Assessing the status of the threatened skipper, Euphyes vestris harbisoni, in southern California

Euphyes vestris is found throughout much of the United States; however, one of the skipper’s subspecies (Euphyes vestris harbisoni) is geographically isolated from the other subspecies. Euphyes v. harbisoni inhabits riparian oak woodlands in southern California and northern Mexico and is only known to feed on Carex spissa as a larva. Due to concerns about the long-term persistence of Euphyes v. harbisoni, the United States Fish and Wildlife Service previously listed the skipper as a Category 2 species, suggesting that an endangered or threatened status may be appropriate but that a formal decision required more data. In recent years, skipper numbers have declined due to loss of habitat and other ecological factors such as wildfire and drought. We conducted field surveys at locations of past populations during the 2021 flight season to update the status and trends of local populations, assess threats, and evaluate habitat conditions.