Dolphins form friendships just like us, study finds

Dolphins
© Dolphins in Monkey Mia, a marine reserve near Denham, Shark Bay. Photo: Benny Marty

Bottlenose dolphins have close bonds that last for years based on common interests.

News that dolphins form friendships may not come as much of a surprise to anyone paying attention to the animal world, but a new study sheds some light on just how much they do it like we do.

When it comes to finding their BFFs, dolphins form their friendships with other dolphins with whom they have a common interest. The findings, published in the Proceedings of the Royal Society B by an international team of researchers, adds more insight into the social habits of these ever-fascinating creatures.

For the research, scientists dove into, so to speak, the lives of a noteworthy population of Indo-Pacific bottlenose dolphins in the Western Australian World Heritage area of Shark Bay.

These dolphins are unique in their use of marine sponges as foraging tools (you can see more about how they use the sponges in the video at the bottom); they are the only ones to ever have been observed doing this. The method is taught by mothers to calves and helps the “spongers,” as the ones who do it are called, find food in deeper water. Both male and female dolphins can be spongers, but the study focused just on males.

bottlenose dolphinStephanie King/CC BY 4.0

The researchers used behavioral data from 124 male dolphins collected over the course of nine years; for the study, they chose a subset of 37 male dolphins; 13 spongers and 24 non-spongers.

They found that the spongers spent more time with other spongers and that the bonds were based on similar foraging techniques and not relatedness or other factors.

"Foraging with a sponge is a time-consuming and largely solitary activity so it was long thought incompatible with the needs of male dolphins in Shark Bay - to invest time in forming close alliances with other males," says Dr. Simon Allen, a co-author of the study and senior research associate at Bristol's School of Biological Sciences. "This study suggests that, like their female counterparts and indeed like humans, male dolphins form social bonds based on shared interests."

Interestingly, while male spongers spent a lot more time foraging – and less time resting and travelling – than did their non-sponger counterparts, both groups spent an equal amount of time socializing. (Suggesting the importance of a good social life for dolphins!)

Manuela Bizzozzero, lead author of the study at the University of Zurich, says, "Male dolphins in Shark Bay exhibit a fascinating social system of nested alliance formation. These strong bonds between males can last for decades and are critical to each male's mating success. We were very excited to discover alliances of spongers, dolphins forming close friendships with others with similar traits."

You can see more here: Tool use and social homophily among male bottlenose dolphins. And the video below, which is separate from the study, shows how these dolphins use sponges for foraging.

Dolphins form friendships just like us, study finds
Bottlenose dolphins have close bonds that last for years based on common interests.

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