Steve Rhinehart, age 11, of Williamsport, Pennsylvania, for his question:
Do bats hide in the winter?
Steve is interested in the bats that live in his friend's back yard. They are there this summer and they were there last summer. But during the winter season they were nowhere to be seen. Neither, you will notice, was their favorite food. On summer evenings, no doubt you watched them swerving and scooping where the air swarms with gnats and various other warm weather insects.
Most of our various bat species are meat eaters who feed on insects, caught on the wing. These insects tend to be frail creatures who cannot survive the winter's cold. Come fall, the winged adults all perish. The next generation survives until next spring in either the egg, or the pupa stage. This leaves our furry brown bats without groceries. They cannot be expected to survive through months of winter fasting. Nor can they copy the insects and get through the worst of it as dormant eggs or pupas.
The ones we see on a summer evening are usually little brown bats or big brown bats. Sometimes a few that live in Northern states migrate a few miles southward where the,winfer climate is milder. But most of them make arrangements to hibernate until spring returns with food supplies and comfortably warm weather. The little brown bat is a mousy creature, about three or four inches long. As a rule, he lives a sociable life with a group of friends and relatives. The big brown bat is really not much bigger, but his color is a lighter cinnamon brown. Ire tends to live a more lonely life.
Come fall, almost all our big and little brown bats are very busy, hunting extra food to gain a little surplus fat. They also are busy selecting suitable shelters where they can hibernate undisturbed. The little brown bats usually decide to sleep through the long winter where they dozed through the summer days. This may be a dark secret cave or the dim rafters in the roof of a farmer's barn.
During the summer, the big brown bat likes to change his daytime sleeping quarters. Yesterday maybe he settled for a corner under the eaves of a roof or behind a window shutter. Next week he may select a secret pocket in a tree trunk or perhaps a quiet cranny in some rocks. Come fall, he hunts around until he finds a similar place to shelter him through his winter hibernation.
Bats, of course, are warm blooded mammals, and though they regulate their body temperature better than most, none of them can abide the cold. This is another reason why the insect eating species must arrange to avoid the worst of the winter. Most,but not all, of the common bats that live near our houses and back yards hibernate fairly close to home base. But the common red bat and others who live in trees and shrubbery are likely to migrate to warmer winter quarters. They flock South in the fall and back home again in the spring, flying mostly at night and on gloomy days.