Big Brown Bat

The big brown bat is nocturnal, roosting in sheltered places during the day. It will utilize a wide variety of structures for roosts, including mines, caves, tunnels, buildings, bat boxes, tree cavities, storm drains, wood piles, and rock crevices. They generally roost in cavities, though they can sometimes be found under exfoliating bark. Female big brown bats form maternity colonies to rear young. The size of these colonies can vary from 5 to 700 animals. Males of the species roost alone or in small groups during this time. Both sexes will roost together again in the late summer. Big brown bats enter into hibernation around November, often in a location less than 80 km (50 mi) away from their summer roosts.