Big Brown Bat

Eptesicus fuscus

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  • Big Brown Bat |  Photo: Ann Froschauer, USFWS
  • Big Brown Bat |  Photo: Ann Froschauer, USFWS
  • Big Brown Bat |  Photo: Ann Froschauer, USFWS by v8.6m

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Basic Information






Big Brown Bats are generally between 4 and 5 inches in length.


up to 19 years


Big Brown Bat (Eptesicus fuscus) facts, habitat, diet, range, bat pictures and more to help you learn to identify the bat.




Big Brown Bats breed from late fall through late winter. Females enter nursery colonies after insemination, however they do not become pregnant until the spring. They store the sperm through hibernation. Pups are born helpless, but quickly grow and are able to fly within six weeks.



Number of Offspring

2 pups


11-14 in

What does the Big Brown Bat look like?

Big Brown Bats are overall, as their name suggests brown. Their coloration can vary with location however, from a pinkish tan to dark chocolate browns. Their wings, faces, ears and tails are naked and blackish in coloration. They have large heads compared to their slender bodies that contain 32 razor sharp teeth.

Big Brown Bat Habitat

Open Forests, Caves

Big Brown Bat Facts

Big Brown Bats are large nocturnal bats that are widespread across North America. They are hardy and can live in places where other bats could not survive. They roost during the days in hollow trees, caves, and rock crevices or in buildings. They travel the night skies in search of insects using echolocation, which means they produce ultrasonic sounds and listen for the echo's to return. There are at least three different subspecies of Big Brown Bats. They are insectivorous, thus feed on night-flying insects such as moths, beetles and wasps, all of which they capture in flight. They spend the winter months hibernating and will migrate a short distance to find a suitable roost. Big Brown Bats also produce sounds humans can hear during flight, listen for a clicking or the sound of escaping steam when taking a twilight hike.

See also