A SPECIES of bat actively jams the sonar of its rivals when foraging for food, scientists have discovered.

The Mexican free-tailed bat emits a specific ultrasonic call that interferes with the echolocation of other bats.

Effectively, the creatures employ a natural version of the electronic countermeasures used in human warfare to upset an enemy's radar, sonar, or weapon-targeting systems.

In field experiments, US scientists observed bats trying to jam each other as they hunted flying insects.

Ultrasonic microphones were used to record the high-pitched sounds emitted by the animals. Bats that were being jammed almost always missed their prey, the researchers found.

Lead scientist Dr Aaron Corcoran, from the University of Maryland, said: "This is the first study to show that bats actively jam the echolocation of other bats, and it increases the number of known functions of bat sounds to three: echolocation, communication, and acoustic interference."

In a second experiment, wild bats were lured into trying to capture moths suspended from a fishing line.