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Male bottlenose dolphins synchronise their calls to attract females

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By Gege Li Bottlenose dolphins sync up their calls to attract femalesJeff Mondragon / AlamySynchronised swimming is a signature trait of bottlenose dolphins. Now, it turns out that male dolphins coordinate not only their movements but their vocalisations, too. This may mean they’re working together to attract females. Stephanie King at the University of Bristol,…

By Gege Li

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Bottlenose dolphins sync up their calls to attract females

Jeff Mondragon / Alamy

Synchronised swimming is a signature trait of bottlenose dolphins. Now, it turns out that male dolphins coordinate not only their movements but their vocalisations, too. This may mean they’re working together to attract females.

Stephanie King at the University of Bristol, UK and her colleagues studied seven groups of male bottlenose dolphins living in Shark Bay in western Australia between 2016 and 2018. They recorded calls from 59 individual dolphins that males make to draw females towards them and away from rivals. These clicking noises are called “pops”, and the dolphins make about 6 to 12 per second.

Due to strong competition between groups, these male dolphins usually work together to attract females. Males from Shark Bay form particularly large alliances of up to 14 individuals that can last decades, with members playing different roles within the group.

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“[There is] this nested level of alliances within alliances and that is unique to Shark Bay,” says King.

The team towed underwater microphones through the bay to listen in on the dolphins. They found that the animals synchronised their pops, matching each other’s tempo and starting and ending their series of pops at the same time.

Due to the complexity of their multi-level alliances, Shark Bay dolphins are an ideal population to look at coordination, says King. She thinks this acoustic coordination could apply to other populations of dolphins too, such as those in Florida that are allied in pairs.

Though it isn’t yet clear whether harmonising their pops results in more reproductive success, it may be important to male dolphins for maintaining social bonds and reducing stress, possibly by the release of oxytocin, says King.

The oxytocin interpretation is still speculative, says Susanne Shultz at the University of Manchester, UK. It’s surprising how regular some of the dolphins’ synchrony is and documenting these vocalisations is “likely to open up a raft of possibilities” for patterns associated with hunting and play, she says.

“It would be really interesting to see how female dolphins react to such displays,” says Julie Oswald at the University of St Andrews, UK. “Pops are often described as aggressive sounds, but the synchrony between two males could also be attractive to females.”

Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2019.2944

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