Grizzlies are a type of brown bear. They got their name because of the light tips on their fur, which makes them look grizzled, meaning “sprinkled or streaked with gray.” Like all brown bears, grizzlies have short, thick limbs, a big, heavily built body, and a large head. Brown bears also have a large hump of muscle on top of their shoulders, and grizzly bears have the most distinctive hump of all. Their great front claws make them powerful diggers, and they may build a shallow bed on the ground made of leaf litter. In cold climates, grizzlies experience “winter sleep”—unlike true hibernation, the bears' body temperature does not drop drastically. However, the heart rate slows from 70 beats per minute to only 10 beats per minute!