Do Bears Hibernate?
Bears over-winter by sleeping in caves and burrows. Their core-body temperatures drop 3-5 degrees Celsius.
Three to five Celsius is a small change in core-body temperature compared with other species that undergo up to 32 degree changes during hibernation.
Because the core-body temperature of bears doesn’t drop as much as other hibernators, it is still debated whether bears really hibernate.
But the prevailing opinion is that bears do hibernate.
The 3-5 degree change represents a lower metabolic rate of up to 75 percent lower than bears’ basal metabolic rate.
The definition of hibernation is not the degree of temperature change. Hibernation is defined by metabolic suppression.
Bears’ metabolisms are suppressed during the over-wintering period.
Bears in the most northerly regions will not eat or drink for up to eight months, and rely only on stored body-fat for energy and water–metabolic suppression allows this.
Bears’ bodies also recycle proteins and urine during over-wintering, so bears do not suffer muscle atrophy and do not need to urinate for months.
Anyone interested in some hard science? Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature
Title photo by: Doug Brown
Do Bears Hibernate?
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