To elude bats, tiger moths jam sonar
— Photo: G. Karthikeyan
Foiling tactic: The bats, startled by the ultrasonic clicks made by the moths, allow them time to escape.
In the continuing battle between bats and tiger moths, score one for the tiger moths.
A study shows that one moth species uses a different kind of defensive technique to avoid becoming bat fodder.
Many bats use echolocation — a type of sonar using ultrasonic pulses — to find prey. Tiger moths produce ultrasonic clicks of their own, and earlier studies showed that the sounds have two functions. For some moths that are toxic to bats, the clicks warn the bats to stay away.
Time to escape
For others, the clicks startle the bats, allowing the moths time to escape. Aaron J. Corcoran and William E. Conner of Wake Forest University, and Jesse R. Barber of Colorado State University, have shown that for the Bertholdia trigona species, the clicks serve a third function. They keep big brown bats, which would normally dine on B. trigona, at bay by jamming their sonar.
The researchers set up experiments that eliminated other possible functions. For example, if the clicks served to warn the bats that the moths were toxic, the bats would be expected to capture a few insects before learning to avoid them.
Startle effect
That did not happen, though. If there was a startle effect, it would wear off as the bat got used to the sounds. But the researchers found that the moths’ ultrasonic clicks worked over a long term.
Audio recordings showed that the moth clicks disrupted the bats’ cycle of echolocation calls, which increase as the bat nears its target.
This, the researchers say, suggests the bats were still trying to capture the prey but were confused by the moth’s ultrasonic clicks. — © 2009 The New York Times News Service
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