Hibernation

From Conservapedia

Hibernation is a behaviour of certain animals, particularly in cold climates, of entering a prolonged physically inactive state of lowered metabolic activity, as a means of coping with the vicissitudes of winter. While many animals will sleep more than usual during the winter, true hibernation involves dramatically reduced heartrates and body temperatures, generally over a single unbroken period of torpor.

Animals that hibernate include bears, the dormouse, the hedgehog, and many types of reptiles and amphibians.

Most birds use Animal migration to avoid harsh seasonal conditions; the common poorwill, a type of nightjar, is the only bird known to hibernate. Historically, swallows were believed to hibernate at the bottom of ponds.

Animals which become inactive in summer are said to aestivate.