Reginald Alderman, age 11, of Charlotte, North Carolina, for his question:
Do bears hibernate or sleep through the winter?
We hear a lot about hibernating bears, also about how they get ready and emerge from their long winter sleep. Then we pay a Christmas visit to the zoo and, to and behold, there are the bears as usual, hoping for handouts. The truth is that right now, most wild bears are dozing in their dens. But bears in captivity remain active all through the winter.
Hibernation is much deeper than ordinary sleep and somewhat like an unconsciousness. If you poke a hibernating woodchuck, he won't move a muscle. He won't stir if you take his temperature and check his pulse. This medical check up reveals that his heartbeat and temperature are way below normal. This is true hibernation.
A bear who lives in the wilds is not a true hibernator and though he sleeps soundly through the winter, disturbances arouse him. If you tried to check his pulse and temperature, he would open an eye, utter a grumpy growl and most likely take a swipe at you. Actually his pulse, temperature and other body processes are only slightly below normal.
Both the bear and the woodchuck eat extra food in the fall and do not eat or drink anything during the winter rest period. Naturally their bodies consume food, even though their life processes are slower. They consume the layers of fat stored away during the fall feasting. The hibernating woodchuck can fast longer than the sleeping bear, who is quite skinny when spring returns.
When winter snows blanket his world and hide what's left of his food supplies, the fat bear shuffles off to find himself a winter den. He prefers a small cave or a hollow tree, just big enough to hold one bulky bear. There he falls asleep for days and perhaps weeks.
Later, perhaps his roof leaks or heavy snows may tumble through his door. This sort of discomfort arouses him and chances are he shuffles off to find himself a more dependable bedroom. Several times during the winter a bear may wake up and go outside to the toilet.
Come spring, after his long winter fast, you would expect a famished bear to come forth in a grumpy mood. But observers report that this is not so. He saunters around in what seems like a rather gentle mood, enjoying the new spring season. Now and then he nibbles a tender green shoot and sips a little water. He does not take a large meal for some time. After all his tummy has been out of work for several months and no doubt needs time to adjust to its daily duties.
The female wild bear has a more interesting sleep period. Her helpless little cubs are born in mid winter, when the blizzards rage outdoors. For several weeks their whole world is a dark cozy den, with a big furry mother bear to warm them and cuddle them and feed them. Come spring, dressed in their bear fur coats, the wide eyed cubs are eager to tumble outdoors and explore a world full of miracles.