Our local bats are well known for their ability to “see” with sound using a navigational system called echolocation, or sonar. Along with other special physical features, sonar allows bats to hunt for small flying insects at night.

Echolocation is similar to an “echo canyon”: if a person stands on the edge of a canyon and shouts a word, she will hear it come back to her. Bats produce ultrasonic, high frequency sounds using their voice box or by clicking their tongues, then listen to the echoes that return. Bats can determine the location and size of an insect, as well as the direction the insect is moving, all by echolocation. They use this adaptation along with vision, not instead of it.

The sounds bats emit are well beyond the normal range of human hearing, but they can be detected using a special device. Bat detectors pick up the high-frequency sounds and convert them to frequencies audible to humans. The detectors can also help pick up subtle differences in the bats’ sounds, which can indicate different species or communication among bats of a given species. Forest Preserves staff use bat detectors to find and identify different species of bats throughout the county.