The Kleinfelder Blog

Cas Carroll

Cas Carroll, a biologist in our Denver, CO office, is the lead author of a recently published article in Endangered Species Research — an Inter-Research Science Publisher journal — titled “While they’re still here: assessing status and habitat for the last populations of the Carson wandering skipper Pseudocopaeodes eunus obscurus.”

The article and Cas’ work explores the ecology, distribution, and habitat requirements of grass skippers of conservation concern, including the federally endangered Carson wandering skipper (Pseudocopaeodes eunus obscurus), which is a small tawny orange butterfly found in grassland habitats on alkaline substrates in Washoe County, Nevada and Lassen County, California (U.S. Fish & Wildlife).

Across the world, grassland declines over the last century have coincided with the declines of many grass-feeding butterflies, and the Carson wandering skipper (CWS) is one such taxon. The CWS is a federally endangered subspecies of grass skipper butterfly with only three remaining populations on the western edge of the Great Basin Desert in Nevada and California. Since its federal listing under the Endangered Species Act in 2001, it has been monitored annually but has not been the subject of intensive research.

To improve understanding of the CWS, count data from surveys over the last several decades was used to assess CWS population status, and vegetation data from 2021-22 in areas that are currently occupied by the subspecies — and in areas that have no record of CWS occupancy but otherwise met some or all criteria for suitable habitat — was collected.

Findings indicated that the CWS is in decline and its habitat is characterized by low to moderate densities of saltgrass (Distichlis spicata), the larval host, and the presence of alkaline- or salt-associated nectar resources as well as other saltgrass community associates.

The article discusses the possibility that the remaining occupied habitat is not necessarily optimal habitat, as well as the implications of status assessments of the CWS for other butterfly taxa with severely restricted ranges in the arid western United States.

Cas is a Ph.D. candidate at the University of Nevada, Reno, studying CWS and other skipper species. Cas also supports Kleinfelder’s Environmental Planning & Permitting team as a flex employee.

You can access the full article for free by clicking “Full text in PDF format” beneath the abstract here.