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The word 'hibernate' comes from a Latin word which means
'winter sleep'. Not all animals in temperate countries
hibernate. Some, like the bear, the squirrel and the
chipmunk do not really hibernate. They do sleep more
during the snowing season than in summer but on warm and
pleasant days, they will wake up and come out in the
open. A good example of a typical hibernating animal
is the woodchuck. Unlike the squirrel , it does not have
to work extra hard during the summer months to collect
and store food for the cold season. It depends on plant
food and when the season comes along, its food supply is
gone. However, it has a reserve supply of fat on its own
body. Thus, when it can no longer find food, it crawls
deep into its burrow and goes to sleep. It sleeps
through the whole season and lives on the fat which it
has stored in its body.
The sleep of a true hibernator is almost like death.
It is quite different from ordinary sleep. While an
animal is hibernating, all its body functions almost
stop. The temperature of its body decreases rapidly
until it is only slightly higher than the surrounding
air in its den. This allows the animal to burn
the fat in its body very, very slowly. Since it burns
less fuel, less oxygen is released and the result is
that its breathing is slower and its heart beats only
faintly. If the temperature in the den becomes very low,
the hibernating animal wakes up, digs itself a little
deeper and goes to sleep once again.
The animal is awakened in spring by the change in
temperature, moisture and hunger. It then crawls out of
its den.
It is interesting to know that many cold-blooded
animals hibernate too. Earthworms crawl down into the
earth below the frost line; frogs bury themselves in the
mud at the bottom of ponds and snakes crawl into cracks
in the rocks or holes in the ground. |
