Hibernating mammals such as black and brown bears, the brown bats, marmots, woodchucks, arctic ground squirrels survive the cold winter by lowering their body temperatures and snoozing away the frigid time in Alaska, say Elizabeth Manning in her online article “The Long Sleep: Which animals hibernate.
Each have their own method of conserving energy when food is scarce. Contrary to what one usually thinks about the long sleeping habits of the largest mammal, the black or brown bear, they are the lightest sleepers. They do not pass out into an unconscious state as do some other hibernating mammals but instead they tone their activity down considerably.
They reduce their body temperature only slightly, maybe dropping it about ten degrees but their heart rate and their breathing is lowered. They are aware of their surroundings and if provoked have been known to attack. They must remain aware since this is the time they give birth to their young. They must remain alert for this activity and to care and to feed the family.
The most amazing feat about the bears well publicized quiet time is their ability to live, maintain a body temperature that is only slightly lowered without even have to eat, drink, or even eliminate their waste. How can this be you ask? They recycle their waste. Their bodies were constructed in this way. About six months out of the year they are in this semi-retired state. When spring approaches they emerge from their underground dens somewhat emaciated and no doubt hungry. They begin their search for food at about the time it is beginning to be available to them. They are famished as during the long winter months they have used up all their stored fat. Around the middle of April the Black bear opens his door and ambles out, and in a week or two the brown bear emerges.
There is much going on in the bears den than is known by his human inspectors. Who exactly has been privileged to have invited in as a guest to observe the going on? Yet cautiously the work goes on about finding out more about the sleeping habits of mammals who were born with the necessity of preserving themselves through the conservation of energy.
The lowest known temperature of hibernation is that of the arctic ground squirrel who sleeps about three feet under a blanket of snow and hardened sod. They can survive a temperature as low as 27 degrees Fahrenheit. Mammals, unlike the other hibernating creatures that react to the outside temperature such as the frogs, snakes and other cold-blooded animals, can go dormant, or semi-dormant – as with bears – while keeping a warmer inside temperature.
This phenomenon is one of the miraculous ways nature has of answering all the problems of survival for its creatures. The world is frozen over and the food supply is scarce or non-existent and therefore it becomes necessary for certain animals to either eat a lot to last during the long winter such as bears and woodchucks do; or as squirrels do and gather nuts. The hibernating bats may find the insects they gorge on in warmer weather are also going through hibernations and are scare. They hang themselves up side down in a hollow place in a tree or in some old house and simply wait until the weather changes.