Dolphins that play together get the girls together, WA study finds

Male dolphins who play together as juveniles grow up to be more successful as adults, a joint study between the University of Western Australia and the University of Bristol in the UK has found.

In an international collaboration for the Shark Bay Dolphin Project, researchers spent 32 years tracking the behaviour of Indo-Pacific bottlenose dolphins in Shark Bay.

These findings show that young male dolphins with strong social bonds tend to practise immature versions of reproductive behaviour in a play setting.

The juvenile male dolphins who spend more time practising these behaviours in play will father more offspring as adults, which according to lead author Dr Katy Holmes, provides a rare link between juvenile social play and reproductive success in a wild animal.

“What we found was that the time the dolphins spent engaged in these play behaviours predicted how many offspring the males would eventually sire as adults,” she said.

The behaviours the young dolphins displayed in their reproductive play were varied, ranging from mirroring herding females to imitating low frequency pulsed vocalisations, or “pops”.

Before reaching adulthood, male dolphins often bond closely with other young males through play, and as a result long-term relationships are formed within these groups, with friends later assisting each other in securing female mates.

It’s been found that these younger groups of male dolphins mirror and practise the adult group’s behaviour of working in alliances to attract or herd individual females, often with their likely allies, long before they reach maturity.

This herding behaviour also involves the “pop” sounds, to prompt a female to remain close.

“This specifically happens when they are play-herding with females, mimicking the adult call context,” Holmes said.

However, the pops produced by the youngsters aren’t up to the same standard as the adult males, and it seems the juvenile males need practice through play to achieve the same quality mature males do.

This practice play helps the more social young dolphins become more successful in their reproductive endeavours as adults.

It was also observed that pairs of young males with stronger social bonds were more likely to coordinate their play behaviour to mimic mature adults synchronising their movements to keep track of a female.

The report’s senior author, Dr Stephanie King from the University of Bristol, said the reasons that wild animals engaged in play had long remained a mystery.

“This study provides compelling support for the idea that animals in the wild play together to practise behaviours that will be important for them as adults, and that if they practise enough, they will be more successful as adults,” Dr King said.

The Shark Bay Dolphin Project focuses on bringing together expertise in animal behaviour, communication, genetics and ecology, and is currently led by researchers in Switzerland and the UK who maintain strong links with UWA.

Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.