Hesperia leonardus montana
(Skinner, 1911)
Pawnee Montane Skipper
T1T1Global Rank
Not evaluatedIUCN
HighThreat Impact
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.121210
Element CodeIILEP65061
Record TypeSPECIES
ClassificationSubspecies
Classification StatusStandard
Name CategoryInvertebrate Animal
IUCNNot evaluated
Endemicendemic to a single state or province
KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderLepidoptera
FamilyHesperiidae
GenusHesperia
Concept Reference
Pelham, J. P. 2008. A catalogue of the butterflies of the United States and Canada with a complete bibliography of the descriptive and systematic literature. The Journal of Research on the Lepidoptera. Volume 40. 658 pp. Revised 14 February, 2012.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2021-03-23
Change Date1998-09-01
Edition Date2021-03-23
Edition AuthorsSchweitzer, D.F. (2009), Sovell, J. and N. Sears (2021)
Threat ImpactHigh
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences1 - 5
Rank Reasons
This subspecies has a very limited range in a single drainage system with possible large-scale elimination or alteration of habitat. Climate change, which has the potential to result in increased periods of drought and intensity and frequency of wildfires, poses a serious threat to this skipper. Because of the risk associated with ongoing threats, it is classified as threatened by the Endangered Species Act.
Range Extent Comments
The range of this subspecies is restricted to four Colorado counties (Teller, Park, Jefferson, and Douglas) within an area approximately 23 miles long and 5 miles wide (or 115 square miles) along the South Platte River drainage system. The total area of skipper habitat is 24,830 acres (about 38.7 square miles), of which 70 percent occurs on the Pike and San Isabel National Forests (USFWS 2020).
The range can be divided into three subpopulations (USFWS 1998): 1) Mainstem South Platte subpopulation (12,787 acres), which includes the mainstem of South Platte River from the North Fork/South Fork confluence up to Deckers, including Horse Creek; 2) Cheesman Reservoir subpopulation (5,758 acres); and 3) North Fork subpopulation (6,285 acres) (USFWS 2020).
The range can be divided into three subpopulations (USFWS 1998): 1) Mainstem South Platte subpopulation (12,787 acres), which includes the mainstem of South Platte River from the North Fork/South Fork confluence up to Deckers, including Horse Creek; 2) Cheesman Reservoir subpopulation (5,758 acres); and 3) North Fork subpopulation (6,285 acres) (USFWS 2020).
Occurrences Comments
There are a few large occurrences in the South Platte River Canyon drainage. The skipper occupies only about 38 square miles of patchy habitat with interchange of individuals among the patches.
Threat Impact Comments
The primary threats to the Pawnee montane skipper are increasing temperature, fire, and drought associated with climate change (Sovell 2021). It is likely that the Pawnee montane skipper is adapted to both short- and longer-term droughts, but at small population sizes, like those exhibited by this threatened butterfly, stochastic abiotic factors such as fire and drought, can severely compromise population persistence and may lead to extinction (Sovell and Drummond 2006). The Two Forks Dam and Reservoir construction was not approved by the EPA in 1990, but plans to develop a reservoir in the drainage may resurface in the near term. Activities with major and moderate effects include direct and indirect habitat elimination and displacement through development for housing, recreation, agriculture, forestry and related activities (USFWS 1998, Opler 1987). Invasion of knapweed and other noxious exotic plants has been documented in both Jefferson and Douglas counties. Fire suppression and interruption of other ecosystem processes may create large blocks of unsuitable habitat over the long term. Additionally, fire suppression may lead to a future large-scale fire occurrence. Outbreaks of the Douglas-fir tussock moth (perhaps facilitated by the denser tree growth) may increase the chances of insecticide application within the skipper habitat. In June of 1996, a human-induced, accidental forest fire burned a portion of the habitat at its type locality, Buffalo Creek. Fire was hot and severe, and subsequently, the population there was destroyed. The Hayman and Schoonover fires of 2002 burned 40% of the skipper habitat, much of that at high severity.
