The Pawnee montane skipper is a species with a narrow distribution that is endemic to Colorado. Fire suppression, development of dams and reservoirs andare all threats to the persistence and recovery of this federally threatened species, as noted in the 2020 amendment to the recovery plan.
The skippers occur in dry, open ponderosa pine (Pinus ponderosa) woodlands at an elevational range of 6,000 to 7,500 feet. The slopes are moderately steep with soils derived from Pikes Peak granite as described in the recovery plan from 1998. The understory is limited in the pine woodlands. Blue grama grass (Bouteloua gracilis) and prairie gayfeather (Liatris punctata) are two necessary components of the ground cover strata. Blue grama grass is the primary plant for egg deposition, larvae feeding, larvae overwintering and pupation. The prairie gayfeather is the primary nectar plant for adult skippers, as noted in the 5-year review in 2011. The 1998 recovery plan notes that small clumps of blue grama occur throughout the warm, open slopes inhabited by skippers and that prairie gayfeather occurs throughout the ponderosa pine woodlands. Skippers are very uncommon in pine woodlands with a tall shrub understory or where young conifers dominate the understory.
The optimum skipper conditions are a tree canopy cover of 25% from ponderosa pine and 5% from Douglas fir (Pseudotsuga menziesii), as noted in the 5-year review in 2011. In a 1986 status report that was produced by ERT Company, other general characteristics of Pawnee montane skipper habitat include:
- Tree density of less than 120 trees per acre in a size class of 0 to 5 feet (0 to 152 centimeters) diameter at breast height and overall tree density of less than 200 per acre (per 0.4 hectare)
- Shrub and grass cover generally less than 10%
- Prairie gayfeather flower stem density ranging from 50 to 500 per acre (per 0.4 hectare)
- Blue grama cover 5% or less, but present across the landscape
The skipper’s narrow range is inherently restricted by the area of overlap between the northern extension of the ponderosa pine/blue grama grass community and the southern extension of the prairie gayfeather, as noted in the recovery plan. The total area of skipper habitat is approximately 25,044 acres, of which 13,826 acres occur on the Pike National Forest as noted in the recovery plan.
A dense growth of trees and underbrush covering a large tract.
The skipper has two main plants upon which it feeds, blue grama grass (Bouteloua gracilis), used by larvae, and prairie gayfeather (Liatris punctata), from which adults get their nectar (Liatris pycnostachya), noted in the 5-year review in 2011. Other plants noted as occasional nectar sources include smooth asters (Aster laevis), in upland areas and along gully bottoms where soil moisture is greater, and musk thistle (Carduus nutans), which is especially important along river bottom edges and up some ravines, as noted in the recovery plan. Females of this skipper species were observed along the South Platte River in large numbers on musk thistle, as documented by Opler in 1986. The Colorado Department of Agriculture includes musk thistle among its List B species of noxious weeds, which means that it is a species for which the Commissioner of Agriculture develops and implements state noxious weed management plans, in consultation with the state noxious weed advisory committee, local governments and other interested parties, to stop their continued spread. Other plants occasionally used by Pawnee montane skippers include Canada thistle (Cirsium arvense), bee balm (Monarda spp.), pineywoods geranium (Geranium caespitosum), sunflower (Helianthus spp.), Senecio (Senecio spp.), as documented in the 5-year review. J.R. Sovell documented in 2018 that false goldenaster (Heterotheca villosa) is particularly important when prairie gayfeather is sparse or absent.
The Pawnee montane skipper is a small butterfly with a wingspan slightly more than 1 inch (2.54 centimeters).
The Pawnee montane skipper is a small, brownish-yellow butterfly with a wing span slightly more than 1 inch (2.54 centimeters). Small, dull brownish-yellow, usually distinct spots occur near the outer margins of the upper surface of the wings, while one to four distinct brownish to off-white spots occur on the lower surface of the wings. The ventral spots are larger on the hind wing and are generally whiter on the female butterfly.
Pawnee montane skippers emerge from their pupae as adult butterflies in late July. Usually, males emerge before females by an average of seven to 10 days. Adult emergence and flight period coincides with the flowering period for prairie gayfeather, as documented by ERT Company in 1986, with the primary flight period occurring from late August to early September, as documented by the amendment to the recovery plan in 2020. The species overwinters as young larvae; little is known about the larval and pupal stages, as noted in the 1998 recovery plan. Pupation is generally short, 13 to 23 days, in most butterfly species. The skipper completes its life cycle - egg to larva to pupa to adult butterfly to egg - annually, as L.D. Keenan and others documented in 1986.
Adult females deposit eggs singly and directly on leaves of blue grama grass, the larval food plant, as documented by J.A. Scott and R.E. Stanford in 1982, as well as W.D. McGuire in 1982, and later by P.A. Opler in 1986.
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