In a new study, Harish Prakash and Rohini Balakrishnan from the Centre for Ecological Sciences (CES), with collaborators from Tel Aviv University, explored whether calling in a group reduces risk for katydids (bush crickets) against bats, which are their predators. They found that bats were more attracted to three speakers simultaneously playing katydid calls than a single speaker. Does this mean calling together in a group might be riskier? Yes. But that is just one part of the story.

The researchers also found that bats took considerably longer to capture a katydid calling in a group of three than a lone katydid. This delay gives the katydid an opportunity to stop calling, and escape from being eaten. Therefore, although a chorus of katydids can attract bats, the bats’ inefficiency in capturing them when they are in groups can benefit the prey.

A possible reason for the delay is the confusion effect: it is harder for a predator to target and capture an individual when it is among many others. Previous studies have looked at this only in visual predators like monkeys, geckos and fish. This study provides the first evidence of an auditory confusion effect in eavesdropping predators such as bats.