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Photo Credit: Audrey Holstead

Big brown bat

Eptesicus fuscus

Order: Chiroptera

Suborder: Yangochiroptera

Family: Vespertilionidae

Call characteristics:

Low frequency caller (~30 kHz range)

Body Length

3 3/8 - 5 3/8 in (8.7 - 13.8 cm)


1/2 - 3/4 oz

(14 - 20 g)

Big brown bats are medium brown in color, with darker facial features and ears. Their small ears and eyes sit upon a blunt face. This bat can be seen in urban and suburban environments of mixed agricultural use. As generalists, the species can be at home among timberline meadows to lowland deserts, and abundant in deciduous forest areas. Big brown bats will roost in artificial structures, including buildings, bridges, and bat houses. When selecting for hibernation roosts, this species can tolerate hibernating in areas that experience very cold temperatures. Big brown bats have a preference for munching on beetles but will eat a variety of insects. Females can consume up to their body weight in insects in a single night. In the west half of this species' range, females have been found to produce a single pup (baby bat), whereas twins are more frequent in the east.

Conservation Status

U.S. FWS - not listed
Canada - not listed
Mexico - not listed


There are various sources for bat species range maps including IUCN, NatureServe, U.S. Fish and Wildlife Service ECOS, and the National Atlas of the United States (left). 




NABat utilizes monitoring data provided by a broad network of partners to support regional and range-wide inferences about changes in the distributions and abundances of bat populations facing current and emerging threats.

In Development

Information used to populate this page was obtained from the following sources:


NatureServe Explorer

United States Fish and Wildlife Service Environmental Conservation Online System 

Bat Conservation International Bat Profiles

National Atlas of the United States. (2011). North American Bat Ranges, 1830-2008. National Atlas of the United States. Available at:

Taylor, M. 2019. Bats: an illustrated guide to all species. Washington, DC: Smithsonian Books.

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