Last week I wrote about migration as a strategy for surviving the colder temperatures and food shortages during the winter. However, a number of other animal species have instead evolved to use winter dormancy to make it through the winter.
Hibernation is a type of winter dormancy typically employed by mammals. Other species such as birds, fish, reptiles, and amphibians undergo other types of winter dormancy (also called torpor) to get through the winter and other metabolically-stressful periods.
During hibernation, an animal’s metabolic rate, breathing, and heartbeat are suppressed, increasing their tolerance to the cold. Hibernation ensures survival by conserving energy during a period when food is scarce.
Hibernating animals still need some energy to fuel their bodies’ basic needs while they are dormant. So, similar to migration, animals must either eat a great deal prior to hibernation in order to store up enough fat to get them through the whole winter, or they must store food near their den and wake periodically to feed. The latter technique is used more by smaller animals such as squirrels, whose small body size makes it difficult to store large amounts of fat. You can support hibernating animals by planting native food sources, especially plants that produce berries, nuts, acorns, seeds, and other fruits.
Hibernation leaves an animal vulnerable to predation, so animals must find safe places to hibernate, such as caves, tree cavities, and nest boxes. However, for some species like bats, it also leaves them vulnerable to disease. In North America, bats that hibernate in caves are threatened by a disease called white-nose syndrome. This disease is caused by a fungus (Geomyces destructans) that thrives in the cool, damp climates found inside caves, and is devastating bat species such as the little brown myotis. The disease causes bats to wake too frequently during the winter, using their energetic reserves too quickly before they can refuel on insects in the spring. If you have bats hibernating in a cave on your land, you can help prevent the spread of white-nose syndrome by entering the cave as infrequently as possible, and following proper decontamination procedures when visiting the cave is necessary.
For information on specific ways that you can help cave-hibernating bats on your land, or for recommendations on specific species you can plant for hibernating mammals, contact WHC at WHC@wildlifehc.org.