Forest Preserve District of Cook County, Illinois
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Nature Bulletin No. 147   March 20, 1948
Forest Preserve District of Cook County
William N. Erickson, President
Roberts Mann, Supt of Conservation

Flying squirrels only glide. Bats are the only fur bearing animals that truly fly, and they've been doing it for at least 50 million years Twisting, looping and zig-zagging through the air, at dusk and dawn, they catch flying insects more skillfully than the swallow or the chimney swift. Each twist and turn means another insect caught, A bat can consume one-half its weight in insects in a single twilight.

Harmful? No, We have one in Trailside Museum that likes to be handled and fed mealworms. They do not get in women's hair. They do not distribute our kind of bed bugs. They are not blind; even in daytime they see fairly well. But they can fly through timber or the narrow twisting passages of caves in total darkness because they have radar, Bats have large specialized ears, Their squeak is pitched so high that few people can hear it, As they fly they also make a supersonic squeak about 30 times per second and are guided by the echoes bouncing back from obstacles.

There are two general types: the fruit-eating bats, which are much larger and found only in tropical regions -- the "flying foxes" of the Philippines and Malay having a wing-spread as much as five feet -- and the insect-eating bats. Of the latter, there are over 600 species and sub- species, including some that eat small fish, some that eat mice, frogs, birds and other bats, and the blood-sucking vampire In the Chicago region there are probably eight species: some of them are of the cave- dwelling type; some are tree-dwellers. Of the cave-dwellers, the commonest is the Little Brown Bat.

In the summer, this bat is widely distributed, each with its own small feeding territory, roosting in barns, attics, under eaves, in hollow trees, or under the loose bark of trees -- since we have no caves. In winter, most of them hibernate in caves, hanging head-down from the ceilings and walls in clusters of thousands.

Most bats have only one young per year. When born it is one-fourth as large as mamma, and she carries it with her as she flies, until it gets too large and heavy. One of the tree-dwelling bats, a female with four young ones clinging to her, was found stranded on the ground.

An old bat on a bat gets bats in her belfry.

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