The Brown Bear (Ursus arctos) varies in size and color. Some types of the species have close to blonde fur while others’ is almost black. Brown bears in North America are known as grizzly bears because of the white and tan tips they have on their fur. Grizzly actually means "sprinkled or streaked with gray." There are several brown bear subspecies found on other continents, but they are often smaller than their North American relatives.
These bears are known for their sleeping habits. They spend four to six months each year hibernating in a den, which equates to about one-third or half of their lifetime. During this time, their body temperature doesn’t drop drastically, but their heart rate slows down significantly from about 70 beats per minute to about 10. This allows for their metabolism to slow down and keeps them alive during the winter when there is little food available to them. All winter long, bears live off of the fat they’ve stored in the spring and summer. Because of this, they lose about one-third of their body weight during hibernation. Their climate directly correlates with how long they spend hibernating. If they live in warmer climates, they’ll spend a lot less time in their den.
Cubs are usually born during hibernation in January or February. While the mother stays asleep, the cubs nestle up against her to stay warm and to get milk. By the time spring comes, they are able to follow her outside.
Fun Brown Bear Facts
- Bears are the only animals that do not go to the bathroom the entire time that they hibernate. Scientists have been able to research the way bears recycle urine, which has helped human patients with kidney failure.
- Bears can run up to 30 miles per hour despite their heavy build.
San Diego Zoo
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