Summary

Bats were inventoried within 11 National Capital Region National Parks during 2003- 2005, using mist nets, harp traps, and bat detectors in fields, forests, riparian zones, and caves.

Efforts included 365 mist net/harp trap nights at 74 sites and 362 sites monitored with Anabat II bat detectors. Buildings, bridges, caves, mines, and tunnels were searched for hibernating bats. Six species, of bats were captured, including 149 big brown bats (Eptesicus fuscus), 63 eastern red bats (Lasiurus borealis), 3 hoary bats (L. cinereus), 109 little brown bats (Myotis lucifugus), 26 northern myotis (M. septentrionalis), and 33 eastern pipistrelles (Pipistrellus subflavus).

Acoustic monitoring consistently detected all species captured in mist nets and species that were not captured, therefore providing a more complete documentation of bat communities. NCR National Parks contained habitat suitable for most bat species common in the Mid-Atlantic region. Reproduction and recruitment occurred at most NCR National Parks, but varied among species and parks. Big brown bats were the most ubiquitous and probably the most abundant bat at NCR National Parks. Northern myotis, and to a lesser extent, little brown bats, were not as prevalent in urban parks, which may be a result of forest fragmentation within parks or surrounding areas, or consequence of surrounding development. Urban parks are farther from hibernacula and may be on the periphery of little brown bat and northern myotis summer ranges. Forested urban parks that were similar distances from hibernacula produced more little brown bat and northern myotis activity than fragmented urban parks. The majority of hibernating bats were big brown bats; most were located in tunnels.

Although no rare or endangered bats were documented, historic records of eastern small-footed bats and Indiana bats occurred on nearby properties, indicating that these species could occur in low numbers in some parks.