Noise may disrupt a bat’s dinner

BOULDER, Colo. — The roar of humankind’s machines may make it hard for some bats to hear the tiny footsteps of their prey.

Bats that snatch insects off leaves and other surfaces find their targets by listening for the little rustles and scratchings of prey in motion. In the lab, pallid bats (Antrozous pallidus) took extra time to locate live insects when speakers blared noise, Jessie Bunkley of Boise State University in Idaho reported July 30 at the annual meeting of the Animal Behavior Society.

For the test, Bunkley released bats into a darkened chamber with an array of bowls. One held live mealworms, and the others offered freeze-dried mealworms, dead and silent. With no extra noise, pallid bats averaged 3.5 seconds to locate the living mealworms.

But when Bunkley played recordings of highway traffic or the noisy compressors found at gas wells, bats took 6 to 8 seconds to locate their meals. Bats operate on a strict energy budget, so small delays for each food item could add up to nutritional stress, Bunkley said.

To see what happens in the real world, Bunkley now monitors bats at 50 gas wells, half that have loud compressors and the other half without.