A bat approaches a tethered moth during the experiment. (Courtesy of Nickolay Hristov)

Some tiger moths can produce sounds that interfere with a bat's sonar, rendering the predator unable to find its prey, a study has found.

Researchers had previously known that tiger moths made ultrasonic clicking noises, but weren't sure why, said the study published Friday in Science.

There were three main possibilities — that the noises were intended to:

• Warn bats that the moths weren't tasty.
• Startle bats.
• Interfere with the bats' ability to find them using echolocation.

In order to figure out which was true, biologists Aaron Corcoran and William Conner of Wake Forest University in Salem, N.C., and Jesse Barber of Colorado State University in Fort Collins, Colo., put a bat in a room with either a normal tiger moth of the species Bertholdia trigona and or a moth that had had its noise-making organs removed.

Researchers were previously unsure why moths of the species Bertholdia trigona made ultrasonic clicking noises. (Courtesy of William Conner)

The researchers then observed the bat using high-speed infrared cameras and microphones.

Bats locate their insect prey in the dark by making their own ultrasonic noises, listening for the echo, and using that to figure out how far away their prey is — similar to the way boats use sonar.

The researchers found that a bat was at least four times more successful at catching a moth that had its noise-making organs removed than one that could make noises. They also found that most of the bats liked to eat the moths and did not stop trying to attack them after repeated attempts, suggesting that the moths' clicks were not used as a warning.

The bats' ability to catch the noise-making moths did not improve over time, as they would be expected to if the bats were initially startled by the noise, but eventually got used to it.