Do Bats Hibernate?

A group of lesser horseshoe bats hibernating in a cave.

Bats are the only mammals that have the true ability to fly. Their forelimbs are adapted into wings which can naturally sustain flight. Bats belong to the order Chiroptera, which is the second largest order of mammals, and accounts for about 20% of all mammal species, with roughly 1,200 species. Bats are traditionally sub-divided into two sub-orders: echolocating microbats and fruit-eating megabats. However, bats have recently been divided into Yinqterochiroptera, which includes megabats and certain species of microbats, and Yangochiroptera. Most species of bats are insectivorous, while others are frugivores, meaning that they feed on fruits. Additionally, other species, such as the vampire bat, feed on blood. Bats are primarily nocturnal animals and prefer dark places during the day, such as caves. Bats live throughout the world, except in extremely cold regions.

Do Bats Hibernate?

In addition to being nocturnal animals, some species of bats are known to go into hibernation, especially during the cold winter season. Not all bat species hibernate, but those that do are species that live in high altitude areas where food becomes scarce during the cold winter season. During the period of hibernation, bats can be found in clusters on ceilings and cave walls, curled up like balls. Hibernation is simply a period of extended deep sleep for bats, also referred to as torpor. This period allows the animals to survive the cold harsh winter season. Bats begin to hibernate in November and remain inactive until approximately mid-May. While in the state of torpor, a bat's body temperature falls and its rate of metabolism slows. Thus, a hibernating bat uses little energy and can survive on stored fats rather than spending energy searching for food. Interestingly, a bat's heart rate drops to about 4 beats/minute during hibernation, which is an impressive drop considering that its heart rate can reach 1,000 beats/minute while flying.

Where Do Bats Hibernate?

As winter approaches, bats begin to look for a comfortable place to roost, a place where they can hibernate during the cold season. Some bats also migrate to warmer areas where they hope to remain active rather than hibernate. Bats cannot build nests or bore holes in the ground, so they utilize any gap they can find. Rocks, caves, and homes are some of the common places in which bats will hibernate during the winter. Some species also hide in hollow trees or cavities bored by other animals, such as woodpeckers. Old and abandoned barns are also favorite spots for bats. They may also crawl into small rock crevices and squeeze themselves into unusual positions, such as lying on their heads.

Most bats generally remain dormant and move as little as possible during hibernation in order to use as little stored fats as possible. However, when disturbed by sudden lights, loud noise, or increased temperature, bats may fly around in search of food. If unable to find food, the bat may starve to death. Bats that hibernate in homes may carry parasites, such as ticks and fleas, that can spread throughout the home. Of the bats that hibernate in homes, big brown bats are the most troublesome.


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