Bats say 'back off' to each other as they swoop for yummy bugs

Thu Mar 27, 2014 12:41pm EDT
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By Will Dunham

WASHINGTON (Reuters) - The sound made by a male big brown bat as it zeroes in on a bug that might make a tasty meal - if another bat doesn't get there first - is a sequence of chirps beyond the range of human ears.

But to another bat, the meaning is unmistakable: "Back off."

Scientists said on Thursday they have identified a previously unknown call made by these bats - different from the sonar-like echolocation used for mid-air navigation and hunting - that tells another foraging bat to keep away from their prey.

The call is made exclusively by the males of this species for reasons that are not entirely clear. And the other foraging bats seem to honor the request, the researchers found.

The discovery indicates that acoustic communication in these flying mammals may be more sophisticated than previously thought and underscores the importance of vocal social communication for these nocturnal insect-eating animals, the researchers said.

"Bats may be avoiding aggressive interactions with the other bat," said University of Maryland biologist Genevieve Spanjer Wright, who led the study published in the journal Current Biology.

"Chasing and even occasional physical contact have been observed in this species during foraging flight, so use of - and response to - social calls could be a way to limit the need for aggressive interactions or even injury to the responding bat," Wright added.

The big brown bat, whose scientific name is Eptesicus fuscus, ranges from Canada through the United States, Mexico, Central America and northern South America.   Continued...