Egyptian fruit bat their days roosting in trees or caves, often with large groups of other bats, sometimes numbering in the thousands. They emerge from the roost to forage for food in the late evening, and return just before dawn. They hang upside down, with their wings folded closely around their bodies. Egyptian fruit bats, along with other species in the genus "Rousettus", are the only megachiropterid bats to use echolocation, which they accomplish by emitting a series of sharp clicks with their tongues. The clicks are normally slow and constant, but these clicks speed up dramatically when the bats approach an object.
Robert Galambos generate and hear sounds an octave higher than can be heard by humans and other animals. Experiments they conducted used methods developed by Hallowell Davis to monitor the brains of bats and their hearing responses as they navigated their way past wires suspended from a laboratory ceiling. They showed how bats used echolocation to accurately avoid obstacles, which they were unable to do if their mouths or ears were kept shut. Griffin coined the term "echolocation" in 1944 to describe the phenomenon, which many physiologists of the day could not believe was possible. Using electrodes implanted in the brains of