Bats like to roost in secluded, warm locations, such as under loose tree bark or in quiet attics or neglected buildings. Females often roost together in maternity colonies, where young bats are born and raised. Their young are born between May and June; they usually have one at a time but will occasionally have two. The females leave the roost at night to forage, but the young do not leave until they are old enough to forage on their own, which is usually after about three weeks.
As winter approaches and the insect supply diminishes, bats migrate to caves, where they enter a state of “torpor,” or decreased activity. Their heartrates can drop from over a thousand beats per minute to one beat every four or five seconds, which allows them to survive for months on very little fat.