Hibernation is a state of minimal activity and metabolic depression that some animal species undergo, primarily to survive the winter months. Characterized by low body temperature, slow breathing, heart rate, and reduced metabolic rate, hibernation helps conserve energy when food is scarce.
Although traditionally associated with “deep” hibernators like rodents, the term now includes animals such as bears, based on metabolic suppression rather than a significant drop in body temperature. Some mammals hibernate while pregnant, such as female black bears, which gain weight to support their cubs during this time.
Ectothermic animals also experience dormancy, often referred to as diapause. While many insects exhibit winter dormancy, the term “brumate” is sometimes used for reptiles, though “hibernation” is commonly applied to all winter dormancy states.
Hibernators are classified as obligate or facultative. Obligate hibernators, like ground squirrels and hedgehogs, enter hibernation annually regardless of environmental conditions. They experience periods of torpor interrupted by brief arousals, the reasons for which remain unclear. Hypotheses suggest these arousals may help recover from sleep debt or restore energy levels.
Facultative hibernators, on the other hand, enter hibernation in response to cold stress or food scarcity. This classification highlights the different ways animals adapt to seasonal changes.
