Because some bats hibernate in buildings during the winter months, batproof a building only when you are sure no bats are hibernating in it. In the spring, disturbing a maternity colony when flightless young are present may cause young bats to be dropped to their deaths, or abandoned, by panicked females. It is important not to disturb roosting bats at any time of the year. Thus, if disturbed multiple times, hibernating bats may starve to death before spring. A single disturbance probably costs a bat as much energy as it would normally expend in two to three weeks hibernating. If a bat rouses early from hibernation, it must use its fat reserves to increase its body temperature. It is important not to disturb hibernating bats. Hibernation lasts until April or early May, but in coastal regions bats may arouse in late winter-little brown bats have been found feeding in the Puget Sound region in mid-March. Still, there are some species, such as the big brown bat, that can hibernate in relatively exposed situations in buildings where there is considerable fluctuation in temperature. They select areas in the hibernaculum where there is high humidity (70–95 percent), and the temperature is 34 to 41 degrees F.

Bats often hibernate in groups called colonies. They often seek shelter in the attics of homes where the temperature is suitable for hibernation. Bats hibernate from October or November through March or April.

A hibernating bat can thus survive on only a few grams of stored fat during the five- to six-month hibernation period.īanding studies indicate that little brown bats will migrate 120 miles between hibernacula and summer roosts, and, if undisturbed, they occupy the same site year after year. Now that fall is here, many animals are looking for warm places to hibernate for the winter. During hibernation, metabolic activities are greatly reduced-a bat's normal body temperature of around 100 degrees F is reduced to just one or two degrees higher than that of the hibernaculum, and their heart rate slows to only one beat every four or five seconds. With few flying insects available to them during winter in Washington, bats survive by hibernating, migrating to regions where insects are available, or a combination of these strategies.

Bats hibernate in winter