When Bats Squeak, They Tend To Squabble

If movies were trying to be more realistic, perhaps the way to summon Batman shouldn't have been the Bat-Signal — it should have been the bat squeak.

New research from the Bat Lab for Neuro-Ecology at Tel Aviv University found that bats are "vocalizing" more information than many researchers previously thought. And researchers were able to decipher what the bats were squeaking to each other about — often they were bickering over things like food, sleep and mating.

"It's not as if now we can understand everything. It's not as if we have a bat-to-English dictionary," says Dr. Yossi Yovel, a neuro-ecologist at Tel Aviv University and a member of the Bat Lab.

"But what we've found is that this cacophony that you could hear ... actually contains much more information than previously believed. So, all of [this] shouting, all of these vocalizations that were previously all categorized as aggressive vocalizations, we can now divide them," Yovel tells NPR's Scott Simon.

"For example, we can classify whether the bats are arguing over food or over mating or over sleeping position or over other contexts," he says. "We can recognize the individuals vocalizing and we can even, to some extent, say who they are vocalizing to."

In a recent study, Yovel, along with researchers Yosef Prat and Mor Taub, monitored groups of Egyptian fruit bats with 24-hour audio and video recording for two and a half months. They say they analyzed almost 15,000 bat vocalizations.

Egyptian fruit bats are one of a small number of animal species to communicate one-on-one within their species, instead of "broadcasting" their message.

Bats do more than argue, Yovel says. But Egyptian fruit bats spend a lot of time arguing.

"Nearly all of the communication calls of the Egyptian fruit bat in the roost are emitted during aggressive pairwise interactions, involving squabbling over food or perching locations and protesting against mating attempts," the researchers write.

"What they're saying is stuff like: Why did you wake me up? Get out of my way," Yovel says. "In the case of mating, it's usually the female protesting against a male who is trying to mate with her."

Context in bat communication was one focus of the study. If we humans say the word "apple," we imagine certain characteristics just from that word alone: a red color, a round shape, a certain taste, Yovel explains. "This is something that is [a] very very important factor in human communication."

He says animals almost never demonstrate this ability. But their research shows that vocalizations between bats have more of this type of context than researchers knew about before.

One goal of the research on bats is to apply it toward general knowledge of how different animals — including humans — communicate. "It's all part of a big question: How complex is animal communication?" Yovel says.

"Identifying context specific calls can be a first step toward the recovering of meaning in animal communication," the researchers write. "Understanding the encapsulated information in animal vocalizations is central to the study of sociality, communication, and language evolution."

So is there a human-bat translator in the works?

"Step by step we are getting closer to deciphering their communication," Yovel says. "I don't think we will — not in my time, at least — be able to really talk with them."

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