Ecology & Habitat
Habitat
The skippers occur in dry, open, ponderosa pine woodlands at an elevational range of 6000-7600 feet. The slopes are moderately steep with immature soils derived from Pikes Peak granite. The understory is very sparse in the pine woodlands. Skippers are very uncommon in pine woodlands with a tall shrub understory or where young conifers dominate the understory (USFWS 1994). Based on extensive occurrence data, the following are general characteristics of H.l.montana habitat. A tree canopy cover of 30%, 25% Ponderosa pine crown cover and 5% Douglas fir crown cover. Tree density is less than 120 trees/acre in the smallest size class (0 to 5 dbh), overall tree density is less than 200 trees/acre. Shrub and grass cover is typically less than 10%. Liatris punctata (Prairie gay feather) flowering stem density ranges from 50 to 500/acre and Bouteloua gracilis (Blue grama) cover is 5% or less, but widely available. H. l. montana occurrence and abundance seem to be positively related to Liatris abundance (ERT 1986 1, Sovell 2018). The vegetative community preferred by the skipper is a northern-most extension of the Pinus ponderosa/Bouteloua gracilis (Ponderosa pine/Blue grama grass) habitat type documented from southern Colorado and Northern New Mexico. However, the preferred nectar plant of the skipper, prairie gayfeather, does not occur in similar habitats to the south. The northeastern limit of the Ponderosa pine/Blue grama grass community overlapping with the southwestern limit of the Prairie gayfeather may contribute to the maintenance of the species in this limited area (U.S.F.W.S. 1994). Sloping to gently undulated, mostly steep and sunny. Soil type: decomposing igneous rocks (i.e., red Pikes Peak granite). Open space with good light and air circulation, key vegetation is mixture of thin stands of pine, some woody low shrubs, yucca and host plants. The Pawnee Montane Skipper is found in sparsely wooded grasslands and open pine forests along the Front Range. The are associated with Liatris punctata, Dotted Greyfeather, which flowerslate summer through early fall and Bouteloua gracilis blue grama. The butterfly is known to occur along a 12-mile stretch of canyon bottom along the South Platte River (Ryke et al. 1994)
Terrestrial Habitats
Woodland - ConiferSavanna
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|---|---|
| Colorado | S1 | Yes |
Threat Assessments
| Threat | Scope | Severity | Timing |
|---|---|---|---|
| 6 - Human intrusions & disturbance | Small (1-10%) | Unknown | High (continuing) |
| 6.1 - Recreational activities | Small (1-10%) | Unknown | High (continuing) |
| 7 - Natural system modifications | Large (31-70%) | Serious or 31-70% pop. decline | Moderate (short-term) |
| 7.1 - Fire & fire suppression | Large (31-70%) | Serious or 31-70% pop. decline | Moderate (short-term) |
| 7.2 - Dams & water management/use | Unknown | Extreme or 71-100% pop. decline | Low (long-term) |
| 11 - Climate change & severe weather | Pervasive (71-100%) | Unknown | Unknown |
| 11.2 - Droughts | Pervasive (71-100%) | Unknown | Unknown |
Roadless Areas (1)
South Dakota (1)
| Area | Forest | Acres |
|---|---|---|
| Indian Creek | Buffalo Gap National Grassland | 24,666 |
References (12)
- Opler, P. A., and A. D. Warren. 2002. Butterflies of North America. 2. Scientific Names List for Butterfly Species of North America, north of Mexico. C.P. Gillette Museum of Arthropod Diversity, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado. 79 pp.
- Pelham, J. P. 2008. A catalogue of the butterflies of the United States and Canada with a complete bibliography of the descriptive and systematic literature. The Journal of Research on the Lepidoptera. Volume 40. 658 pp. Revised 14 February, 2012.
- Pelham, J.P. 2023. A catalogue of the butterflies of the United States and Canada. Revised 15 February 2023. http://butterfliesofamerica.com/US-Can-Cat.htm
- Ryke, N., D. Winters, L. McMartin, and S. Vest. 1994. Threatened, Endangered and Sensitive Species of the Pike and San Isabel National Forests and Comanche and Cimarron National Grasslands. May 25, 1994.
- Scott, J. A. 1986. The Butterflies of North America: A Natural History and Field Guide. Stanford University Press, Stanford CA. 583 pp.
- Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). 2005. Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation. online. available: www.xerces.org
- Sovell, J. R. 2014. Pawnee Montane Skipper Vegetation Study for the Upper South Platte Watershed Protection and Restoration Project September 2012. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.
- Sovell, J. R. 2017. Pawnee Montane Skipper Post-fire Habitat Assessment August/September 2016. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado. 62 pp.
- Sovell, J. R. 2019. Pawnee Montane Skipper Post-fire Habitat Assessment: August/September 2018. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.
- Sovell, J. R. 2021. Pawnee Montane Skipper Monitoring Study for the Upper South Platte Watershed Protection and Restoration Project: August 2020. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado. 46 pp.
- U.S. Fish and Wildlife Service (USFWS). 1987. Endangered and threatened wildlife and plants; final rule to determine Pawnee montane skipper (<i>Hesperia leonardus montana</i>) to be threatened species. Fed. Reg., Dept. of the Interior. 52(186):36176-3618
- U.S. Fish and Wildlife Service (USFWS). 1998. Pawnee montane skipper butterfly (<i>Hesperia leonardus montana</i>) recovery plan. Denver, Colorado. 16 pp.