Bats can detect rustling sounds of prey despite highway background noise

Washington, Sept 20 : Bats, known for their sharp-hearing, can easily pick up rustling sounds produced by its prey, even against the background noise of a highway, according to a new study.

In their study, Bjorn Siemers from the Max Planck Institute for Ornithology in Germany, and colleagues monitored foraging bats' responses to rustling mealworms in noisy environments and

While working with a group of young male greater mouse-eared bats, the researchers allowed individual bats to forage freely in a large soundproof room.

After dividing the back of the room in two, they provided the bats with a choice of rustling mealworm snacks in each half of the room to dine on.

In the course of many days, the bats divided their attention equally between the two halves of the room, easily locating the rustling nibbles.

In order to see the bats' reaction after switching on a noise in one of the two dining areas, the team synthesized true white noise before playing the sound in one half of the flight arena. But, the bats instantly avoided the unpleasant buzzing sound, spending more than 80 percent of their time hunting in the quiet dining area.

Later, they recorded traffic sounds within 15ºm of a busy local highway and found that the animals were less bothered by the loud traffic noise than they had been by the white noise buzz. But they still preferred hunting in the quiet dining area, only spending 38.7 percent of their time gathering mealworms from the traffic noise booth.

And, when the bats ventured into the noisy dining area, they had no obvious problems locating their rustling prey against the traffic background.

To their astonishment, when the team played a simulation of a high wind rattling reed beds, the bats seemed to find it difficult to locate their prey and preferred foraging away from the sound, even though it was a noise that they encounter naturally in their day-to-day activities.

The researchers concluded that man-made noise does interfere with bat foraging, but less than a very high wind rattling through vegetation.

However, Siemers still does not know how man-made noise interferes with foraging bats as they listen out for a rustling lunch, but it probably does discourage these animals from foraging close to busy road networks.

The results were published in The Journal of Experimental Biology.

ANI