Big Brown Bat (Eptesicus fuscus)

big brown bat

Physical Description

As their name describes, they are one of the largest bats found in the state of Kentucky. They can reach sizes of 5 inches long and a wingspan of 13 inches or more. They are a glossy brown and lighter color underneath. They are also characterized by a hairless snout and a keeled calcar.

Range and Presence in Kentucky

These bats have an enormous range that extends from central Canada all the way down through northern South America. They are a year-round resident of the state of Kentucky. It is likely that they travel short distances between summer and winter roosts. It has been found that they seem to be absent from the Mississippi Alluvial Plain in the western part of Kentucky.

Habitat and Behavior

When people come into contact with bats, this is usually the species that they encounter. The big brown bat is a species that has adapted well to the presence of people. They normally roost in man-made structures, like abandoned buildings, attics, barns, and even the eaves of buildings. During hibernation, they prefer the environment that caves provide and will do so in the coldest part of the caves near the entrance in rock crevices.

The maternity colonies of big brown bats are even found in buildings or under bridges. They can consist of up to 100 females and each female usually gives birth to twins in early June. During this time, the males will roost solitarily and away from the maternity colonies.

Big brown bats are insectivores and have been referred to as “friends of farmers” because they will eat insects that can cause serious damage to their crops. They also forage in a lot of other areas that are open, semi-open, and even around streetlights.


Although they have adapted well to people, there are still threats to the populations, like white-nose syndrome. These bats have seen serious number decreases in the northeastern United States as a result of deaths due to white-nose syndrome.

Bat Species

Rafinesque’s big-eared bat
Silver-haired bat
Seminole bat
Little brown bat
Indiana bat
Virginia big-eared bat
Red bat
Gray bat
Eastern small-footed myotis
Evening bat
Hoary bat
Southeastern myotis
Northern bat
Eastern pipistrelle

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