November 20, 1998

     Notes on Hibernation

In November we become aware that the numbers and species of animals in the wild have greatly dwindled.  Winter strategies for wild Minnesota animals include migration, hibernation and coping.  Without a strategy, death is the result.

While millions of Minnesota common grackles winter in Arkansas, Louisiana and Mississippi, and as honey bees beat their wings furiously to keep warm in their hives, the gopher escapes winter by hibernating from October to March or April.

Hibernation is a winterless life chosen by reptiles, amplibians, many insects, and some mammals.  During the winter, untold millions of animals hibernate across Minnesota.

The physiology of this "sleep" is amazing.  The animal's pulse slows to a few beats a minute, breathing nearly stops, the blood thickens, the internal temperature drops down close to freezing, the metabolism slows, and the kidneys and digestive systems almost stop functioning.  Hibernating animals can "sleep" through almost any disturbance.  A few are able to wake up if their body temperatures approach freezing, but this seldom happens as many animals hibernate below the front line on land or below the ice under water.