Bat besties start to sound alike over time

Ever suddenly realize you had picked up certain words or ways of speaking from a close friend?

Maybe they spoke to you in a certain drawl or twang, or used slang like “y’all” or “yinz,” and you mirrored their expressions back to them.

It turns out that humans are far from the only animals who copy the sounds of their closest companions — a new study shows that vampire bats do, too.

Research published in the journal Proceedings of the Royal Society B shows that female vampire bats match the calls of those closest to them as they forge new friendships.

In the study, scientists brought together female vampire bats, some that had met before and some strangers, in cages in the lab and watched as they got to know their new roomies.

Vampire bats are more than just flying bloodsuckers with sharp front teeth. They’re also intensely social creatures who look out for each other just like us.

Vampire bats live in tight-knit communities in which females build reciprocal relationships with other females they’re not related to. If you’re a vampire bat — the only bats in the world that feed on blood — that means regurgitating into your friends’ mouths to keep them from going hungry, expecting that they’ll eventually do the same for you.

But they don’t share blood meals with just anyone. Vampire bats only share their dinners with a few special partners that they befriend over time.

In the experiment, the team tracked the development of bats’ relationships based on which females ended up grooming one another or sharing food. They then analyzed the similarities in the bats’ contact calls, the loud high-pitched sounds they use to keep track of each other as they fly or crawl around in the darkness.

We can’t hear most of the sounds bats make. They navigate, hunt and communicate with each other using ultrasonic frequencies that aren’t perceptible to the human ear.

So researchers record them with special equipment and then use spectrograms to visualize the collection of frequencies that make up their calls.

In total, the researchers analyzed nearly 700,000 contact calls recorded from 95 bats over the years by placing each bat inside a recording booth.

Sure enough, when vampire bats found themselves in a new social group with unrelated strangers, they altered their calls to match those of bats they met, said Julia Vrtilek, first author of the paper and a graduate student at The Ohio State University.

But they didn’t just take on the sounds of their loudest or chattiest cage-mates. Instead, food-sharing companions came to sound more alike than less chummy pairs.

This means females are learning their calls by listening to each other as they interact, rather than simply making the sounds they’re genetically predisposed to make, said co-author Grace Smith-Vidaurre, 1855 Assistant Professor of Data Science in STEM at Michigan State University in the Departments of Integrative Biology and Computational Mathematics, Science, and Engineering.

It’s possible that vampire bats are just learning the sounds they hear most often, similar to the way people acquire regional accents or local dialects, said senior author Gerald Carter, Associate Professor of Ecology and Evolutionary Biology at Princeton University.

In that case, having the same “accent” could be a way for the bats to tell familiar individuals from strangers.

Or it could be that matched calls help companions build rapport, or they simply make it easier to understand one another or reunite in a noisy crowd, Carter added.

A similar behavior has been noted in humans, as we’ll sometimes “code switch,” or adjust our communication style based on who we are with, said Smith-Vidaurre, who is also core faculty in MSU’s Ecology, Evolution, and Behavior Program.

Beyond bats, soundalike partners have also been observed in dolphins, parakeets, elephants and monkeys.

As a next step, the team is looking at whether vampire bat females consistently use the same calls to address particular partners — essentially calling each other by specific “names.”

“Bats have amazing vocal flexibility, but it's relatively understudied beyond their use of sound for echolocation,” Carter said. “This study is just the tip of the iceberg.”

This research was supported by a grant from the National Science Foundation (IOS-2015928).

CITATION: "Vocal convergence during formation of social relationships in vampire bats," Julia K Vrtilek, Grace Smith-Vidaurre, Eric Fosler-Lussier, Rachel A Page, Gerald G Carter. Proceedings of the Royal Society B: Biological Sciences, Nov. 12, 2025. DOI: 10.1098/rspb.2025.1619