San Diego Management & Monitoring Program


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2021 San Diego Insect Conservation Update: Hermes Copper, Harbison's Dun Skipper, Pollinators powerpoint presentation

Lead author: Dan Marschalek
Presentation from the August 25, 2021 SDMMP Management and Monitoring Coordination Meeting.

2020 Hermes copper & Harbison's dun skipper" Where we are and where we are going? powerpoint presentation

Lead author: Dan Marschalek
Presentation at the August 26, 2020 SDMMP Management and Monitoring Coordination Meeting.

2020 Recording - August 2020 SDMMP Management and Monitoring Coordination Meeting recording

Lead author: Dan Marschalek
Recording for the August 26, 2020 SDMMP Mgmt. and Mon. Coordination Meeting. Dan Marschalek (University of Central Missouri) - "Hermes copper & Harbison's dun skipper: Where we are and where we are going?" Spring Strahm (Conservation Biology Institute) – “Status update on Laguna Mountains Skipper reintroduction effort” and “Augmenting Quino checkerspot butterfly in the San Diego National Wildlife Refuge”

2021 Recording - August 2021 SDMMP Management and Monitoring Coordination Meeting recording

Lead author: Dan Marschalek
Recording for the August 25, 2021 SDMMP Mgmt. and Mon. Coordination Meeting with Dan Marschalek (UCM) and Bruce Markman (UCD).

2015 Initial Investigation of Critical Biological Uncertainties for Harbison's dun skipper (Euphyes vestris harbisoni) on Conserved Lands in San Diego County report

Lead author: Douglas Deutschman
The Harbison's dun skipper (Euphyes vestris harbisoni) is a rare subspecies with a restricted distribution, known only from San Diego County and southern Orange County. Larvae are host-specialists, feeding only on the San Diego sedge (Carex spissa) that is often associated with riparian oak woodlands. Entomologists have expressed concern that the Harbison's dun skipper may be threatened due to habitat loss and degradation. The skipper was once considered a Category 2 species by the United States Fish and Wildlife Service and petitioned to be listed under the federal Endangered Species Act. Currently, it is a covered species in some HCP/NCCP plans in San Diego County. Little is known about this skipper, as the few papers written are limited to describing the general life history and providing a vague distribution. This project is the first phase of a planned comprehensive monitoring program for the Harbison's dun skipper, designed to assist in the development of effective management and conservation practices. We focused on describing the distribution of the skipper, estimating population status and trend, describing habitat requirements of the larvae and adults, and identifying potential threats to the long-term persistence of the species as well as recommendations for monitoring and management. Using herbarium records, information from biologists, and historical Harbison's dun skipper locations, we were able to find San Diego sedge at 38 general locations, primarily on conserved lands. All sedge plants were found in or immediately adjacent to a riparian oak woodland except two small patches. However, both of these locations also had oak woodlands with San Diego sedge present. In many cases, oak woodlands were patchily distributed along a creek and the sedge was only found in those woodlands. We did not find San Diego sedge in or along pools of still/standing water, only in areas with moving water or a dry ravine. We were able to identify 26 historic Harbison's dun skipper localities from museum specimens, peer-reviewed literature, technical reports, and notes from local biologists. Most often, these locality data provided a general description rather than a specific point. Therefore, it can be difficult to know if we were revisiting the same location. Of the 34 locations with San Diego sedge that we surveyed for the skipper, 18 (53%) were occupied which is well below the occupancy rate described by Brown (1982). [consult report for rest of Exec. Summary]

2016 Rare Butterfly Management and Conservation Planning, Task 7: 2016 Harbison's Dun Skipper Flight Season Surveys report

Lead author: Dan Marschalek
Surveys for Harbison’s dun skipper adults were conducted to assess year to year variation in population size. Field visits were used to document use including plants used for nectar sources, as well as obtain non-lethal genetic samples. A rapid habitat assessment was conducted at each site which included general woodland tree species composition, condition of San Diego sedge plants, and recording potential threats to the Harbison’s dun skipper. We were not able to detect Harbison’s dun skipper adults at all sites, including the canyon south of San Pasqual Academy where it appears the skipper has been extirpated due to wildlife and drought. At four sites (Barrett Lake, Lake Hodges, Skye Valley Road, Sycuan Peak Ecological Reserve), the peak daily number was near or exceeded 10 individuals. At the other sites, no more than four individuals were seen on a single day. There was not a clear relationship between the 2014 and 2016 counts as some were higher, some lower, and some quite similar. In 2016, we observed adults nectaring on sacapellote (Acourtia microcephala) and California rose (Rosa californica), two plant species not previously recorded. The current list of known nectar sources includes 20 species, nearly all of which have white, purple, or pink flowers. Habitat assessments occurred at 23 locations with recent Harbison’s dun skipper observations. These surveys occurred just after the flight season (27 July – 9 August 2016). Oak species dominated the woodlands, with some sycamore and willow trees. The condition of the San Diego sedge plants ranged from nearly all very healthy (green) to all dead. Most of the plants had green leaves with brown tips, suggesting some water stress although this may be typical during the late summer and early fall. The most common threat to the Harbison’s dun skipper was the presence of the goldspotted oak borer (Agrilus auroguttatus). In addition, more than 15 non-native plant species were detected in the riparian areas.

2021 Hermes Copper Butterfly Surveys and Translocation Efforts - Task 8: 2021 Harbison’s Dun Skipper Adult Surveys report

Lead author: Dan Marschalek
This report summarizes our survey efforts of 2021. Additional efforts for this project/task are planned for 2022 and will include a marking study to calibrate transect counts with population size estimates, and quantify habitat preferences. In 2021, surveys for Harbison’s dun skipper adults were conducted to assess year to year variation in population size and update the status of each local population/site. Surveys focused on the relatively small geographic area where skippers were observed in past years. In 2013- 2017, 14 sites had confirmed observations of Harbison’s dun skipper adults. All but one of these sites were surveyed in 2021, with Harbison’s dun skipper adults observed at only six sites. Population sizes at those six sites were similar to the smallest population sizes recorded during the 2013-2017 surveys. Overall, transect counts (visual observations) continue to describe small populations when skippers are present. However, the large size and uneven terrain of some riparian oak woodlands, patchy distribution of adult skippers, and shifting locations of San Diego sedge present challenges to accurately categorizing presence/absence and relative population sizes. (SANDAG TransNet EMP Contract #5005783)

2018 San Diego County Harbison’s Dun Skipper (Euphyes vestris harbisoni) Habitat Conservation and Management Plan report

Lead author: Dan Marschalek
This plan provides a summary of what is known regarding the Harbison’s dun skipper, including life history, historic and current distribution, movement patterns, suitable habitat, and threats. A thorough understanding of the species is necessary to make appropriate adaptive management recommendations in an attempt to alleviate the current threats to the species. To develop this plan, we: 1. Reviewed existing data, including historic Harbison’s dun skipper locations, recent (2013-2017) survey data, property ownership to identify conserved lands for potential surveys, management, and acquisitions, and 2. Consulted with the wildlife agencies and other stakeholders to ensure that the most current information regarding Harbison’s dun skipper biology, management, regulations, conserved lands, and potential acquisitions were included.