In winter, bats go into hibernation. Hibernation is an extended period of deep sleep (or torpor) that allows animals to survive cold winters with harsh weather. A bat’s body temperature lowers and their metabolic rate slows, meaning they use less energy and can survive on the fat they have stored up instead of trying to forage for food. During hibernation, bats need roosts that are cool and remain at a constant temperature. They often move into underground sites, such as caves.
- Pipistrelles are our most common bats, but we don’t know where they all go in winter! We have not found enough hibernation roosts to account for the numbers we see in the summer months.
- Bats mate during the autumn and sometimes into the winter when they hibernate. The females then store the sperm and do not become pregnant until the spring.
- In North America, white-nose syndrome has been associated with the deaths of 5.5 million bats since 2006. The fungus grows on hibernating bats, irritating and possibly dehydrating them so they wake up. Being aroused from hibernation costs the bats a lot of energy, which makes them lose body fat and can lead to starvation.