Imagine being able to hear an insect’s footsteps! Such amazing hearing belongs to the world’s only flying mammal​—the bat. Of course, bats require specialized hearing to navigate in the dark and to catch insects by means of echolocation, or sonar.e Says Professor Hughes: “Imagine a sonar system more sophisticated than that found in our most advanced submarines. Now imagine that system is used by a small bat that easily fits in the palm of your hand. All the computations that permit the bat to identify the distance, the speed, and even the particular species of insect target are performed by a brain that is smaller than your thumbnail!”

Because precise echolocation also depends on the quality of the sound signal emitted, bats have the “ability to control the pitch of their voice in ways that would be the envy of any opera singer,” says one reference.f Apparently by means of the flaps of skin on the noses of some species, bats can also focus sound into a beam. All these assets contribute to a sonar so sophisticated that it can produce an “acoustic image” of objects as fine as a human hair!

[Box/Pictures on page 9]

Insects Beware!

“Each day, just around dusk, a truly astonishing event takes place under the rolling hills near San Antonio, Texas [U.S.A.],” says the book Sensory Exotica​—A World Beyond Human Experience. “At a distance, you might think you saw an enormous black cloud billowing from the depths of the earth. However, it’s not a cloud of smoke that darkens the early evening sky, but the mass exodus of 20 million Mexican free-tailed bats from the depths of Bracken Cave.”

A more recent estimate places the number of bats exiting Bracken Cave at 60 million. Climbing up to 10,000 feet [3,000 m] into the night sky, they pursue their favorite meal, insects. Although the night sky must contain an overabundance of ultrasonic bat calls, there is no confusion, for each of these unique mammals is equipped with a highly sophisticated system for detecting its own echoes.