Although bears are associated with hibernation, they do not truly hibernate. It is more accurate to say that they experience a winter lethargy or torpor. Though their metabolisms slow down by 50-60 percent, they easily wake up, especially female bears, who give birth to between one and three cubs during torpor. This adaptation enables bears to survive frigid temperatures and insufficient food supplies. During autumn, bears in northern climates increase their body weight by 35 percent in preparation for winter, when they rely on body fat to survive. Bears in Alaska may go into torpor for six months, while bears in Southern California, because they have access to a steady supply of food year-round, do not go into torpor at all. Black bears’ sense of smell is among the best in the animal kingdom and seven times stronger than a dog’s. Some experts report that bears have detected an animal carcass from up to 20 miles away. With short, curved claws, black bears are adept tree climbers. They are also good swimmers and sometimes find their way into backyard swimming pools in foothill communities around Los Angeles. They can run more than 30 mph for short distances. While black bears are generally not aggressive, they should never be underestimated. Females are very protective of their cubs, who remain with their mothers for about two years.
American black bears are found in forests throughout North America, including the United States, Canada, and Mexico.
Black bears are opportunistic omnivores, with 75 percent of their diet comprised of plant material including nuts, berries, grasses, and roots. The balance is insects, carrion, fish, deer, and other mammals. They are fond of honey.
Although their fur is often black, American black bears can also be brown, cinnamon, blond, silver-blue, or even white. Both the spirit, or Kermode, bears of British Columbia, Canada, and the silver-blue glacier bears of Southeast Alaska are black bears with white fur. Adults reach a length of four to seven feet and weigh between 150 and 600 pounds. Females weigh 25 percent less than males.