Killer whales, much like humans, are highly intelligent animals with a complex social structure, and a new study has found that one of the apex predators of the ocean can form close friendships.
Drones followed three pods of orcas, containing a total of 72 whales, and researchers from the University of Exeter used the footage to analyse their behaviour.
They looked for signs of individuals touching and surfacing together, both indicators of a strong bond.
“Physical contact tends to be a soothing, stress-relieving activity that reinforces social connection,” said Prof Darren Croft, co-author of the paper.
The data revealed that killer whales spend large amounts of their time with certain individuals that are often of the same sex and similar age.
This is the first study of its kind to decipher the various layers of intra-pod interactions.
The drone was flown over killer whale subgroups (a). All individuals detected simultaneously were considered to be associated, and both synchronous surfacing and physical contact interactions were recorded between identified individuals (b). Examples from video stills show synchronous surfacing (c) and physical contact between individuals (d)
"Our findings show that, even within these tight-knit groups, whales prefer to interact with specific individuals,” said study author Dr Michael Weiss.
"It’s like when your mom takes you to a party as a kid: you didn’t choose the party, but you can still choose who to hang out with once you’re there."
In these matriarchal family groups, it is unsurprising that females were found to have a large amount of social clout, but so too do youngsters.
The research, published in the journal Proceedings of the Royal Society B, also found that as whales aged, the more they were pushed to the peripheries of the social group, maintaining fewer friendships.
Writing in the study, the researchers add there are striking similarities in the friendships of whales and those of other high-functioning mammals, including primates and people.
“The finding that killer whales become less social as they age aligns with social life histories found in other social mammals,” the researchers write.
“In humans and non-human primates, individuals become less social and maintain fewer relationships as they age.”