In areas where winters are especially cold and harsh, certain animals have adapted to survive the chilliest conditions by hibernating. But as available hibernation sites may be limited in these zones, some species gather together in dens, caves, trees, cavities and burrows to fall into a deep winter slumber. By slipping into a state of dormancy, these creatures feed on their fat reserves for several months.
Some snake species – such as copperheads, garter snakes and even some rattlesnake varieties – migrate to the same den each winter to hibernate with other snakes. This appears to be more common in areas where the frost line is deep, such as Alaska and British Columbia.
There’s evidence in Alaska that flying squirrels congregate in the interior cavities of white spruce trees to sleep through the coldest months of the year.
And it’s been documented that spotted turtles (Clemmys guttata) hibernate in communities; some of these turtles even wintered in the same hibernacula multiple times. Research also revealed that while hibernating, a spotted turtle was protected from freezing.
In the Rocky Mountain tundra, yellow-bellied marmots endure winter by entering a burrow with their colony. During hibernation, this animal drops its body temperature to less than 40 degrees Farenheit, and its heart beats just once per minute.
Other animal species that will periodically hibernate in groups include squirrels, bats and badgers.
Want to learn more about how animals cope with harsh winter conditions? Check out this blog post on the wildlife of Yellowstone National Park.