and foodplants, increased flowering of nectar plants while they can move between isolated colonies within throughout the adult flight, protection for overwintering a continuous riparian zone, it is unlikely that they will larvae), and mitigating direct (e.g., mortality of larvae disperse long distances between highly isolated riparian during fires; mortality of eggs, larvae, and pupae due systems. Historic loss, degradation, and fragmentation to trampling by cattle) and indirect (e.g., unfavorable of wetland communities and the riparian corridors shifts in community composition or structure; untimely where they occur have contributed to the decline and elimination of nectar sources; removing protective current vulnerability of Great Basin silverspot butterfly cover for overwintering larvae) harmful effects of the populations. To prevent further losses, crucial habitat management. Standard habitat management tools and (e.g., riparian wetland communities with bog violet) practices are discussed below in the context of their needs to be identified, protected, and managed to impact on Great Basin silverspot butterflies. maintain or improve its size, quality, and connectivity. Management should be directed toward controlling, Prescribed burning: Ranchers use prescribed but not eliminating, native woody species (e.g., fire to improve grazing by opening up the herbaceous preventing willows from forming dense, closed stands), understory. It can also be a valuable tool for maintaining eliminating exotic species, increasing the vigor of larval habitat used by Great Basin silverspot butterflies, foodplants, and maintaining adequate nectar sources. enhancing their larval foodplant populations, and Because small isolated Great Basin silverspot butterfly increasing the flowering of important nectar sources. populations are more vulnerable to events that they However, it is important to understand the interactions might have survived when the natural landscape where between positive and negative effects of fire, and they occur was more intact, management activities their combined impact on long-term survival so that should be designed carefully to avoid exacerbating appropriate plans can be developed and implemented. those vulnerabilities. The timing, intensity, extent, and Negative effects of fire can include direct mortality of duration of management activities, such as grazing larvae in the litter layer during dormant season burns and prescribed fire, should to be adapted to ensure the (Dana 1985, 1991), and indirect mortality of larvae availability of critical resources (e.g., nectar plants and due to increased exposure to extreme winter conditions larval foodplants) when they are needed, and to mitigate after fall burns remove the insulating litter layer. Burns any direct mortality that might result. can also temporarily limit the availability of critical resources immediately following the burn (e.g., larval The status of Great Basin silverspot butterfly foodplants after spring burns, nectar sources after populations on National Forest System lands in Region summer burns) or by altering their phenology (e.g., 2 is not well documented. Some of the top priorities delayed blooming due to a late spring burn). should be to inventory units with habitat and the larval foodplant, to determine the status and distribution of It should be assumed that overly extensive (e.g., populations within those units, to implement appropriate burning all or most of the habitat in an area at one conservation practices (see below), and to monitor the time) or excessively frequent (e.g., every one to two results so that management plans can be adapted as years) fires will negatively affect butterfly populations. needed to maintain and/or enhance the size and health When burning is done, it should be assumed that there of the populations. will be 100 percent mortality in the burned area, or that

32 33 essential resources may be temporarily unavailable. stocking rates, modifying grazing regimes (e.g., season- Consequently, it is important that adequate areas are long vs. rotational; patch-burn), and managing water left unburned to serve as recolonization sources, and resources to avoid concentrating activity in critical that return intervals of fires should be long enough habitat areas (Royer 2002, 2003). (e.g., 3 to 6 years for prairies) to allow for full recovery of populations between burns. The management Light to moderate grazing has been shown to guidebook developed for Great Plains butterflies benefit Great Basin silverspot butterflies by giving a (Moffat and McPhillips 1993) and numerous studies competitive advantage to their larval foodplants (Ellis focused on native prairie ecosystems east of the Rocky 1989), but sustained and intense grazing can degrade Mountains (e.g., Dana 1989, Dana 1991, Swengel 1996, habitat and eliminate nectar sources during the adult Panzer 1998, Swengel 1998, Swengel and Swengel flight. Different grazing regimes may have decidedly 1999, Swengel and Swengel 2001, Panzer 2002) different impacts, and recent research suggests that can provide general guidelines for using prescribed the combined effects of integrated fire and grazing fire as a management tool for Great Basin silverspot systems (e.g., patch-burn grazing) may be significant butterflies. However, studies examining specific fire (Fuhlendorf and Engle 2001, Helzer and Steuter 2005). impacts on Great Basin silverspot butterflies and their Cattle tend to graze preferentially in the burned areas, habitat are needed. resulting in “patchy” grazing patterns. The combination of fire and grazing is also an effective way to control the Haying or mowing: Ranchers often harvest willow stands. Very little rigorous research examining native hay for their cattle from wetlands and grasslands grazing impacts has been done, so any grazing regime