Neal Cannon, age 11, of Marion, N.C., for his question:
Can a bat see?
The little brown bat does not seem to be blind. He has a pair of bright dark eyes and he flies around without bumping into obstacles. In fact, thousands of bats can mill around at high speed in a darkened cave without once having a collision. A little bat can fly around and around in a room without colliding with the walls or furniture, even in the dark.
It would seem that a bat has very good eye sight. Ho knows whore ho is going and can maneuver at high speed even in a dim light. Perhaps like the owl and the pussycat he can see in the semidarkness. Then ‑why do we say that someone is blind as a bat, meaning he stumbles because he cannot see very well?
The truth of the matter is that the furry little bat does not have very good eyesight ‑ though he is far from blind. He rarely, if ever, comes out in the dazzling daytime sun. For he gets around best in the dim light of evening. At twilight, he sees as well as you do. At high noon, however, you see bettor than he does.
The little bat does not depend very much on eyesight to get around. He uses an amazing trick to prevent collisions in the air. It is a sonar device, somewhat like radar. His remote ancestors worn using sonar long before our ancestors learned to read and write. The trick is done with echoes and to do it a bat needs a voice and a pair of very sensitive ears.
A bat in a cage chirrups as he flies around. Actually we hear only the lower sounds of his cheerful chirrup. With each cry, his voice rises way up into the supersonic heights, too high for the human oar to hear. Our ears can hear high noises up to about 20,000 vibrations a second. The supersonic high notes of a bats voice run to about 50,000 vibrations a second.
The bat's supersonic voice bounces from solid objects around him. His ears receive echoes which tell him how far away those objects are. His wing musclos respond in a split second and he veers this way and that to avoid traffic accidents.
Somehow the clover bat know his own voice from the voices of his friends and relatives. For often thousands of bats fly together in a dimly lit cave all of them operating their sonar equipment. Yet each once obeys only his own echoes, for there is never a collision.
Most bats doze through the day, hanging upside down in a cave or some dark corner. They come out to food nt sundown when the air is cloudy with midges and mosquitoes. The furry bats fly with their mouths open, trawling for insects. Their bright eyes can see, but not well enough to avoid obstacles or to hunt enough tiny insects for supper.