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In a rapidly changing world, where species conservation needs vary by local habitat, concentrated conservation efforts at small spatial scales can be critical. Bats provide an array of value to the ecosystems they inhabit; many bat species are also of conservation concern. San Diego County, California, contains 22 of the 41 bat species that occur in the United States, 16 of which are on conservation watchlists. Thus, management of bat communities in San Diego County is a pressing need. Because bats exploit vast areas of the landscape and historical sampling strategies have shifted over time, a standardized way of prioritizing areas of the landscape for management would provide an integral asset to bat conservation. We leveraged long-term bat community survey data from sampling areas across San Diego County to prioritize areas with the most management need. We calculated two types of scores: species scores and threat scores. Species scores incorporated richness and conservation status, and threat scores included landscape level threats that bats could encounter. We found that urbanization, the presence of artificial lights, and areas sampled on unconserved land were all significantly associated with decreases in species richness. Further, using species and threat scores, each sampling area was placed into one of four conservation categories, in order from greatest to least conservation need, ranging from highest priority (high species score, high threat score) to lowest (low species score, low threat score). Additionally, we focused on sampling areas in which Townsend’s big-eared bat (Corynorhinus townsendii) and/or pallid bat (Antrozous pallidus) occurred. These two species are of exceptional conservation concern in San Diego County and across the western United States. We identified urbanization, the presence of artificial lights, and areas sampled on unconserved land as threats that were all significantly associated with the absence of Townsend’s big-eared bat, but not pallid bat. The strategy, methodology, and solutions proposed in our study should assist bat conservation and management efforts wherever bats occur, and can be extended to other species that require conservation attention.

In a rapidly changing world, where species conservation needs vary by local habitat, concentrated conservation efforts at small spatial scales can be critical. Bats provide an array of value to the ecosystems they inhabit; many bat species are also of conservation concern. San Diego County, California, contains 22 of the 41 bat species that occur in the United States, 16 of which are on conservation watchlists. Thus, management of bat communities in San Diego County is a pressing need. Because bats exploit vast areas of the landscape and historical sampling strategies have shifted over time, a standardized way of prioritizing areas of the landscape for management would provide an integral asset to bat conservation. We leveraged long-term bat community survey data from sampling areas across San Diego County to prioritize areas with the most management need. We calculated two types of scores: species scores and threat scores. Species scores incorporated richness and conservation status, and threat scores included landscape level threats that bats could encounter. We found that urbanization, the presence of artificial lights, and areas sampled on unconserved land were all significantly associated with decreases in species richness. Further, using species and threat scores, each sampling area was placed into one of four conservation categories, in order from greatest to least conservation need, ranging from highest priority (high species score, high threat score) to lowest (low species score, low threat score). Additionally, we focused on sampling areas in which Townsend’s big-eared bat (Corynorhinus townsendii) and/or pallid bat (Antrozous pallidus) occurred. These two species are of exceptional conservation concern in San Diego County and across the western United States. We identified urbanization, the presence of artificial lights, and areas sampled on unconserved land as threats that were all significantly associated with the absence of Townsend’s big-eared bat, but not pallid bat. The strategy, methodology, and solutions proposed in our study should assist bat conservation and management efforts wherever bats occur, and can be extended to other species that require conservation attention.

Presentation for the May 25, 2022 SDMMP Management and Monitoring Coordination Meeting.

Recording from the May 25, 2022 SDMMP Management and Monitoring Coordination Meeting. Presentations from Brian Myers (California Polytechnic State University, Pomona) and Amy Vandergast (USGS) - "Integrating 20 years of site-specific bat surveys to help inform a regional bat management plan"; and Robert Fisher (USGS) - "Bat virome study and ties to emerging infectious diseases".

The Living Coast Discovery Center, in partnership with the U.S. Fish and Wildlife Service, Cabrillo National Monument, and the San Diego Natural History Museum conducted surveys to determine bat species composition on and around the Sweetwater Marsh Unit of the San Diego Bay National Wildlife Refuge. Strong historical research suggested that the pallid bat was likely utilizing Sweetwater Marsh for foraging and roosting at this time. The primary goals of this project were to establish permanent survey locations within Sweetwater Marsh, to contribute to the data collection in regional bat studies, and to establish a site-specific bat habitat threat reduction and management plan based on the survey results.

Very little information exists on the status or distribution of either species, particularly in the North County MSCP area. Therefore, San Diego County-wide surveys for these species were needed to document where they were found and what their current population status was. Obtaining this information would allow for more informed consideration of the conservation planning and management of these species in the North County plan. This would also allow habitat models to be developed for the target species to aid in future planning.