along riparian corridors that support Great Basin should be implemented with caution. Populations of silverspot butterflies (Ellis 1989). This practice can have Great Basin silverspot butterflies and their essential many of the same benefits as light to moderate grazing habitat components should be monitored, so that or periodic burning (e.g., preventing the accumulation the intensity, timing, and duration of grazing can be of excessive litter and succession to woody species). adjusted in response to observed impacts on them. Using native hay harvested from these sites also has the advantage of reducing the amount of weed seed Chemical control of exotic species and woody that might be brought into an area via imported hay. vegetation: Selective applications of herbicides Managers might want to utilize haying or mowing as can be an effective way to control exotic species an alternative to grazing and fire, or in combination to or invasive woody vegetation. Cutting and treating enhance their effectiveness. As with any management stumps of woody vegetation with a systemic herbicide practice, the impact on Great Basin silverspot butterflies is an effective way to prevent suckering. Because will depend on the frequency, timing, intensity, and treatment is localized, damage to the surrounding extent of haying or mowing. If it is done too often vegetation may be minimized. However, the high (e.g., two or more times per year) or during the adult water table in butterfly habitats might make it more flight period (e.g., mid-July to mid-September), it will difficult to apply the herbicide safely. There may be have a negative effect by eliminating nectar sources. If legal restrictions on the types of herbicides that can be an area is mowed too short, the effects on developing used in the riparian wetland communities where Great eggs or larvae could be negative, so if possible, at least Basin silverspot butteries are found, and extra caution 6 inches of stubble should be left. No matter what the should be exercised when using them. Ellis (1989) does timing or intensity of the mowing, there will always be not recommend using herbicides for willow control species that are negatively impacted. Therefore, just as because concentrations needed to kill the willows are with burning, only a portion of a site (e.g., no more than so high that other more sensitive species would be one-third to one-half) should be hayed or mowed in a devastated. Spot spraying of perennial exotic species given year. might be necessary, but this should always be done as a last resort and with extreme caution to avoid damaging Grazing: Livestock grazing is a common land use the surrounding vegetation. Non-persistent herbicides practice on National Forest System lands; consequently, (e.g., glyphosphates) are preferable to more persistent it is important to understand the impacts of grazing on herbicides (e.g., picloram), but they may not be as vegetation communities that Great Basin silverspot effective. Broadcast spraying with broadleaf herbicides butterflies colonize. Grazing should be managed to is a common practice in range management, but this is minimize negative impacts on the abundance of larval not recommended for native systems since native forbs foodplants or adult nectar sources. The spatial and are killed along with the targeted exotics. temporal effects of grazing can be managed by adjusting 32 33 Biological control of exotic species: Biological Good data exist for the population at Unaweep control provides an alternative to the use of non- Canyon (Arnold 1979, Arnold 1989, Ellis 1989), and selective, persistent herbicides for treating aggressive a first priority should be to continue those studies and perennial exotic weeds such as tamarisk and leafy use them as a model for developing inventory and spurge. The control agents are tested rigorously to make monitoring programs at other sites. Transect surveys are sure they are “safe” for native species, but it is still a generally the most efficacious method for monitoring good idea to research any biological control options populations, but since colony sizes tend to be small thoroughly before approving them for use on native (i.e., 5 to 20 acres) and well defined, wandering timed ecosystems. Chinese leaf beetles (Diorhabda elongata) surveys within each colony may also be effective. are a potential control agent for tamarisk, and they Mark-recapture studies, such as those by Arnold (1989) have been tested extensively to determine their host at Unaweep Canyon, provide valuable information on specificity (Colorado Department of Natural Resources the metapopulation dynamics among colonies along 2004). Tamarisk species were the only plants on which a riparian corridor. They need to be implemented at a the beetles feed and reproduce, and since no native scale that will provide better data on the exchange of relatives of tamarisk occur in the United States, they individuals throughout the complex of colonies along were approved for release in 2005 (Bean 2005, Norton the riparian corridor. The second priority should be to and Lane 2005). Leafy spurge is also a prime candidate update the status of historic populations, and the third for biological control. The most effective control agents priority should be to identify sites where Great Basin for leafy spurge include several species of flea beetle silverspot butterfly habitat and its larval foodplant (Aphthona spp.), and they have proven to be much more (bog violet) co-occur, and search for new populations cost-effective than chemical control methods. at those sites. Checklist surveys at both the historic and potential sites are needed first, and at those sites Inventory and monitoring where populations are identified, monitoring programs modeled after the methodology that works best at the Pollard transect surveys (Pollard