Dolphins make unique whistles to say 'hello'
Washington: Dolphins are well known for their playful and gregarious nature. Now, a new study has found that these mammals use specific melodies called signature whistles to introduce themselves when they meet new groups.
These melodious exchanges are the key part of a greeting sequence that allows dolphins to recognise each other in the wild, researchers said.
"It's not just 'I'm so-and-so,' but the other information also in that whistle is, 'I'm so-and-so, and I'm interested in making contact in a friendly way, I'm not attacking'," study researcher Vincent Janik, an expert in animal communication at the University of St Andrews in Scotland, said.
Signature whistles of dolphins were first discovered in the 1960s, but new research is the first to reveal how these sea mammals use the sounds when one pod meets another in the ocean, LiveScience reported.
For their study, published in the journal Proceedings of the Royal Society B, Janik and his colleagues used special arrays of underwater microphones to follow bottlenose dolphin pods in St Andrews Bay as they swam around and interacted with other groups of dolphins.
They used a statistical method to tease out patterns in signature whistles (those whistles that dolphins develop as their personalised calling card) and differentiate those noises from the other chirps and squeaks dolphins produce
In cases where dolphin pods joined and swam together, the team found, such meetings were preceded by one dolphin in the group producing a signature whistle and another dolphin in the second group answering.
When dolphin groups swam by one another and didn't join, these meet-and-greet whistles were absent, the team found.
The "greeting ritual" may not require every group member to introduce themselves, because dolphins can use echolocation to determine the size of the other group, Janik said.
The researchers, however, weren't able to pinpoint which dolphin individuals made the signature whistles, so they don't know if each dolphin pod has a designated social chairman or if any dolphin can pipe up and propose a get-together.
It's likely that there is no designated leader as dolphin groups tend to be fluid and lack a stable commander-in-chief, Janik said.
According to the researchers, the dolphin calls are very important as they are one of the few animals that makeup new sounds.
Social primates know each other from the sounds of their voices, but they don't create signature identification calls.
Dolphins, on the other hand, start developing their own whistles at just a few months of age. They're also verbally adept, capable of mimicking the songs of other animals and even using particular sounds to refer to specific objects in captivity, almost as if they're using words.
"What I found really rewarding is to be out there and see how they communicate amongst themselves," Janik said.
"These are wild groups that are just doing whatever they're doing. It's really the first time that we can pinpoint down two individual groups and how they interact in a vocal domain, which is really cool."