Type: report

Article abstract: The Hermes copper (Lycaena hermes) is a rare butterfly endemic to San Diego County and northern Baja California. This species is threatened by recent urbanization and wildfires throughout its range in the United States. Since most individuals and larger populations are found in the southern portion of San Diego County, one large fire could nearly extirpate the species. Wildfires in 2003 and 2007 have already caused extirpations in this region and few recolonizations have been observed. Past efforts have contributed to our understanding of the distribution of the Hermes copper so it is fairly well understood. However, there may still be unknown populations. Surveys associated with the SDG&E Sunrise Powerlink Project discovered several populations by searching linear transects through Cleveland National Forest without specifically targeting Hermes copper. Based on these results, we thought that additional surveys through potential habitat could yield detections of unknown populations. The objective of this project was to search for these populations by conducting surveys in areas not previously searched. Surveys were also conducted in the Elfin Forest area, near previously occupied areas, and three sites that experiences wildfires since 2003 to assess recolonization. During the 2018 flight season, we conducted surveys for Hermes copper adults at 35 sites (transects) determined in consultation with USFWS and USFS biologists. These sites were selected based on habitat, proximity to known populations, and considered previous survey efforts and results. The 2018 Hermes copper flight season started the last couple days of May and extended through the first three weeks of June. This flight season started later than in recent years. Hermes copper adults were detected along only three transects, including at least 55 different adults on the CNF07 transect, 8 on CNF08, and 1 along the maintained Boulder Creek Road. There were no observations at the other transects. Most sites were experiencing very dry conditions, represented by suppressed butterfly numbers, regardless of species, and water stressed plants. (Contract: #5004388, Task Order #4)