Dolphins name friends to recognise them

Henrietta Strickland
June 10, 2018

Researcher on male and female bottlenose dolphins shows that their names play a role in alliances that are formed between males. These alliances can last decades, and have been the subject of intense study for decades as well.

They found that males within an alliance use vocal labels that are quite distinct from one another, indicating that they serve a similar goal to names among humans.

"These alliances retain individual vocal labels, or "names", which help males keep track of their many different relationships: who are their friends, who are their friend's friends, and who are their competitors".

They plan on playing the "names" of individual males back to each other and seeing how males respond to members of their alliances in different contexts.

This is an unexpected finding as it is well known that animals that form strong social bonds will vocally accommodate one another, making their calls more similar.

The researchers wanted to know if allied dolphins shared similar calls as a way to advertise their alliance, or if they stuck to individual vocal labels.

Yet, it appears that in the complex network of dolphin alliances in Shark Bay, retaining individual "names" is more important than sharing calls. This shows the importance of names among the dolphin community.

According to the study's lead author Dr Stephanie King of the UWA Center for Evolutionary Biology, no other non-human animal has ever been found to do this, even when forming long-term cooperative partnerships. Most of the males in this study had signature whistles that were notably different from those of both first-order and second-order alliance partners.

"However with male bottlenose dolphins, it's the opposite - each male retains a unique call, even though they develop incredibly strong bonds with one another". This way they're able to negotiate a complex social network of cooperative relationships.

A bottlenose dolphin signature whistle.

After collecting the recordings, the team were able to determine the "names" or individual vocal label of each male.

The alliances can be so close that the male dolphins will begin to touch each other. However, they did not know how these males used vocal signals to form and maintain these relationships. "The bottlenose dolphin is, so far, the best studied small dolphin species, but evidence suggests that other species, such as spotted dolphins and common dolphins, also have signature whistles".

Male dolphins also use physical signals such as caresses, slaps and synchronized behavior to express their social bonds.

"This included petting, stroking and performing synchronous behaviours as an alternative means of advertising their strong social bonds", Dr King said.

"At the moment we're looking more closely into the relationships among the males in an alliance to find out whether or not they're equally strong between all the individuals involved", explains Krützen.

Other reports by Click Lancashire

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