et al. 1975, Unaweep Canyon site should be implemented. Current Pollard 1977, Pollard 1982, Pollard and Yates 1993) are Global Positioning System (GPS) technology makes it the standard butterfly monitoring methodology adopted fairly simple to navigate defined survey routes and to by many lepidopterists. They involve surveying fixed map the distribution of the butterflies and their preferred routes (transects) using standardized protocols (e.g., habitat areas. survey speed, time of day, weather) and have the advantages of being fairly simple and easily replicated. Information Needs The results are relative abundance values for each species that can be used to track trends over time. Inventory and monitoring Absolute population estimates can be useful, but they involve much more labor-intensive mark-recapture There is very little information available for the methods (Ehrlich and Davidson 1960, Brussard 1970). occurrence, distribution, and abundance of Great Basin The “checklist” survey is an alternate methodology in silverspot butterflies on National Forest System lands which the survey route is not fixed (Royer et al. 1998). within Region 2. Several USFS units are identified in this It involves an unrestricted comprehensive search, and assessment as having Great Basin silverspot butterfly has the advantages of being fairly simple and focusing populations (Grand Mesa/Uncompahgre/Gunnison the effort in habitat for the target species. Royer et al. National Forest), or as likely to have populations (San (1998) compared the “checklist” and “transect” methods Juan and Rio Grande national forests). These units to determine which would be the most efficacious. should be evaluated first to determine if they have The number of individuals counted per unit time was Great Basin silverspot butterfly habitat (e.g., permanent significantly higher for the checklist method, but there spring-fed meadows, seeps, marshes, and boggy was no significant difference between the methods for streamside meadows associated with flowing water) and the number of species observed per unit time. However, the larval foodplant, the bog violet. Soils and vegetation the checklist method was better at capturing sedentary, maps can be used to identify areas with habitat, and habitat-specialist species (e.g., many lycaenids and herbarium records can be used to narrow the search to hesperiids). They concluded that the checklist method sites where the habitat and larval foodplant co-occur. was better for obtaining an initial site-specific butterfly Those sites should be surveyed to determine if Great species list, but that the transect method was better for Basin silverspot butterfly populations are present, and if long-term monitoring. they are, to document their distribution and abundance

34 35 within the sites. Regular monitoring programs should Fire management impacts be implemented for all known populations, and data should be used to develop, implement, and evaluate Many of the studies examining fire impacts on policy and management decisions for those sites. butterflies and invertebrates have focused on native prairie ecosystems (Dana 1989, Dana 1991, Swengel Grazing impacts 1996, Panzer 1998, Swengel 1998, Swengel and Swengel 1999, Swengel and Swengel 2001, Panzer Light to moderate grazing is generally thought to 2002). They provide general principles that can be benefit Great Basin silverspot butterflies and their larval applied to fire management in the riparian grassland foodplants while heavy grazing is considered a threat. and wetland systems where Great Basin silverspot However, there is a need for more rigorous research butterflies occur. However, there is still a need to conduct examining those impacts. This is especially relevant research examining the short- and long-term effects of to National Forest System lands since so many of them prescribed burn programs on the butterfly populations contain grazing allotments. and the interaction between prescribed burning and other management options (e.g., grazing and haying). Specific questions that need to be addressed are the appropriate size (relative to the total area), frequency, and timing of burns, and the value of “permanent non- fire refugium” (Swengel 2004).

34 35 DEFINITIONS

Canadian Life Zone – southeastern Canada and moderate altitudes in the mountains to northwestern Georgia in the east and to New Mexico in the west; includes fir-spruce-tamarack and some pine, aspen-maple-birch-alder-hemlock (Scott 1986). Chorion – outer covering of an insect egg. Daily flight period –time period during each day when adult butterflies are active. Diapause – a period of suspended growth and development. Diurnal – active during the daytime, rather than at night. Extant – populations that are still in existence; not lost, destroyed or extinct. Extirpate – to destroy completely or exterminate a population. Glyphosphate – a general use, non-persistent systemic herbicide. Habitat capability – the overall capacity of the habitat to support populations of the target species, including habitat components such as size, quality, fragmentation, isolation, etc. Instar – insect stages between molts; larval stages in this paper. Larva – immature stage between egg and pupa in insects with complete metamorphosis. Metapopulation – localized group of smaller populations living in separate habitat patches (Levins 1970, Mason 2001) Oocyte – cell that will undergo meiosis to produce an egg. Oviposition – laying eggs; especially in insects with an ovipositor (egg laying structure). Picloram – a persistent systemic herbicide in the pyridine family of compounds, which is used to control woody vegetation. Univoltine – having a single generation per year. Upper Sonoran Life Zone – western United States; includes pinyon-juniper woodland, chaparral, arid sagebrush, and dry prairie (Scott 1986).

