"We found that individual male dolphins retain their unique signature whistle, allowing them to recognize many different friends and rivals in their social network, something not now known from any other non-human animal", said report co-author Stephanie King of the University of Western Australia wrote at The Conversation.
It's not uncommon in dolphin society for males to form long-lasting alliances with other males, sometimes for decades.
Male dolphins use "names" to identify their friends and rivals, Australian researchers have discovered.
Pairs and trios of dolphins joined together to form larger alliances of 10-14 to help each other defend females from competing alliances or to steal females from those other groupings.
"Males retain their own individual vocal label or name, and do not make their calls more similar".
"Our work shows that these "names" help males keep track of their many different relationships: who are their friends, who are their friend's friends, and who are their competitors", Stephanie King from the University of Western Australia, one of the authors of the study, said in a statement.
"Convergence onto shared or similar identity signals has been documented in allied male bottlenose dolphins", the study said.
"We wanted to understand if allied male dolphins converged onto similar calls as a way of advertising their alliance membership, or whether they retained individual vocal labels", King said.
Dolphins may be more akin to humans than believed, said a study released on Friday, confirming that the marine mammals use individual "names" to identify friends and rivals among social networks.
Dolphins are intelligent creatures that communicate with high-frequency whistles and are capable of forming strong relationships. 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. It's not clear if this behavior is restricted only to bottlenose dolphins.
To explore the role of these "vocal signals", the team measured the similarity of the signals between and out of alliances of male dolphins.
Just like in early human populations, it seems that dolphins use individual vocal labels to maintain recognition within complex social structures.
She also learned that the dolphins can mimic each other's whistles, seemingly to address or call out to one another.
She said it meant males were able to track individual relationships, allowing them to differentiate friend from foe and many other relationships. However, they did not know how these males used vocal signals to form and maintain these relationships. That is something that would be worth investigating. "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".