These strategic groups help them gain access to females.
People, sometimes, are known for their cooperative relationships. The ability to create strategic alliances was thought to be unique to humans.
A new study finds, however, that male bottlenose dolphins form large networks where their partnerships assist them in their competition over females.1
Simon Allen, a senior lecturer at the University of Bristol’s School of Biological Sciences, contributed to the study. He and his team have been studying Indo-Pacific bottlenose dolphins (Tursiops aduncus) at Shark Bay in Western Australia for decades.
“With 40 years of dedicated research on this remarkable population of dolphins, we delve into many aspects of their social lives, the daily challenges they face in finding mates and food, their genetics, their acoustic communication, their foraging specializations, and how such a society beneath the waves could come to converge with our own in certain ways despite being so distantly related,” Allen says.
He points out that dolphins certainly don’t resemble humans. They don’t walk on two legs, can’t change their facial expressions, and don’t have fingers that grip or opposable thumbs. However, they share some important characteristics with people.2
“They each have individual signature whistles, equivalent to a human name, which they can use to announce their presence, call each other, or refer to one another,” Allen says. “Like us, they have extremely large brains, three times larger than similar-sized relatives; and Shark Bay’s Indo-Pacific bottlenose dolphins, in particular, also form strategic, multi-level alliances.”
It’s not a matter of what makes them so interesting, he says.
“An alternative question might be: ‘How could we not find bottlenose dolphins fascinating?’” Allen says.
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Some animals form alliances and work together, often in contests over rank or to get access to females. Lions often team up with relatives and may attempt to overthrow another alliance in an attempt to commandeer a pride of females. Some primates form coalitions, usually to get access to mates.2
“Male dolphins in Shark Bay, on the other hand, form alliances within a large, open, social network. We show that this is the largest alliance network known outside of humans, and that these alliances are not only strategic but multi-level,” Allen says.
They found that the male dolphins in Shark Bay form first-order alliances which is a team of two to three males who work together to court females. Then there are second-order alliances of four to 14 unrelated males that compete with other alliances over access to female dolphins. And third-order alliances are between cooperating groups of second-order alliances.1
“Strategic, multi-level alliance formation was once thought unique to humans, think local football team, provincial team, and then national team, or local council, state government and even international alliances—this level of cooperation is a hallmark of our intelligence and success as a species. Here we see three levels of alliance formation in a population of a species other than our own.”
For their research, scientists studied dolphin behavior and group configuration by approaching them on small research boats and photographing the animals. They did these surveys for decades and followed specific male alliances and female groups.2
“We have built up an incredibly rich and detailed picture of the population’s social lives—who are friends, who are foes, and how does this change over time?” says Allen.
The results were published in the journal Proceedings of the National Academy of Sciences.
Critical for Success
Researchers say these relationships between male dolphins are crucial for them to succeed. They determine how they are able to court females, which is critical to their reproductive abilities.
“The multi-level nature of their alliances are, to our knowledge, unparalleled in the (non-human) animal kingdom,” Allen says.
“The advantages to multi-level social cooperation in humans can be seen everywhere, in trade, military or sporting successes, for example.”