Bear hibernation: what happens to the animal during prolonged sleep?


Hibernation is one of the most interesting survival tools for mammals. Unlike suspended animation, when a cold-blooded creature literally freezes through and through, the body temperature of bears remains high, and the animal easily wakes up in case of danger.

What happens to a bear during hibernation? Where do his waste products go during sleep? Do bears really give birth in winter? How did predators develop such a wintering mechanism?

3/4 brown bear diet


During deep sleep, the bear’s body lowers its pulse to 9 beats per minute. The metabolic rate drops by 53%. The main consumer of energy in the body of any animal is the muscles and the brain. The digestive and cardiovascular systems are slightly less energy-consuming.

However, the muscles and brain are inactive at the time of sleep, and the work of the digestive and cardiac systems is significantly slowed down. Cells and organs consume energy only to maintain their existence.

This energy is taken from subcutaneous fat and glycogen, which accumulates during the active period of life — from mid-March to early November. During the winter, the predator loses up to 80 kg of weight. The animal receives water by splitting fat, like camels and other desert inhabitants. Thus, the bear lives for several months until it wakes up.

Under normal conditions, starvation and immobility lead to muscle atrophy. However, bears lie motionless in dens for 6 months, but retain the entire volume of muscle tissue. How do they do it?

According to biologists from the University of Barcelona, ​​in the plasma of a predator

Scientists hope that in the future, this discovery will allow humanity to treat metabolic diseases and significantly expand the capabilities of our body.

Another amazing feature of the body is that during the period of sleep, the animal does not defecate. This condition saves the creature from losing fluid, which would be impossible to replenish without waking up.

All this leads to the formation of a certain amount of waste. They accumulate in the intestines and become dehydrated. When the bear wakes up, he immediately cleans his intestines in a natural way, often right near the entrance to the den.

Curiously, bears are even capable of giving birth to children during hibernation! When they wake up, they find a number of already rather large and more or less independent cubs. From an evolutionary point of view, such a mechanism allows creatures to preserve offspring during the most vulnerable period of development for them.

Such an unusual lifestyle of bears was triggered by a genetic mutation that occurred more than 200 thousand years ago. Sleep gave such significant advantages in survival that after millennia only such individuals remained on the planet.