Big Brown Bats
(Eptesicus fuscus)
Big brown bats (Eptesicus fuscus) are a non-migratory species that will roost in both natural and man-made structures. For their hibernation sites, they prefer subterranean areas like caves and mines because of the temperature stability they offer. For the rest of the year, they can be found in rock crevices, tree cavities, homes, barns, and caves. They have shown an ability to survive up to 19 years in the wild.
They are insectivores that will prey on wasps, dragonflies, moths, and beetles. They mate in the fall before they go into hibernation and the females will birth their young in the late spring and early summer. The females will separate from the males to form maternity colonies and they will all roost together again in the late summer once the young are weaned.
They are brown to reddish brown in color with lighter shades on their underside. They reach lengths of around 4 ½ to 5 ½ inches long and a wingspan of about 13 inches. They are sexually dimorphic, meaning that the females will grow to slightly larger sizes than the males of the species. Their native range spreads from southern Canada, the United States, into Central and northern South America.
