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Abstract 1. The Poweshiek skipperling [Oarisma poweshiek(Parker, 1870; Lepidoptera: Hesperiidae)] is a federally endangered butterfly that was historically common in prairies of the upper Midwestern United States and Southern Manitoba, Canada. Rapid declines over the last 20 years have reduced the population numbers to four verified extant sites. The causes of Poweshiek skipperling decline are unknown. 2. We aggregated all known Poweshiek skipperling occurrence records to examine the spatiotemporal patterns of Poweshiek skipperling decline. Ecological niche models were developed for five time frames (1985, 1990, 1995, 2000 and 2005) and three spatial extents (eastern occupied range, western occupied range and total occupied range). We used a backward elimination method to investigate the effects of climate and land use on the ecological niche of Poweshiek skipperling. 3. Predictors of occurrence changed over time and across the geographical extent of Poweshiek skipperling. Land use covariates were retained in east models. In the west and total extent, climate variables contributed the most to model predictive power for the 1985, 1990 and 1995 models; land use variables contributed the most to model predictive power in the 2000 and 2005 models. 4. During the rapid decline in Poweshiek skipperling population numbers occurring at the turn of the century, probability of Poweshiek skipperling presence was being driven by proportion of natural land cover and distance to nearest grassland/wetland. Our results suggest that these land use variables are important landscape‐level variables to consider when developing risk assessments of extant populations and potential reintroduction sites.
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This content will become publicly available on April 4, 2026
While they’re still here: assessing status and habitat for the last populations of the Carson wandering skipper Pseudocopaeodes eunus obscurus
Across the world, grassland declines over the last century have coincided with the declines of many grass-feeding butterflies, and the Carson wandering skipperPseudocopaeodes eunus obscurus(CWS) is one such taxon. The CWS is a federally endangered subspecies of grass skipper butterfly with only 3 remaining populations on the western edge of the Great Basin Desert, in Nevada and California, USA. 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 our understanding of the CWS, we used count data from surveys over the last several decades to assess CWS population status. In addition, to better understand and characterize current habitat for the CWS, we collected vegetation data from 2021-2022 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. We found that the CWS is in decline and that its habitat is characterized by low to moderate densities of saltgrassDistichlis spicata, the larval host, and the presence of alkaline- or salt-associated nectar resources as well as other saltgrass community associates. We discuss the possibility that the remaining occupied habitat is not necessarily optimal habitat. We also discuss the implications of our status assessment of the CWS for other butterfly taxa with severely restricted ranges in the arid western USA.
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- Award ID(s):
- 2114793
- PAR ID:
- 10587426
- Publisher / Repository:
- Inter-Research
- Date Published:
- Journal Name:
- Endangered Species Research
- Volume:
- 56
- ISSN:
- 1863-5407
- Page Range / eLocation ID:
- 173 to 186
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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