A bat finds its way around with sound rather than sight. Using a sensory process called echolocation, the bat emits ultrasonic pulses that hit objects like leaves, trees, and insects, and bounce back to the bat to tell it what's in the vicinity. When an echo returns from "clutter" at the same time a sound bounces back from an insect, the bat has a real challenge figuring out where the bug is.
In an article published in the open access journal PLoS Biology, University of Maryland psychology professor Cynthia Moss reports on new research that shows bats have methods for echolocating food in "clutter" that may be more complex than scientists have thought.
In its hunt for prey, a bat flies around at high speeds, emitting pulses of varying pitches and speeds. Using an array of high-speed infrared cameras and strategically placed microphones in the "Batlab," Moss's team was able to match slowed video and audio recordings of the bat's echolocation activity and corresponding movement as it pursued an insect tethered to a string. The insect could be out in the open, or nestled in among leaves.
"We have found that bats adjust the timing of their sounds when they encounter clutter, and they seem to 'strobe' the world with sound," says Moss. As the bat gets closer to what could be an insect, it sends out an array of quick repetitive pulses, called sonar strobe groups. Finally, when it has locked onto the bug, right before scooping it up, the bat shoots a rapid fire series of sounds called the final buzz.
"In each case we found that the bats spent more time strobing when the insect was positioned near a plant, a strong indicatio
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Contact: Paul Ocampo
press@plos.org
415-624-1224
Public Library of Science
6-Mar-2006