36 37 REFERENCES

Abramson, K. 2005. Wildlife Biologist, Planning, Grand Mesa, Uncompahgre and Gunnison National Forests. Grand Junction, CO. Allendorf, F.W. 1986. Genetic drift and the loss of alleles versus heterozygosity. Zoological Biology 5:181-190. Andrewartha, H.G. and L.C. Birch. 1984. The ecological web: more on the distribution and abundance of . University of Chicago Press, Chicago, IL. 506 pp. Arnold, R.A. 1979. Unaweep Seep butterfly study. Submitted to U.S. Bureau of Land Management, Grand Junction, CO. Arnold, R.A. 1989. Unaweep Seep butterfly study. Submitted to U.S. Bureau of Land Management, Grand Junction, CO. Austin, G.T. 1998. New species of Nymphalidae (Lepidoptera) from Nevada and Arizona. Pages 573-586 in T.C. Emmel, editor. Systematics of western North American butterflies. Mariposa Press, Gainesville, FL. 878 pp. Baird, V.B. 1942. Wild violets of North America. University of California Press, Berkeley, CA. Bean, D. 2005. Bio-control update. PowerPoint presentation from October 12-14, 2005 Tamarisk Symposium. Available online at: http://www.coopext.colostate.edu/TRA/PLANTS/index.html#http://www.coopext.colostat e.edu/TRA/Tamarisk2005Presentations.html. Boggs, C.L. 1986. Reproductive strategies of female butterflies: variation in and constraints on fecundity. Ecological Entomology 11:7-15. Boggs, C.L. and C.L. Ross. 1993. The effect of adult food limitation on life history traits in (Lepidoptera: Nymphalidae). Ecology 74:433-441. Britten, H.B. and J.W. Glasford. 2002. Genetic population structure of the Dakota skipper (Lepidoptera: Hesperia dacotae): A North American native prairie obligate. Conservation Genetics 3:363-374. Britten, H.B., P.F. Brussard, D.D. Murphy, and G.T. Austin. 1994. Colony isolation and isozyme variability of the western seep fritillary, Speyeria nokomis apacheana (Nymphalidae), in the western Great Basin. Great Basin Naturalist 54(2):97-105. Brittnacher, J.G., S.R. Sims, and F.J. Ayala. 1978. Genetic differentiation between species of the genus Speyeria (Lepidoptera: Nymphalidae). Evolution 32:199-210. Brock, J.P. and K. Kaufman. 2003. Butterflies of North America. Houghton Mifflin, New York, NY. 383 pp. Brown, F.M. 1957. Itineraries of the Wheeler Survey Naturalists 1871 – Ferdinand Bischoff. Journal of the New York Entomological Society 65:219-234. Brown, F.M. 1965. The types of the nymphalid butterflies described by William Henry Edwards: Part 1: Argynninae. Transaction of the American Entomological Society 91:233-350. Brussard, P.F. 1970. Field techniques for investigations of population structure in a “ubiquitous” butterfly. Journal of the Lepidopterists’ Society 25:22-29. Cary, S.J. and R. Holland. 1992. New Mexico butterflies: checklist, distribution, and conservation. Journal of Research on the Lepidoptera 31(1-2):57-82. Colorado Department of Natural Resources. 2004. 10-year strategic plan on the comprehensive removal of tamarisk and the coordinated restoration of Colorado’s native riparian ecosystems. Prepared by the Colorado Department of Natural Resources pursuant to Executive Order # D 002 03. Submitted to Governor Bill Owens January 8, 2004. Available online at: http://www.tamariskcoalition.org/TamariskCoalition//Downloads/Complete_ Tamarisk_10_year_%20plan.pdf. Colorado Natural Heritage Program. 2004. Nokomis fritillary element global rank (EGR) report. Colorado Natural Heritage Program, Fort Collins, CO.

