Bats needs to be good listeners to detect prey crawling through vegetation. And in these circumstances, the familiar technique of "echolocation" lets them down.This is the conclusion of a study by a Bristol University researcher, reported in Nature today. The study shows that bats are very good at capturing noisy live prey from leaf litter, and both dead or live prey in uncluttered habitats, but find it difficult to capture dead prey from clutter on the ground.
Bats that capture animal prey from the ground often emit characteristic short-duration broadband frequency-modulated (FM) echolocation calls. These calls are well suited to locating flying prey, but are less effective for finding prey on cluttered surfaces because echoes reflecting from the ground mask prey-generated sounds.
The researchers used mouse-eared bats for the study and recreated four artificial microhabitats, each mimicking foraging conditions faced by bats in nature. The ability of the bats to detect and capture live and dead prey was measured under each condition.
Dr. Gareth Jones, Reader in Biological Sciences at the University of Bristol, said, "These findings contradict the view that the echoes from FM calls can provide detailed information about objects to allow bats to distinguish prey from cluttered surroundings."
The research team includes scientists from the universities of Bern, Lausanne and Aberdeen.
(Reference: Effect of acoustic clutter on prey detection by bats by Raphael Arlettaz, Gareth Jones, Paul A. Racey. Nature, 13 December 2001.)
[Contact: Joanne Fryer]
14-Dec-2001
