Jens Kuehl, age 13, of Spokane, Wash., for his question:
DOES A POLAR BEAR HIBERNATE?
Polar bears are expert divers and swimmers. They use their front legs for swimming, tailing their hindlegs. Under the skin is a heavy layer of fat which is up to three inches thick on the haunches. This extra fat helps keep the polar bears buoyant. They can swim more than 200 miles from land, usually keeping their heads stretched forward as they move at six miles per hour.
Polar bears live on or near the islands of the Arctic Ocean, although they spend some of their time on the arctic shores of Canada, Alaska, Greenland and Siberia.They have also been seen in the Atlantic ocean as far south as the Gulf of St. Lawrence.
A male polar bear averages seven to eight feet in length with some going up to nine or ten feet. The average weight is about 900 pounds, going up to 1,600 pounds. The female is a bit smaller: she only weighs about 700 pounds. Both males and females have thick, yellowish white coats of fur.
It has often been said that cubs are born while the mother polar bear is hibernating. This is not true. Polar bears, like other bears, do not hibernate in the strict sense and it is now usual to refer to their sleep as winter dormancy.
A female will have a gestation of 240 days, usually delivering two cubs in December or January after mating in April or May. Each baby will be about a foot long at birth and weigh less than two pounds. The eyes will open at 33 days and the ears at 26 days although hearing is imperfect until the cub is 69 days old.
A pregnant she bear seeks out a bank of snow in the ice of a hill and digs into it before she starts her winter dormancy. The cubs don't start to walk until they are about 45 days old and are not weaned for three months. The babies will stay with the mother until they are at least 10 months old. Sometimes they stay until they are almost two years old.
When a she bear is ready to mate again, she will drive away any cubs that may still be remaining. By this time the youngsters will probably weigh between 200 and 400 pounds.
Favorite food of the polar bear is seals, especially the ringed seal. They also eat fish and sea birds. Usually in the late spring or early summer they will eat large amounts of grass, lichens, seaweed, moss and other plants.
Male polar bears also go into periods of winter dormancy. They remain inactive for a much shorter period of time than the females, however.
A walrus may occasionally gore a polar bear in self defense, but generally speaking, the huge white arctic resident has no enemies other than man.
In 1973, Canada, the United States and Russia signed an agreement prohibiting most commercial and recreational bear hunting.