Plecotus townsendii virginianus — Overview

Virginia Big-eared Bat learn more about names for this taxon

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The Virginia big-eared bat (Plecotus townsendii virginianus) is a medium-sized (3-4 in or 8.5-10cm long) colonial vesper bat (family Versperidae) with ears more than 1 inch (2.5cm) long.  In 2005 P. t. virginianus officially became the state bat of Virginia.  These bats are non-migratory and roost exclusively in limestone caves summer and winter.  Surveys in 2009 revealed that Virgina big-eared bats roost in just 15 caves in the Appalachian mountains of eastern Kentucky, eastern West Virginia, southwest Virginia and northwestern North Carolina, and estimated a total hibernating population of about 12,000 for the subspecies (Stihler 2011).  Over the winter, the bats congregate in hibernation sites (hibernacula) in dense mixed-sex clusters near the entrance or in well-ventilated parts of caves where temperatures stay above 32 degrees F (0 degrees C).  The bats mate in the fall and winter, sometimes while females are still in a torpid state.  Females store the sperm, ovulate in the spring, and then disperse in summer to maternity colonies where they give birth to a single offspring.  Mothers provide care and nurse their young until they mature at 6-8 weeks of age.  Virginia big-eared bats are insectivores and feed only at night; a majority of their diet is moths (US Fish and Wildlife Service 2013; Virginia Department of Game and Inland Fisheries 2013; Lacki and Dodd 2011; Loeb, Lacki and Miller 2011).

Virginia big-eared bats and their close relatives the Ozark big-eared bats (P. t. ingens) are remnant populations disjunct from each other and from the other two more populous subspecies of Townsend’s big eared bats (P. t. pallescens and P. t. townsendii), which have large ranges across the western half of the United States.  The eastern subspecies are thought to have diverged from the western populations during the ice age and research groups are investigating whether these subspecies should be considered separate species.  There is also evidence for recognizing and managing the colonies within the Virginia big-eared bat subspecies as evolutionarily distinct units, since the colonies are isolated and probably do not interbreed (Lack and Van Den Bussche 2009; Piaggio and Perkins 2005; Bayless et al. 2011).  Both eastern subspecies are federally listed as endangered and listed as imperiled by NatureServe due to their small, restricted populations and vulnerability to human disturbances. 

Spelunking (caving), vandalism and intruding humans are currently the major threats to the Virginia big-eared bat, as a whole colony can easily abandon their cave and offspring when disturbed.  Furthermore, when aroused in winter the unplanned increase in body temperature uses up the limited energy reserves required to last their full hibernation period.  Other threats to these bats are decline of insect food sources as a result of pesticide use and human development and mining activities reducing already limited number of appropriate roosting/breeding caves and foraging areas (Virginia Department of Game and Inland Fisheries 2013; Bayless et al. 2011).  Virginia big-eared bats roost in caves known to contain other species of bats afflicted with white nose syndrome (WNS), a fungus-related illness that has been decimating North American bat species since 2006.  Although infection could have particularly damaging ramifications to Virginia big-eared bats, they do not seem to be affected by this disease yet (Douglas 2008; Platt 2012; Youngbaer 2013; Gomez 2010).  The National Zoo attempted to protect Virginia big-eared bats from WNS in 2010, a controversial project (Smithsonian Newsdesk 2010).

The Virginia big-eared bat is confusable with closely related Rafinesque’s bat (Corynorhinus rafinesquii), which has an overlapping range.  Townsend’s big-eared bat subspecies have a history of taxonomic name changes and are known by generic names Corynorhinus, Synotus, and Plecotus.  Recent molecular work differentiates the new world species as Corynorhinus and old world species as Plecotus (Gruver and Keinath 2003).


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