One fact about bat hibernation is that only some species of bats hibernate in winter. While other bat species migrate to warmer climates because of scarcity of food, some seek shelter in places protected from elements, go in a state of torpor and hibernate. The few species of bats that hibernate can survive the subfreezing temperature and can even tolerate being encased in ice.
Another fact is that most hibernating bats move to isolated houses, caves or abandoned mines where they are protected and there is less chance of encountering their predators. During their hibernation, bats are usually found clustered on cave ceilings or walls. They slow down their bodily functions, such as heart rate, metabolism and breathing levels to extremely low levels in order to regulate their temperature. In a state of torpor, a bat's heart rate can be as low as 10 beats per minute; a tremendously low count when compared with the rate of almost 600 bpm when awake and 1,300 bpm when in flight.
Like other hibernating mammals, bats spontaneously arouse momentarily from torpor in warmer periods in winter. These periods of arousal are also a way to eliminate metabolites, urine or to adjust their temperatures. Bats may also be awaken due to human intervention.
Hibernating bats are extremely good in surviving freezing weather. While other mammals can die if their temperatures reach 10 degree Celsius, bats survive in weather as low as zero degree Celsius. At the end of the hibernation period, they can rewarm their bodies without using external sources through internally created heat, a common thing among hibernators.