36 37 Colorado Natural Heritage Program. 2005a. Great Basin silverspot butterfly element occurrence records. Colorado Natural Heritage Program, Fort Collins, CO. Received February 2005. Colorado Natural Heritage Program. 2005b. Great Basin silverspot butterfly element state rank (ESR) report. Colorado Natural Heritage Program, Fort Collins, CO. Cox, B. 2005. Wildlife, Fish and Botany Program Manager, USDA Forest Service, Pueblo, CO. Personal communication. Dana, R.P. 1985. Effects of prescribed burning on two prairie-obligate skippers, Hesperia dacotae Skinner and H. ottoe Edwards (Lepidoptera, Hesperiidae). p. 15 in Ninth North American prairie conference abstracts of contributed papers. Moorhead State University, Moorhead, MN. Dana, R.P. 1989. Biologies of the prairie skippers Hesperia dacotae and H. ottoe (Lepidoptera: Hesperiidae), and factors affecting mortality in prescribed burning of their habitat in spring. Ph.D. dissertation, University of Minnesota, St. Paul, MN. 201 pp. Dana, R.P. 1991. Conservation management of the prairie skippers Hesperia dacotae and Hesperia ottoe: basic biology and threat of mortality during prescribed burning in spring. Minnesota Agricultural Experiment Station Bulletin. 594-1991 St. Paul, MN. 63 pp. dos Passos, C.F. 1964. A synonymic list of the Neartic Rhopalocera. Lepidopterists’ Society Memoir 1:1-145. dos Passos, C.F. and L.P. Grey. 1947. Systematic catalogue of Speyeria (Lepidoptera, Nymphalidae) with designations of types and fixations of type localities. American Museum Novitates 1370:1-57. Edwards, W.H. 1874. Notes on the larvae of cybele, aphrodite and diana. Canadian Entomologist 6:121- 125. Edwards, W.H. 1897. The butterflies of North America. Published by author. Philadelphia, Boston, and New York. 3 volumes. Ehrlich, P.R. 1983. Summer butterflies in Dinosaur National Monument. Journal of the Lepidopterists’ Society 37(1): 91-92. Ehrlich, P.R. and S.E. Davidson. 1960. Techniques for capture-recapture studies of Lepidoptera populations. Journal of the Lepidopterists’ Society 14:227-229. Ellis, S. 1989. Preserve design for the Nokomis fritillary butterfly colonies, Unaweep Canyon, Mesa County, Colorado. Unpublished report submitted to the Nature Conservancy, Colorado Field Office, and U.S. Bureau of Land Managment, Grand Junction, CO. Emmel, J.F., O. Shields, and D.E. Breedlove. 1970 (1971). Larval foodplants for North American butterflies. Part 2. Journal of Research on the Lepidoptera 9(4):233-242. Ferris, C.D. 1969. Some additional notes on mating behavior in butterflies. Journal of the Lepidopterists’ Society 23: 271-272. Ferris, C.D. 1974. A note on habitat and geography. Journal of the Lepidopterists’ Society 28:166-167. Ferris, C.D. and F.M. Brown. 1981. Butterflies of the Rocky Mountain States. University of Oklahoma Press, Norman, OK. Ferris, C.D. and M. Fisher. 1971. A revision of Speyeria nokomis (Nymphalidae). Journal of the Lepidopterists’ Society 25(1):44-52. Fleishman, E., C. Ray, P. Sjögren-Gulve, C.L. Boggs, and D.D. Murphy. 2002. Assessing the relative roles of patch quality, area, and isolation in predicting metapopulation dynamics. Conservation Biology 16:706-716. Frankel, O.H. and M.E. Soule. 1981. Conservation and evolution. Cambridge University Press, Cambridge, MA. 327 pp. Fuhlendorf, S.D. and D.M. Engle. 2001. Restoring heterogeneity on rangelands: ecosystem management based on evolutionary grazing patterns. BioScience 51:625-632.

