The mere sight of a bat can cause fear in some people. Bats are misunderstood and interesting creatures that fly at night. They sleep during the day and, in some cases, hibernate during the winter.
Migration vs. Hibernation
Some species of bats, such as the little brown bat, hibernate. Others, like the silver-haired bat, migrate to warmer climates. There are also species that migrate to warmer areas then go into hibernation.
Most bats that hibernate during the winter spend their long sleep in caves or mines. Bats may also seek shelter in homes or barns then enter a state of hibernation.
During hibernation, a bat's metabolic activities are reduced, so its body temperature is reduced and its heart rate slows. According to the Center for Ecology and Conservation Biology, a bat's heart rate during hibernation can be as little as 20 beats per minute, compared with almost 600 beats per minute in an alert but resting state.
A hibernating bat must rely on its body's fat reserve for nourishment. A hibernating bat can survive on a few grams of fat for a period of five to six months, according to the U.S. Fish and Wildlife Service.
Bats can lose from 1/4 to 1/2 of their body weight during hibernation. If a bat is disturbed two or three times during hibernation, it can expend too much energy and die.