Academic journal article The American Midland Naturalist

Bats of Assateague Island National Seashore, Maryland

Academic journal article The American Midland Naturalist

Bats of Assateague Island National Seashore, Maryland

Article excerpt

ABSTRACT. -

As significant nocturnal insectivores, bats are an integral part of many ecosystems. Determining bat species composition in an area is a critical first step in managing for this important resource. Little information exists concerning the bat species composition of Maryland's Coastal Plain, which is located on the northern periphery of the geographic ranges of five bat species occurring in the southeastern United States. We conducted mist net surveys for bats at Assateague Island National Seashore, a barrier island on Maryland's coast, in summer 2005 and summer and autumn 2006. In 2005 we captured 133 bats representing three species, including two big brown bats (Eptesicus fuscus), 129 eastern red bats (Lasiurus borealis) and two purported Seminole bats (L. seminolus) . In 2006 we captured 60 eastern red bats in summer and autumn combined. We used Anabat II bat detectors to conduct long-term acoustic monitoring on the island year round and documented three additional bat species, including silver-haired bats (Lasionycteris noctivagans) , hoary bats (Z. cinereus) and eastern pipistrelles (Pipistrellus subflavus). We documented silver-haired bats during spring and autumn, probably as they were migrating through the area. We used Anabat II bat detectors to conduct short-term monitoring of bat activity at five habitat types during summer 2005 and 2006 and found that total bat activity and eastern red bat activity were similar among forested areas, freshwater pools and bayside marshes. In shrublands, total bat activity and eastern red bat activity was higher than at beach areas, lower than in forested areas and similar at freshwater pools and bayside marshes. The loblolly pine (Pinus taeda) - dominated forests at ASIS provide roosting and foraging habitat mostly for eastern red bats, but also for other migratory bat species.

INTRODUCTION

Much recent attention has focused on the conservation and management of bats because of their roles in ecosystems and as possible indicator species (Fenton, 2003; Miller et al, 2003). However, to make informed management decisions regarding bats, collecting baseline inventory data is a necessary initial undertaking. Aldiough a general assessment of bat species composition for a given area can be determined by examining published geographic ranges, verifying die presence and relative frequency of species through an inventory process facilitates more informed and accurate management decisions. Moreover, baseline inventories may be especially useful in areas located on peripheries of geographic ranges. For example, the bat community composition on Maryland's Coastal Plain may be more similar to those of the southeastern United States than to diose of the Appalachian Mountains (Limpert et al, 2007) . Some bat species, including northern yellow bats (Lasiurus intermedins) and Seminole bats (L. seminolus), have geographic ranges with nordiern limits extending into Virginia, and a few extralimital records in Pennsylvania, New Jersey and New York (Poole, 1932, 1949; Layne, 1955; Koopman, 1965). There are accounts of Rafinesque's big-eared bats (Corynorhinus rafinesquii), southeastern myotis (Myotis austroriparius) and Brazilian free-tailed bats (Tadarida brasiliensis) occurring as far north as southeastern Virginia (VADGIF, 2005).

The distribution of bats and species composition in a region is positively associated with an increase in roost diversity (Humphrey, 1975). Maryland has diverse geology and flora, from the northern hardwoods forest association on the Appalachian Plateaus physiographic province in the west, to the loblolly pine (Pinus taeda) -dominated forests of the Coastal Plain in the east (Schmidt, 1993). In Maryland, 10 bat species were documented, including big brown bats (Eptesicus fuscus), silver-haired bats (Lasionycteris noctivagans) , eastern red bats (Lasiurus borealis), hoary bats (L. änereus), eastern small-footed myotis (Myotis leibii), little brown myotis (M. …

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