Chris Sargente, age 12, of Staten Island, New York, for his question:

Why is it necessary for bears to hibernate?

Chris reasons that a bear's shaggy overcoat should be able to keep him warm through the winter. It certainly is    and some bears do indeed stay up and around through the cold season, without shivering or sneezing. Hence, it is logical to search for another reason for winter hibernation. The answer is groceries    just what you would expect from this born moocher.

A bear's assortment of teeth enables him to dine on both meat and vegetables and his digestive system is adjusted to cope with a mixed diet. You would expect such a large animal to plan at least one large meal for himself every day. Sometimes he does indulge in an enormous banquet. But he is by nature a snacker, very fond of sampling a wide variety of this and that, in small helpings.

This sort of gourmet tasting keeps him busy throughout the day. To satisfy his choosey appetite, he wanders over a wide range, never missing a chance to track home a wild bee and indul7e his sweet tooth faith a feast of honey. During the spring, summer and fall his world is a free supermarket, teeming with samples of his favorite groceries. Chipmunks and small furry creatures scuttle among the stones, wild black¬berries and blueberries hang temptingly on the bushes, a few birds lay tasty eggs in nests on the ground. In spring, tantalizing salmon swim in the streams.

However, this sort of gourmet living comes to an end in the late fall. Before his supermarket closes for the season, the bear takes advantage of the late berry season and gains enough fatty poundage to last him, for several months. After all, he is not the type of character to make do with meager pickings. Besides, he would just as soon not have to cope with frosty snows and chilly toes.

So he shuffles off to find a cozy corner, perhaps in a smallish cave or hollow tree. There he gets comfortable and goes to sleep. Actually he does not sink into the deep coma of hibernation. Once in a while he wakes up to go to the bathroom. Sometimes he fails to tuck himself back in bed and a blizzard may pile a blanket of snow on his sleeping back. The female bear gives birth in mid winter. You can bet your boots this devoted mother does not sink into a deep sleep when her precious cub needs her tender, loving care.

So much for the hibernation of a bear in the wild. However, these born moochers know that his human aquaintances can provide him with his favorite snacks    summer and winter. This may explain why bears that live in zoos seldom take a long, winter sleep, even in extremely cold climates. Apparently, if food is plentiful, a bear's coat makes the worst of the winter bearable.