Little Brown Bat

Description:  This is a small to medium-sized bat is about 3½ inches in length, with a wingspan of about 10 inches. The upperparts vary from medium brown to buffy brown, and the fur is relatively glossy. The belly fur is light gray-brown to buffy-brown, typically contrasting sharply with the color of the upperparts. Little brown bats have a short, blunt-tipped tragus, no keel on the calcar, and especially long toe hairs that extend beyond the tips of the toes.

Range:  This species occurs across most of North America from central Alaska and Canada, south through much of California, central Arizona, through the Rocky Mountains into Mexico, and most of the southeastern United States; it is largely absent from the southern Great Plains and much of the southeastern Coastal Plain.

Kentucky Occurrence Summary:  The little brown bat occurs throughout, although it is locally distributed in heavily forested parts of the state in summer and is restricted to areas with caves in winter.

Distribution in Kentucky:See map

Habitat and Life History:  The little brown is a widespread bat that has adapted fairly well to the presence of humans. Not surprisingly, it is one of the bats most often encountered by humans. It hibernates primarily in caves, but a few can be found in mines and underground quarries with suitable temperatures. These bats seem to prefer slightly warmer and moister areas of caves in which to hibernate than most other species of Myotis bats occurring in Kentucky. They also do not roost in tight clusters; instead they are often observed hanging singly, in rows along cracks in the rock, or in loose clusters. Little brown bats are migratory, and most of the individuals that hibernate in Kentucky caves probably go farther north for the summer. In turn, some of our wintering little browns and ones from farther south likely make up Kentucky’s summer population. Like most other bats, upon leaving their hibernacula females typically gather at maternity colonies, some of which may be composed of several hundred or more individuals. Prior to human settlement, it is believed that little brown bats used hollow trees for summer roosts; however, today most known sites are in barns and buildings, typically in very warm, secluded areas like attics. Each female bears a single pup in June, and the young are on the wing within about three weeks. Some males may roost with the females, but most apparently roost separately, using a variety of sites including buildings, bridges, tree cavities and loose bark of snags. Little brown bats forage in a great variety of habitats from woodland edge and stream corridors, to parks and suburban yards. They feed mostly on small, flying insects. 

Threats: The main threat to this species is white-nose syndrome, a devastating disease found in North America that is caused by a “cold-loving” fungus. It has caused unprecedented mortality in some of our hibernating bat species like the little brown bat, especially in the northeastern U.S.