Dumbo, Jumbo, Babar, Surus.

Those are some of the well-known names humans have given to elephants.

But what names do elephants go by among their peers?

It’s a question that researchers at Colorado State University have begun to unravel, thanks to a groundbreaking study released this week.

Elephants in the wild identify one another by distinct audio signatures, similar to the way humans use names, the study found.

“We found that elephants address one another with calls that are specific to the individual receiver,” Mickey Pardo said Friday on a Zoom call with the Coloradoan and two other news outlets. “In other words, the calls contain some information that identifies who the intended recipient of the call is.”

Pardo, a behavioral ecologist, is the lead author of the study that was published in Nature Ecology and Evolution.

While working as a post-doctoral researcher at CSU, in a study funded by the National Science Foundation, Pardo spent 14 months in Kenya studying elephants in their native habitat. Pardo and other researchers followed the elephants in a vehicle and made both audio and video recordings of their vocalizations, according to Source, an online publication of CSU’s marketing and communications team.

They gathered about 470 distinct calls, captured from 101 unique callers corresponding to 117 unique receivers in Samburu National Reserve and Amboseli National Park. The recordings were made during two separate trips, one lasting four months in 2019-2020 and one lasting 10 months in 2021-22, Pardo said.

“The first step was actually to collect audio recordings of the elephants, where we knew who made the call and who the call was addressed to,” Pardo said. “And then once we had that data set of calls with known receivers, we were able to use a machine-learning model to see if we could predict who the receiver of a call was just from the sound patterns of that call.”

Kurt Fristrup, a research scientist at CSU’s Walter Scott Jr., College of Engineering, developed a signal processing technique to detect subtle differences in call structure, according to the story in Source. And he and Pardo trained a machine-learning model, Random Forest, to correctly identify which elephant a call was addressed to based only on its acoustic features.

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“And then the second stage of the study was to play calls back to the elephants and see if they would react more strongly to a call that was originally addressed to them than to a call from the same caller that was originally addressed to someone else,” Pardo said. “Then we videotaped those trials so that we could more objectively score the elephants’ response rather than try to do it in real time in the field.”

The audio recordings were collected with a hand-held microphone, he said, capable of capturing sounds below the range of human hearing.

“Our ears can’t even hear the full call,” he said. “The difference is quite subtle, at least to our ears. I really needed the machine-learning analysis to discern those patterns in the data.

“Obviously, the playback experiment showed that the elephants can hear the difference just fine. But for us, at least for me, it was too subtle to notice in the field.”

George Wittemyer, a professor in CSU’s Warner College of Natural Resources and chairman of the scientific board Save the Elephants, was Pardo’s supervisor at the time and is a co-author of the study, as is Joyce Poole, co-founder and director of Elephant Voices.

Pardo said he was reading an article about bottlenose dolphins identifying one another by mimicking the receiver dolphin’s unique whistle when he first became curious about whether elephants — one of the only other mammals with the ability to learn to produce new sounds — did something similar.

That was in 2012, he said, and he was a first-semester graduate student at Cornell University in New York, where he now is a post-doctoral researcher. He didn’t have the resources to perform that research at the time. After coming to CSU and bouncing the idea off Wittemyer, they worked together with Poole and others to secure the necessary funding from the NSF.

Wittemyer and Poole, he said, already suspected elephants had unique names for each other based on their observations.

“They had seen situations where sometimes an elephant would make a call, and the whole family would respond, and sometimes they would make a call and only one individual would respond,” he said.

The distinctive sounds elephants are using the way humans use names, he said, is only a small portion of the communication with one another he and other researchers observed. It’s possible, he said, that elephants also have assigned names to food, locations, inanimate objects and a variety of other things.

The next step for researchers, he said, is to figure out exactly how individual names are embedded within elephants’ calls. Their presence was proven through variations in the calls, “but we weren’t able isolate the names of specific individuals in this study.

“If we can isolate the names for specific individuals, we can start to ask all sorts of other questions, like how do elephants acquire their names in the first place? Do they ever talk about each other in the third person? How are they using these names in actual context. And all of those questions would be a lot easier to address if we could say with confidence, ‘This is the name for this individual, and this is how it’s encoded in the call.’”

Although other mammals are able to communicate with one another and capable of learning to respond to specific names, “vocal production learning, or the ability to learn to produce new sounds is pretty rare in animals, because you need specialized neural circuitry to do it,” he said. “And it’s not just a question of general intelligence. Like chimpanzees can’t do it, either, and they’re our closest living relatives and super smart. It’s about having that specialized neural circuitry to be able to hear something and then reproduce it based on your auditory experience.”

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Bottlenose dolphins and parrots are the other animals known to use distinct sounds to address specific members of their species, Pardo said. Other species of dolphins, and possibly whales, might be able to do the same, he said. A 2016 study suggested Egyptian fruit bats might also have that ability, and some songbirds defend their territory against other songbirds by singing whatever song the other last sang “as a way of letting them know they’re focusing on them,” he said.

The study’s findings might shed some light on how humans learned to communicate, he said.

“Vocal production learning, the ability to learn to produce new sounds, is fundamental to human language,” Pardo said. “We couldn’t have language without it. But it’s not clear why our species developed that in the first place.

“It’s possible that given that we now have three other animal species that have name-like calls, that all use their vocal production learning ability to learn names for each other, that maybe that’s how that ability evolved in humans, as well. And that we originally started out with a need to call one another by name, and so we developed vocal learning ability because it was advantageous to call others by name. Then, once we had that ability, it allowed for more sophisticated language to develop.”

Reporter Kelly Lyell covers education, breaking news, some sports and other topics of interest for the Coloradoan. Contact him at kellylyell@coloradoan.com, x.com/KellyLyell and  facebook.com/KellyLyell.news. 

This article originally appeared on Fort Collins Coloradoan: Elephants call each other by unique names, CSU study finds