Self-organized acoustic behavior in bats arises from simple rules

Although self-organized behavior has been extensively studied in the movement of group-behaving animals, such as fish or birds, far less attention has been paid to vocal behavior in animal groups, especially in mammals. Here, by testing the vocal response of echolocating bats (Miniopterus fuliginosus) to the playback of jamming stimuli in the lab, we discovered a mathematical model that can well describe vocal frequency control by bats in response to jamming stimuli mimicking echolocation sounds emitted in a group of bats. We then extended the model to a group of flying bats and observed frequency-adjusting behavior by which the frequency differences for the group increased overall, similar to a previous observation on group-flying bats. Further, we showed the frequency-adjusting behavior led to less potential misdetections by echolocation in a group. Our findings suggest this frequency-adjusting behavior is a self-organized vocal behavior that mitigates conflicts within a group, one achieved via simple behavioral rules, as in other types of collective animal behavior.