Myth Debunked: Do bears really hibernate?
They fall into a deep sleep called torpor
We have all watched the Yogi Bear show, which perhaps seeded the idea that bears hibernate during the cold months. This is not 100 per cent scientifically accurate.
Hibernation is a voluntary state an animal enters to conserve energy, when food is scarce, and minimise exposure to the winter elements.
Hibernation is characterised by three key physiological changes: a reduced metabolism, a slower heart rate and a lowered body temperature. Hibernation can last days, weeks or months, depending on the species.
While many people think bears are hibernators, they actually participate in a similar, though not exact, practice. Instead of hibernating, bears fall into a deep sleep called torpor.
During torpor, heart rate and breathing rate decreases (but not as much as that of true hibernators), body temperature reduces slightly, and bears do not eat or release bodily waste. Bears can sleep more than 100 days without eating, drinking or passing waste. Instead, bears are able to literally turn their pee into protein through a urea-recycling process. The urea produced by their fat metabolism is broken down and the nitrogen is reused by the bear to rebuild protein.
The main difference between hibernation and torpor is that during torpor, the animal is able to wake up quickly to avoid danger, or if the opportunity exists, exit the den to feed. Waking expends energy and involves violent shaking and muscle contractions, much like shivering. Female bears awaken from torpor to give birth. Hibernating animals, like woodchucks, appear lifeless and are not easily awakened.