A new study has found that male bottlenose dolphins form the largest multilevel alliance network known outside of humans.
The research focused on 121 male dolphins at Shark Bay, 750 kilometers north of Perth, and involved scientists from the University of Western Australia, University of Bristol, University of New -South Wales and the University of Massachusetts.
Co-lead author Dr. Stephanie King, an assistant researcher in the UWA School of Biological Sciences and the UWA Institute of Oceans, said cooperation between allies works well for humans in as a species as well as for the dolphins in Shark Bay.
“Cooperative relationships between groups, rather than alliance size, allow males to spend more time with females, increasing their chances of reproductive success,” Dr King said.
Co-author Dr Simon Allen, an assistant researcher at UWA and the UWA Oceans Institute, said dolphins in Shark Bay form first-rate alliances of two to three males to cooperatively search for opportunities to mating with females.
Second-order alliances of four to 14 males competed with other alliances over opportunities to marry female dolphins, and third-order alliances occurred when different second-order alliances associated.
“How long these teams of male dolphins associate with females depends on whether they are connected well not only within the second-order alliance, but also with third-order allies, i.e. the social bonds between alliances are important and lead to long-term benefits in terms of mating opportunities,” Dr. Allen said.
He said researchers were concerned about the impact of climate change and recreational fishing in Shark Bay, a Marine Protected Area and UNESCO World Heritage Site.
“This dolphin society is uniquely complex and this is almost certainly linked to the huge seagrass beds that support an incredibly rich and diverse ecosystem,” said Dr Allen.
“Resilient ecosystems need nurseries, like seagrasses, just as they need apex predators, like big fish and sharks.”
The article, Strategic Intergroup Alliances Increase Access to a Contested Resource in Male Bottlenose Dolphins, was published in The Proceedings of the National Academy of Sciences.
