When Bats Squeak, They Tend To Squabble | KERA News

When Bats Squeak, They Tend To Squabble

Dec 31, 2016

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."

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

SCOTT SIMON, HOST:

Animals communicate - birds sing to woo their mates, the Cubs sing "Go Cubs Go," BJ Leiderman wrote our theme music, wolves howl out to their pack members and fruit bats bicker.

(SOUNDBITE OF FRUIT BATS SQUEAKING)

SIMON: That symphony of squeaks is a cave of Egyptian fruit bats as they argue over food, mates and sleeping space. Egyptian fruit bats are part of a small group of animals that communicate individually within their species - person to person, if you please, if you were a fruit bat. Dr. Yossi Yovel is a neuro-ecologist at Tel Aviv University and part of the research team that is now decoding Egyptian fruit bat banter. Dr. Yovel, thanks very much for being with us.

YOSSI YOVEL: You're welcome. Hi.

SIMON: So what are they saying to each other?

YOVEL: So it's not as if we can now understand everything, it's not as if we have a bat to English dictionary. But what we found is that this cacophony that you could hear, which is very typical if you enter a bat cave, that's exactly what it sounds like - actually contains much more information than previously believed. So all of these shouting, all of these vocalizations that were previously all categorized as aggressive vocalizations, we can now divide them. For example, we can classify whether the bats are arguing over food or over mating or over sleeping position or over other contacts. We can recognize the individuals vocalizing, and we can even to some extent say who they are vocalizing to.

SIMON: How unusual is this among animals? I mean, I know we do it, right?

YOVEL: It's only part of a big question - how complex is animal communication? When I say apple, you immediately imagine a red, round object, you know, with a certain taste. This is something that is very, very important factor in human communication. And animals have almost never been shown to have this ability. We show that bat vocalizations contain a lot of information about the context of the vocalization. For example, a third bat eavesdropping on a conversation between two individual bats can tell to some extent what is this conversation about, what is this argument about, which is more than we previously believed.

SIMON: So you mentioned food, mates and sleeping space. So does this mean the bats are saying she's mine, no, she's mine? Or I'll take that glop of whatever it is? Or you've got your claws on my head turn over?

YOVEL: Something like that. Maybe I should first point out - it's very important that bats don't only argue. OK. There are other vocalizations that bats emit.

SIMON: They support each other emotionally, I'm sure.

YOVEL: Exactly. Yeah. Some people get the wrong impression that bats only argue. We, in purpose, wanted to take this huge bulk of aggressive vocalizations and see if we can classify them. And, indeed, I think - exactly like you suggested - I think what they're saying is stuff like why did you wake me up, get out of my way. In the case of mating, it's usually the female protesting against a man who is trying to mate with her.

SIMON: Can you tell, doctor, did the fruit bats bicker much over Clinton versus Trump?

YOVEL: (Laughter) I can say that in another study we are following bats in Mexico, and these bats are actually flying over the U.S.-Mexican border, so if there is going to be a wall there, it will have to be very, very high.

SIMON: (Laughter) Is it possible that one day human beings will be able to communicate with bats and really find out about their lives?

YOVEL: You know, step by step we are getting closer to deciphering their communication. I don't think we will, not in my time at least, be able to really talk with them, so to speak.

SIMON: Yossi Yovel is a neuro-ecologist at Tel Aviv University. Thanks so much for being with us.

YOVEL: Sure. You're welcome. Transcript provided by NPR, Copyright NPR.