Jeannie Behr, age 12, ofAlbany, N.Y., for her question:

DO SNAKES HIBERNATE ALL WINTER?

Now and then, somebody reports seeing a snake crawling around in midwinter. This is unusual, but it may happen when the frosty weather gives way to a mild spell. Even a lazy woodchuck may wake up for a short while in the middle of winter. However, most snakes and other hibernators usually doze off in the fall and remain in a deep deep sleep until the first breath of spring.

The snakes are cold blooded animals, which means that they absorb most of their necessary body heat from their surroundings. This is fine when the weather is warm and where winters are mild enough to stay well above freezing. But when things become chilly, a snake's body processes slow down and he becomes sluggish. He feels too tired to hunt and escape from his enemies. What's more, cold weather brings a shortage of frogs and other favorite food.    

This explains why he must hibernate until things improve. As the fall nights grow chilly, the average snake seeks a cosy den where he can rest undisturbed through the winter. Usually he curls around in a tight coil with his head in the middle. He may occupy a small crevice in the rocks or in the roots of a tree  all by himself.

Or he may share a larger den with two or three or several dozen other snakes. There is evidence that he leaves a scent on his trail and other snakes follow it to the community hideaway. Sometimes the winter den is shared with turtles and other winter sleepers.

The woodchuck and most hibernators survive on their stores of fat. But the snake is not bothered by lack of food or water. After a heavy meal he is used to a long fast, often through several months. His skin keeps in moisture and normally he needs very little water. His heart and breathing slow down to almost nothing and if you poke him with a stick he does not move a muscle.

However, sometimes a warm spell arrives in the middle of winter. And the hibernating snake mistakes it for spring. He wakes up and crawls around for a while. But when the weather turns chilly again he sees his mistake ¬and returns to finish his winter sleep.

Some people claim that poisonous snakes are harmless during hibernation. But let's not take any chances. A rattler's bite is dangerous, even when he is only half awake. And some experts claim that he is especially bad tempered when he has been fooled by a mild spell in the middle of winter.