Mexican free-tailed bats use echolocation to "jam" signals from competing animals, during nightly hunts for food.
Bats can face up to one million other bats, as massive flocks of the flying mammals cruise the skies in search of insects. As the creatures fly around in the darkness, they utilize echolocation - a natural form of sonar - to locate flying morsels.
Tiger moths and some other insects create unique sounds that could save them when they are in danger of becoming a meal for a hungry bat. Clicking sounds created by the insect are able to interfere with the echolocation system of the predator, occasionally causing the bat to miss.
Bats also use similar techniques, according to a new study, jamming signals given off by members of its flock. The battle of sounds continues until one of the animals gives up, leaving the contest for the target.
Researchers eliminated other possibilities for unusual sounds heard from bats, including the possibility the animals were communicating with each other.
"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," Aaron Corcoran of the University of Maryland said.
Corcoran traveled to the border between New Mexico and Arizona in order to study how tiger moths jam the sonar of big brown bats. While there, he observed Mexican free-tailed bats circling above the group, making unusual sounds. Analysis carried out later on the recordings revealed sounds created by Mexican free-tailed bats were similar to those of the tiger moth.
The Southwestern Research Station in Arizona was used as a base of research, along with a parking lot at a high school in Animas, New Mexico. Investigators assembled a series of cameras and ultrasonic microphones to track the animals as they hunted. They found bats nearly always missed targets when another bat was jamming their ultrasonic sonar signals.
Artificial jamming signals were created by researchers, and played to wild bats, as they hunted moths suspended from fishing line. The flying mammals in this experiment only missed they prey when jamming signals were played at specific wavelengths and times.
Tadarida brasiliensis, as the Mexican free-tailed bat is scientifically known, is a highly-social animal, although they are solitary hunters. The animals possess at least 15 distinct calls, which they produce throughout the night.
Jamming of signals in the fight for prey has not been witnessed within other species, apart from Mexican free-tailed bats. It is possible that other species that employ echolocation, such as dolphins, could also benefit from the practice.
Echolocation jamming by bats was profiled in the journal Science.