December 15, 2008
These whispering bats never really whispered. Their echolocations were thought to be about 70 decibels, about the level of sound coming from regular speaking. But when two scientists measured the calls from a couple of species—the Jamaican fruit bat (Artibeus jamaicensis) and the long-legged bat (Macrophyllum macrophyllym)—in Panama, they were a bit surprised to find out how inappropriate the name really was.
They report in the Journal of Experimental Biology that the long-legged bat reached a top volume of 105 decibels (louder than the subway in New York) and the Jamaican fruit bat topped out at 110 decibels (front row of a rock concert). Because the decibel scale is logarithmic, that means the fruit bat was about twice as loud is its long-legged cousin.
The scientists attribute the difference in noise level to the difference in lifestyle. The Jamaican fruit bat has to search over a large area to find fruiting trees. Loud, long-carrying shrieks would help the bat orient itself in its forest home. (Bats use echolocation for finding their way and finding their prey.) The long-legged bat, though, scoops up insects from the water with its tail, and may not require such a wide-ranging call.
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