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How do hibernating mammals prepare for long periods without food?

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Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

To prepare for long periods without food, hibernating mammals undergo significant physiological and behavioral changes driven by environmental cues like shorter days and cooling temperatures.1

Feeding and Energy Storage

In the fall, hibernators consume large amounts of food to build substantial stores of body fat. This includes both white adipose tissue, which serves as a long-term energy reserve, and brown adipose tissue. Brown fat is particularly vital, as it generates heat to support the animal during arousal from dormancy. Some species also store food within their dens to consume during brief periods of wakefulness.123

Physiological Adaptations

To survive on these energy stores, hibernators enter a state of dormancy characterized by:
* Metabolic Suppression: The animal reduces its metabolic rate to the minimum level necessary to sustain life.4
* Temperature Regulation: True hibernators allow their body temperature to drop, often nearing the ambient temperature of their environment.4
* Circulatory Changes: Heart rates and respiration slow dramatically, sometimes to only a few breaths or heartbeats per minute.154

These adaptations allow animals to conserve energy, though the process remains a precarious survival strategy.4