BAT INVENTORY AT ASSATEAGUE ISLAND NATIONAL SEASHORE
Natural Resource Technical Report NPS/NCBN/NRTR—2010/284

J. Edward Gates
Appalachian Laboratory
University of Maryland Center for Environmental Science (UMCES)
301 Braddock Road
Frostburg, Maryland 21532

Joshua B. Johnson
Appalachian Laboratory
University of Maryland Center for Environmental Science (UMCES)
301 Braddock Road
Frostburg, Maryland 21532

January 2010

U.S. Department of the Interior
National Park Service
Natural Resource Program Center
Fort Collins, Colorado
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Project Highlights

Eastern red bats (Lasiurus borealis) are the dominant bat species at Assateague Island National Seashore (ASIS). We positively identified 4 other bat species, including, in decreasing order of frequency, big brown bats (Eptesicus fuscus), hoary bats (L. cinereus), eastern pipistrelles (Pipistrellus subflavus), and silver-haired bats (Lasionycteris noctivagans). We captured 2 bats that we identified in the field as Seminole bats (Lasiurus seminolus), which would be the first records of this species in Maryland. However, based on our photographic evidence and morphological measurements, wildlife professionals were divided in their identification of this species, with some speculating that both bats could have been dark-morph red bats. Without confirmation by genetic analysis, our captures of Seminole bats remain debatable. All other species inventoried at ASIS are considered common throughout their ranges. Some bat species migrate through ASIS, and others, including eastern red bats and big brown bats, produce and raise offspring during the summer months at ASIS. Inventories of bat species were most successfully accomplished by long-term monitoring with bat detectors. Bat activity was inconsistently predicted by weather conditions depending on season. Bats were most active from April–December. There was more bat activity in the loblolly forests and at freshwater pools than at bayside marshes, shrub/dune zones, and beaches during summer. We found no evidence of bats roosting in abandoned structures that we examined on the island. Bats use ASIS in a variety of ways, including as a place to produce and raise offspring during summer, a stopover site during spring and autumn migration, and some bats over winter at ASIS. Low bat species richness and diversity at ASIS likely is a result of low roost diversity, i.e., the loblolly pine (Pinus taeda) monoculture, and long distances to hibernacula west of the Blue Ridge physiographic province.

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