Bats jam each other's sonar in food competition

Echolocation allows bats to find and capture insects in complete darkness, but it also alerts nearby competitors of a bat's presence. Eavesdroppers find food by listening in on another bat's hunting cries, increasing competition for insect prey. In a paper published in Science (download article here), we showed that Mexican free-tailed bats take this one step further; they jam a competitor bat's echolocation to prevent them from capturing insects. This is the first time echolocating animals have been found to jam each others echolocation

Mexican free-tailed bats are highly gregarious and social animals. Up to a million bats live together in caves in the American Southwest. Bats fly 100 km (62 miles) or more each night to get their fill of insects. Because of these conditions, competition for prey is fierce. These bats appear to have responded by evolving the unique competitive strategy of jamming each other's echolocation.

So how does it work? When a bat attacks an insect it makes a specialized series of echolocation calls that help it find the prey. This is called a feeding buzz. When another bat hears a feeding buzz it emits a specialized jamming call that prevents the hunting bat from properly hearing the echoes returning from the prey. Its like when you can't hear the person next to  you talking at a party because the obnoxious guy at the other table is talking so loud. Except here the bats are making a call specially designed to disrupt you from hearing the words properly. Because the bat can't get the information it needs from the echoes, i.e., the position of the prey, it misses and jammer bat has a chance to capture the prey.

But it doesn't end there. The bat that got jammed often turns the tables and jams the jammer. The two bats go back and forth in an aerial dual until one of them gives up. Sometimes a third bat might come in and it gets even more interesting. These bats are doing everything possible to outcompete each other for prey. Their lives depend on it.

I was amazed and surprised by this discovery. Bats have evolved for millions and millions of years to avoid jamming. Even humans have a hard time jamming bats with all our technology. Discovering that bats are jamming each other shows a strategy that no one has ever seen before and level of sophistication that is impressive. So next time you are at a party next to the loud obnoxious guy, be glad you're not a bat.

Other research: Moth jamming

Mexican free-tailed bats jam each other's echolocation while competing for food (image credit Nickolay Hristov)

Video on bat jamming from Science Magazine

Media Coverage

This research was covered by hundreds of media outlets all over the world. Here a links to a few of my favorites:

Scientific American

Science News

Smithsonian Magazine, National Geographic.