Bat Cries Are Used for Communication and Contain a Surprising Amount of Information

A team of researchers has found that bats use noises to communicate with each other. For the first time, bat calls were analyzed in a laboratory. The team found that the cries included information such as identity and context. The details are in a paper that was just published in the journal Scientific Reports.

Egyptian fruit bats (Rousettus aegyptiacus) are noisy creatures, especially when clustered together in caves. While their cries had been recorded previously, scientists weren’t sure if they were simply basic noises or an actual form of communication. Egyptian fruit bats are long-lived, social, and intelligent—making them a perfect species to study.

Researchers from Tel Aviv University observed a population of 22 captive Egyptian fruit bats to learn more about their vocalizations. The bats were captured in Israel and kept in large acoustic chambers fitted with cameras and an advanced voice-recognition system. The animals were monitored for a total of 75 days and the team collected data from 19,021 individual calls. Even after discarding cries with poor data or no obvious context, the team had nearly 15,000 vocalizations to analyze.

The researchers sorted out different types of vocalizations with voice-recognition software and determined that the calls were used for communication. Bat cries contained information such as the identity of the sender, the identity of the target individual, and context. The authors noted that many of the vocalizations were being used to express irritation when other bats got too close. Other cries were used in disagreements about food, danger alerts, or to reunite with a specific individual. Interestingly, bats adapted their cries when addressing the opposite sex, changing their “tone.”

The team’s findings provide new insights into how bats communicate in crowded environments. The screeches and cries convey more information than scientists expected; the calls contain identity information, context, and tone. The researchers are continuing their study with younger bats to determine if the calls are innate or learned from others.

REFERENCE

Prat Y, Taub M, Yovel Y. Everyday bat vocalizations contain information about emitter, addressee, context, and behavior. Scientific Reports (2016).

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