Big Brown Bat
- Scientific Name: Eptesicus fuscus
- Weight: 11-23 grams
- Wingspan: 32-35centimeters
- Distribution: From southern Canada throughout the United States to northwestern South America, including many islands in the Caribbean.
- Ecology and Behavior: Big brown bats are closely associated with humans and are probably more familiar to people in the United States than is any other species of bat. Most summer roosts are located in attics, barns, bridges or other man- made structures, where colonies of a few to several hundred individuals gather to form maternity colonies. They move into caves, mines, and other underground structures to hibernate only during the coldest weather. Where most of these bats stay during winter remains unknown. This species emerges at dusk and flies a steady nearly strait course at a height of 6-10 meters. Its large size and steady flight make it easily recognizable. Apparently, some individuals use the same feeding ground each night, for a bat can be seen following an identical feeding pattern on different nights. After feeding, the bat flies to a night roost to rest: favored night roosts include the porches of stucco or brick houses, garages with open doors, or a breeze way.
- Food Habits: These bats consume beetles, ants, flies, mosquitoes, mayflies, stoneflies, and a variety of other insects.
- Reproduction: Mating takes place in autumn and winter, females store sperm, and fertilization takes place in spring. In the eastern United States, big brown bats usually bear twins in early June. In western North America, only one young is born each year.
- Status of Populations: Relatively common throughout most of its range.
The presence of species in particular counties is based on both summer and winter occurrence records compiled by the TNBWG, an unshaded county does not represent the absence of a particular species from that county, only the lack of an occurrence record. These maps are intended for educational and general information purposes only and are not intended for use in consultation with US Fish and Wildlife Service (USFWS) or any other state or federal agencies. Project proponents should contact USFWS and the Tennessee Wildlife Resources Agency for the most up to date ranges for bat species in Tennessee.
Range Map Data Sources
National bat ranges - Layer downloaded from nationalatlas.gov. The data were compiled by Bat Conservation International using data from state natural heritage programs, published literature, unpublished reports, museum collections, and personal communications from university, Federal, State, and local biologists.
TN county occurrence data - TWRA Scientific Collection Permit data compiled from 2000-2013, TWRA Wildlife Diversity database, published literature [Graves and Harvey 1974. (Journal of the Tennessee Academy of Sciences 49:106-109)], personal communications from university, Federal, State, local biologists, and TNBWG members.