Bats share social information through echolocation calls

Bats share social information through echolocation calls. Bats use sound waves and echoes, or echolocation, to locate prey in the dark. A new study from the Smithsonian Tropical Research Institute (STRI) has found that some bat species use echolocation calls to identify group members and to find food faster. 

In previous work, experts have identified several ways that social  information is shared among bats through echolocation. For example, bats produce echolocation calls known as feeding buzzes to zero in on prey, and these sounds alert nearby bats to the prey’s location.

Prior to the STRI study, however, it was not known that the echolocation calls produced while bats search for food contain social information as well. 

The researchers theorized that these “search-phase” calls may also contain individual signatures that can be perceived by bats. If so, they may be able to identify each other without the need for specialized communication signals. 

To investigate whether search-phase echolocation calls carry information about a bat’s identity, the team set out to investigate whether bats of the species Molossus molossus recognized specific group members.

The experts used a cognitive experiment known as a habituation-dishabituation paradigm, during which the bats were exposed to repeating search-phase calls until they no longer reacted to them. The bats were then exposed to echlocation calls that were different yet similar.  

If the bats reacted to the second stimulus, it would show that they perceived a difference between the two stimuli.

Study lead author Jenna Kohles is an STRI fellow and doctoral candidate at the Max Planck Institute of Animal Behavior in Germany.

“We played echolocation calls from two different bats that were both group members of the subject bat,” said Kohles. “By measuring the responses of the subject bats as we switched between calls from different individuals, we could learn about whether the bats perceived differences and similarities between the calls.”

The experiment confirmed that the bats are, in fact, able to distinguish between different group members, and they likely make the distinction through individual signatures encoded in the calls. 

The findings suggest that search-phase calls not only help bats detect prey, but also convey individual identities to nearby foraging group members. This would explain why the auditory cortex of M. molossus is primarily tuned in to these search-phase calls, considering that they contain such important information. 

The research sheds new light on the social strategies bats use to meet their energetic needs, as well as the evolution of social communication in bats.

“This study suggests that we may be underestimating the crucial ways social information influences bat foraging success and ultimately survival,” said Kohles.

The study is published in the journal Behavioral Ecology.

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By Chrissy Sexton, Earth.com Staff Writer