38 39 Grey, L.P. 1989. Sundry Argynnine concepts revisited (Nymphalidae). Journal of the Lepidopterists’ Society 43:1- 10. Hammond, P.C. 1974. An ecological survey of the nymphalid butterfly genus Speyeria. M.S. Thesis, University of Nebraska, Lincoln, NE. Hammond, P.C. and D.V. McCorkle. 1983(84). The decline and extinction of Speyeria populations resulting from human environmental disturbances (Nymphalidae: Argynninae). Journal of Research on the Lepidoptera 22: 217-224. Helzer, C.J. and A.A. Steuter. 2005. Preliminary effects of patch-burn grazing on a high-diversity prairie restoration. Ecological Restoration 23(3):167-171. Hovanitz, W. 1969 (1970). Habitat: Argynnis nokomis. Journal of Research on the Lepidoptera 8(1):20. Huebschman, J.J. and T.B. Bragg. 2000. Response of regal fritillary (Speyeria idalia Drury) to spring burning in an eastern Nebraska tallgrass prairie, USA. Natural Areas Journal 20(4):386-388. IUCN. 2004. 2004 IUCN Red List of Threatened Species. Available online at: www.redlist.org [Accessed on 09 March 2006]. Klots, A.B. 1951. A field guide to the butterflies of North America, east of the Great Plains. Houghton Mifflin Co., Boston, MA. 349 pp. Kopper, B.J., D.C. Margolies, and R.E. Charlton, 2001a. Notes on the behavior of Speyeria idalia (Drury) (Nymphalidae) larvae with implications that they are diurnal foragers. Journal of the Lepidopterists’ Society 54(3):96-97. Kopper, B.J., S. Shu, R.E. Charlton, and S.B. Ramaswamy. 2001b. Evidence for reproductive diapause in the fritillary Speyeria idalia (Lepidoptera: Nymphalidae). Entomological Society of America 94(3):427-432. Levins, R. 1970. Extinction. In: M. Gesternhaber, editor. Some mathematical problems in biology. American Mathematical Society, Providence, RI. Lowry, D. 2005. Forest Wildlife Biologist, Arapaho-Roosevelt National Forests and Pawnee National Grassland, Fort Collins, CO. Personal communication. MacNeill, C.D. 1964. The skippers of the genus Hesperia in western North America, with special reference to California (Lepidoptera: Hesperiidae). University of California Publications in Entomology 35:1-230. Mason, K.R. 2001. Comparison of prairie sites and classification of their habitat attributes in relation to abundance of the regal fritillary butterfly (Speyeria idalia). Final report submitted to the Minnesota Department of Natural Resources. 26 pp. Mattoon, S.O., R.D. Davis, and O.D. Spencer. 1971. Rearing techniques for species of Speyeria (Nymphalidae). Journal of the Lepidopterists’ Society 25(4):247-256. Mikesic, D. 2006. Zoologist, Navajo Natural Heritage Program, Window Rock, AZ. Personal communication. Miller, J.Y. (Ed.). 1992. The common names of North American butterflies. Smithsonian Institution Press, Washington, D.C. 177 pp. Miller, L.D. and F.M. Brown. 1981. A catalogue/checklist of the butterflies of America north of Mexico. Lepidopterists’ Society Memoir 2:1-280. Moffat, M. and N. McPhillips. 1993. Management for butterflies in the northern Great Plains: A literature review and guidebook for land managers. USDI Fish and Wildlife Service, Pierre, SD. 19 pp. Nagel, H.G., T. Nightengale, and N. Dankert. 1991. Regal fritillary butterfly population estimation and natural history on Rowe Sanctuary, Nebraska. Prairie Naturalist 23:145-152. NatureServe. 2006. NatureServe Explorer: An online encyclopedia of life [web application]. Version 4.7. NatureServe, Arlington, VA. Available online at: http://www.natureserve.org/explorer [Accessed on March 1, 2006].

38 39 Navajo Fish and Wildlife Department. 2005. Navajo endangered species list: Resources Committee Resolution No. RCAU-103-05 [Effective August 9, 2005]. Navajo Fish and Wildlife Department, Window Rock, AZ. North American Butterfly Association. 2001. Checklist and English names of North American butterflies. Second edition. Checklist available online at: http://www.naba.org/pubs/enames2.html. Introduction and comments available online at: http://www.naba.org/ftp/check2com.pdf. Norton, A. and E. Lane. 2005. Bio-control in Colorado. PowerPoint presentation from October 12-14, 2005 Tamarisk Symposium. Available online at: http://www.coopext.colostate.edu/TRA/PLANTS/index.html#http://www.coo pext.colostate.edu/TRA/Tamarisk2005Presentations.html. Opler, P.A. 1981. Management of prairie habitats for insect conservation. Natural Areas Journal 1:3-6. Opler, P.A. and G.O. Krizek. 1984. Butterflies east of the Great Plains. Johns Hopkins University Press, Baltimore, MD. 294 pp. Opler, P.A. and A.D. Warren. 2003. Butterflies of North America. 