The Physiology of Overwintering in Black Bears (Ursus americanus)

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Overwintering in black bears has been described as “a physiological and metabolic marvel” and continues to fascinate scientists who want to understand the unique mechanisms of bear hibernation (Nelson, 1973). Though not “true hibernators,” bears are one of the animals most commonly associated with hibernation (Svihla, 1954). This website is designed to review some of the physiological mechanisms and consequences of the overwintering period that allows black bears (Ursus americanus) to spend 3-7 months without food or water while maintaining a body temperature around 34° Celsius. Even more fascinating about these animals is their ability give birth and nurse while overwintering, yet they never excrete urine or feces during this time (Nelson, 1973; Nelson, 1980). While there is still much to be learned about this period of winter torpor, much is already known and can distinguish bears from other mammalian hibernators.


*All pictures on this site are courtesy of Corel unless otherwise noted*

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This website was created as a part of a class project in the Animal Physiology Class at Davidson College