Male Dolphins Form Alliances And Use Individual Names To Identify Each Other
10 June, 2018, 07:11
Scientists from The University of Western Australia, University of Zurich and the University of MA, studied 17 well-known adult male dolphins in Shark Bay, Western Australia, where males are known for their formation of alliances. Analysis determined that males in an alliance kept their distinct vocal labels, which suggests that these calls may serve a goal similar to an individual name.
"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. "Dolphins use them to introduce themselves or even copy others as a means of addressing specific individuals", King continued.
The discovery paints a picture of the social intelligence of dolphins whereby no other non-human animals have been found to retain an individual "name" when they form long-term cooperative partnerships with one another.
"And this is very unusual in the animal kingdom because most animals when they form strong bonds, they will converge, they will have a group call". "Therefore, retaining individual "names" is more important than sharing calls for male dolphins, allowing them to keep track of or maintain a fascinating social network of cooperative relationships". This shows the importance of names among the dolphin community.
Dr King told the journal Current Biology: "With male bottlenose dolphins, it's the opposite - each male retains a unique call, even though they develop incredibly strong bonds".
Signature whistles of two different male dolphins from Shark Bay, Western Australia.
A bottlenose dolphin signature whistle.
Just like in early human populations, it seems that dolphins use individual vocal labels to maintain recognition within complex social structures.
Their closeness also extends to their physical touch.
Convergent vocal accommodation is used to signal social proximity to a partner or social group in many species. They then determined the individual vocal label used by individual males, and measured the similarity of those identity signals within and between alliances in order to determine whether males with stronger social relationships used vocal labels that were more alike.
After collecting the recordings, the team were able to determine the "names" or individual vocal label of each male.
These dolphins aren't born with their own signature whistle.
"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.
Drone footage shows a trio of adult male dolphins that spend time petting each other, using pectoral fins and tail flukes to rub against each other.
This may be similar to grooming behaviour in primates, which has been linked to oxytocin release.