2. Scientific names list for butterfly species of North America, north of Mexico. Available online at: http://www.biology.ualberta.ca/old_site/uasm// Opler&Warren.pdf. Opler, P.A. and A.B Wright. 1999. Peterson field guide to western butterflies. Revised edition. Houghton Mifflin Co., Boston, MA. 540 pp. Opler, P.A., H. Pavulaan, R.E. Stanford, and M. Pogue, coordinators. 2006. Butterflies and moths of North America. Mountain Prairie Information Node, Bozeman, MT. Available online at: http://www.butterfliesandmoths.org. Panzer, R. 1988. Managing prairie remnants for insect conservation. Natural Areas Journal 8:83-90. Panzer, R. 1998. Insect conservation within the severely fragmented eastern tallgrass prairie landscape. PhD dissertation. University of Illinois, Urbana-Champaign, IL. Panzer, R. 2002. Compatibility of prescribed burning with the conservation of insects in small, isolated prairie reserves. Conservation Biology 16:1296-1307. Platt, J.R. 1964. Strong inference. Science 146:347-353. Pollard, E. 1977. A method of assessing changes in the abundance of butterflies. Biological Conservation 12:115- 134. Pollard, E. 1982. Monitoring butterfly abundance in relation to the management of a nature reserve. Biological Conservation 24:317-328. Pollard, E. and T.J. Yates. 1993. Monitoring butterflies for ecology and conservation. The British butterfly monitoring scheme. Institute of Terrestrial Ecology and Joint Nature Conservation Committee. Chapman and Hall, London. 274 pp. Pollard, E., D.O. Elias, M.J. Skelton, and J.A. Thomas. 1975. A method of assessing the abundance of butterflies in Monks Wood National Nature Reserve in 1973. Entomological Gazette 26:79-88. Potter, K.M. 2005. Wildlife Technician, White River National Forest, Glenwood Springs, CO. Personal communication. Pyle, R., M. Bentzien, and P. Opler. 1981. Insect Conservation. Annual Review of Entomology 26:233-258. Royer, R.A. 2002. On the status of five sensitive butterfly species in McKenzie District Pastures 12, 13, and 14, McKenzie County, North Dakota. Dakota Prairie Grasslands, USDA Forest Service. Royer, R.A. 2003. On the status of five sensitive butterfly species in McKenzie District Pasture 7, McKenzie County, North Dakota. Dakota Prairie Grasslands, USDA Forest Service. Royer, R.A., J. Austin, and W. Newton. 1998. Checklist and “Pollard Walk” butterfly survey methods on public lands. American Midland Naturalist 140(2):358-371. Scott, J.A. 1977. Competitive exclusion due to mate searching behavior, male-female emergence lags and fluctuation in number of progeny in model invertebrate populations. The Journal of Animal Ecology 46(3):909-924. 40 41 Scott, J.A. 1981 (1983). An apparent interspecific F1 hybrid Speyeria (Nymphalidae). Journal of Research on the Lepidoptera 20(3):174-175. Scott, J.A. 1986. The butterflies of North America. Stanford University Press, Stanford, CA. 583 pp. Scott, J.A. and S.A. Mattoon. 1981 (1982). Early stages of Speyeria nokomis (Nymphalidae). Journal of Research on the Lepidoptera 20(1):12-15. Shields, O., J.F. Emmel, and D.E. Breedlove. 1969 (1970). Butterfly larval foodplant records and a procedure for reporting foodplants. Journal of Research on the Lepidoptera 8(1):21-36. Sims, S.R. 1984. Reproductive diapause in Speyeria (Lepidoptera: Nymphalidae). Journal of Research on the Lepidoptera 23(3):211-216. Stanford, R.E. and P.A. Opler. 1993. Atlas of western USA butterflies, including adjacent parts of Canada and Mexico. Published by authors. Denver, CO. 275 pp. Swengel, A.B. 1996. Effects of fire and hay management on abundance of prairie butterflies. Biological Conservation 76:73-85. Swengel, A.B. 1998. Effects of management on butterfly abundance in tallgrass prairie and pine barrens. Biological Conservation 83(1):77-89. Swengel, A.B. 2001. A literature review of insect responses to fire, compared to other conservation managements of open habitat. Biodiversity and Conservation 10(7):1141-1169. Swengel, A.B. 2004. Good news for regal fritillaries. Wisconsin Entomological Society Newsletter 31(2):3-4. Swengel, A.B. and S.R. Swengel. 1999. Observations of prairie skippers (Oarisma poweshiek, Hesperia dacotae, H. ottoe, H. leonardus pawnee, and Atrytone arogos iowa) (Lepidoptera: Hesperiidae) in Iowa, Minnesota, and North Dakota during 1988-1997. Great Lakes Entomologist 32(4):267-292. Swengel, A.B. and S.R. Swengel. 2001. A ten-year study of the status and trend of the regal fritillary (Speyeria idalia) (Lepidoptera: Nymphalidae) in Wisconsin. Great Lakes Entomologist 34(1):111-128. Swisher, W.L. and A.L. Morrison. 