You may know that bats bounce sound waves off objects to build a sensory map of their surroundings, a sort of sonar effect called echolocation. When sound waves bounce off prey, mainly insects, bats hone in on the signal to locate their meal.
Sonar can be blocked, though. And one study has found that Mexican free‑tailed bats block their fellow bats' sonar signals when competing for food.
The study began by looking at something else: how tiger moths fend off big brown bats by jamming their sonar signals. But when the researchers analyzed the acoustic data they also noticed calls made by Mexican free‑tailed bats that had been flying high above when the scientists recorded the moth calls. And they found that the Mexican bats were making sounds very similar to the tiger moth's sonar‑disrupting calls.
The Hunting Success of Mexican Free-Tailed Bats
In a follow‑up study, the researchers recorded Mexican bats out on the hunt, making sure to capture what they thought were sonar‑jamming calls. They then tested the recordings in the field. When they played the sonar‑jamming signal just as a bat was about to catch an insect, the bat was nearly 86% less likely to succeed. But when they played the signal at other times, or altered the signal's pitch, it had no effect on hunting success.
It's no surprise that, like most animals, bats compete for food. But it is surprising that bats use sonar not only to locate their next meal but also to prevent their fellow hunters from doing the same.
"Bats Make Calls to Jam Rivals' Sonar--First Time Ever Found" (National Geographic)