Every Autumn, most species of bears worldwide are placed in their dens and hibernate during the cold Winter months.
This period of hibernation usually lasts about 6 months. And during that time some species of bears, such as the black bear (Ursus americanus), may reduce his beating heart from 55 beats per minute to only 9, thus decreasing the rate of metabolism up to 53%.
During hibernation, bears may have no need for defecation or disposal of feces from the body.
How is that possible?
To understand what happens in the body when the bear hibernates, we must first understand what exactly constitutes hibernation and why it is considered that bears do not hibernate for real.
Basically, under hibernation it means that an animal goes into a state of complete inactivity. During that time blood flow and metabolic rate decline to levels that seem impossible for species that do not hibernate.
Some species, such as Arctic squirrels are known for their true hibernation as they reduce their body temperature below freezing.
Bears retain their body temperature at a high level which allows them to keep their cubs safe and stay prepared for the dangers that may lurk beyond the comfortable den.
According to some researchers, this means that bears do not hibernate. While others say this is a super hibernation because, to be realistic, the ability to be aware of their surroundings and retain body heat without eating, moving or drop their feces is really incredible.
Long ago, when researchers first studied how bears hibernate, often found mass of unidentified material in their intestines.
But they assumed that it was plants, fibers of the bear and other things that are difficult to digest.
It was thought that the strange diet of bears facilitated a way to “wash away” the digestive tract and create a “rectal plug” which literally blocked new feces until spring.
But recent research has found that the bears do not eat special food to create this fecal stopper. Rather, excrete in the intestinal cells continue during hibernation and create feces even when the bear does not eat anything.
“During those five to seven months spent in their dens, feces accumulate in the lower intestine and form a stopper. The stopper is from 3.8 to 6.4 cm. in diameter.”
“Fecal stopper is simply feces which remained in the intestine. As long as the walls of the intestine absorb fluids, they remain firm and dry”. Explains North American Bear Center on its website.
Based on video footage from the dens of bears, researchers have shown that the reason they often find plants and fiber in the feces is that bears spend a long time cleaning.