1969. New of the Lepidopterists’ Society 15 April:4. Tilden, J.W. and A.C. Smith. 1986. A field guide to western butterflies. Houghton-Mifflin Co., Boston, MA. 370 pp. 23 color plates. USDA Forest Service. 2001. Forest Service Region 2 sensitive species evaluation form for Nokomis fritillary (Speyeria nokomis nokomis). 25 August 2001 evaluation by Paul A. Opler. Avaulable online at: http://www.fs.fed.us/r2/ projects/scp/evalrationale/evaluations/insects/nokomisfritillary.pdf. USDA Forest Service. 2003. Forest Service Region 2 sensitive species recommendation rationale for Nokomis fritillary (Speyeria nokomis nokomis). 13 January 2003 revision by Gary Patton. Available online at: http: //www.fs.fed.us/r2/projects/scp/evalrationale/rationales/insects/nokomisfritillary.pdf. USDA Forest Service. 2004. Forest Service sensitive species that are not listed or proposed under the ESA. Unpublished Report. December 1, 2004. Available online at: http://www.fs.fed.us/biology/resources/pubs/tes/ fs_ss_1dec04.pdf [Accessed on October 2005]. USDA Natural Resources Conservation Service. 2005. The PLANTS Database. Data compiled from various sources by Mark W. Skinner. National Plant Data Center, Baton Rouge, LA 70874-4490. Available online at: http: //plants.usda.gov. Version 3.5. U.S. Department of the Interior, Bureau of Land Management. 1985. Research Natural Area Designation – Unaweep Seep. Notice of designation. Federal Register 48:23716. U.S. Fish and Wildlife Service. 1984. 50 CFR Part 17, Endangered and threatened wildlife and plants; review of invertebrate wildlife for listing as endangered or threatened species. Notice of review. Federal Register 49: 21664.

40 41 U.S. Fish and Wildlife Service. 1989. 50 CFR Part 17, Endangered and threatened wildlife and plants; animal notice of review. Notice of review. Federal Register 54:554. U.S. Fish and Wildlife Service. 1991. 50 CFR Part 17, Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species. Notice of review. Federal Register 56(225):58804. U.S. Fish and Wildlife Service. 1994. 50 CFR Part 17, Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species. Notice of review. Federal Register 59(219):58982. U.S. Fish and Wildlife Service. 1996. 50 CFR Part 17, Endangered and threatened wildlife and plants; review of plant and animal taxa that are candidates for listing as endangered or threatened species. Notice of review. Federal Register 61(40):7596. U.S. Fish and Wildlife Service. 2001. Oregon silverspot butterfly Speyeria( zerene hippolyta) revised recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. 113 pp. Wagner, D.L. 1995. Rearing regals for reintroduction: playing the odds but still losing ground. American Butterflies 3(2):19-23. Wagner, D.L., M.S. Wallace, G.H. Boettner, and J.S. Elkinton. 1997. Status update and life history studies on the regal fritillary (Lepidoptera: Nymphalidae). Pages 261-275 in P.D. Vickery and P.W. Dunwiddie, editors. Grasslands The U.S. Department of Agriculture (USDA) prohibits of northeastern North America: ecology and conservation of native and agricultural landscapes. discrimination in all its programs and activities on Audubon, Lincoln, MA. the basis of race, color, national origin, age, disability, Williams, B.L. 2006. Assistant Professor, Departments of Zoology and Microbiology & Molecular Genetics, Michigan and where applicable, sex, marital status, familial State University, East Lansing, MI. Personal communication. status, parental status, religion, sexual orientation, Williams, B.L., J.D. Brawn, and K.N. Paige. 2003. Landscape scale genetic effects of habitat fragmentation on a high genetic information, political beliefs, reprisal, or gene flow species:Speyeria idalia (Nymphalidae). Molecular Ecology 12:11-20. because all or part of an individual’s income is Zercher, D., P. McElhenny, and P. Mooreside. 2002. Habitat management plan for the regal fritillary (Speyeria idalia) derived from any public assistance program. (Not at the Fort Indiantown Gap National Guard Training Center, Annville, Pennsylvania. 5-year implementation all prohibited bases apply to all programs.) Persons period: 2002-2006. Final plan prepared for the Pennsylvania Department of Military and Veterans Affairs, Fort with disabilities who require alternative means for Indiantown Gap, Environmental Section, Annville, PA. communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, DC 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.

42 The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, DC 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.

42