We’re Starting to Understand What Bats Are Saying
A new study listens in on the spooky mammals and decodes some of the things they're screeching about.
Bat caves can be noisy places, filled with screeching residents who seem to have a lot on their minds and would probably shout in all-caps if they used social media. Is the din just so much sound and fury, signifying nothing? Not according to researchers who have listened in on the animals and found meaning in the noise.
In a new study published in the journal Scientific Reports, scientists from Tel Aviv University (TAU) captured 22 Egyptian fruit bats from a natural roost in Israel and housed them in large chambers that would allow the animals to be monitored visually and acoustically over the course of more than two months.
The goal? To find out what all of the yelling was about.
"Previous research presumed that most bat communication was based on screaming and shouting. We wanted to know how much information was actually conveyed, and we wanted to see if we could, in fact, extract that information," explained TAU study lead Yossi Yovel, in a statement.
Yovel and his team did just that. Their bat observations yielded recordings of some 15,000 vocalizations – the sum total of all the chatter passed between the bats, generating dozens of specific calls – and there was in fact a great deal of significance to the sounds.
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After poring over the audio, the researchers say the calls not only identified the calling bat but also conveyed information about the bat being called. What's more, different calls were used for different situations – usually aggression-filled encounters, the team observed. Even friends or foes greeted each other with different calls.
"We have found that bats fight over sleeping positions, over mating, over food or just for the sake of fighting," said Yovel. "To our surprise, we were able to differentiate between all of these contexts in complete darkness, and we are confident bats themselves are able to identify even more information and with greater accuracy. They are, after all, an extremely social species that live with the same neighbors for dozens of years."
Yovel said the findings indicate bats aren't merely hard-wired for certain kinds of communication but instead learn to communicate different things, adding that his team's work could teach us more about the evolution of communication itself.
"Specifically," Yovel said, "one big unknown in the world of animal communication is their grasp on semanticity – i.e., when you hear the word 'apple' you immediately imagine a round, red fruit." Finding out that bat calls contain information about the caller and the bat being called, he noted, "implies that there is a recognition factor." Discovering context in the conversations similarly adds to our knowledge about animal communication.
Yovel is currenty studying the use of accents in bat calls as well as how the creatures form into different social groups.