Female dolphins remember who is aggressive when choosing a mating partner, research shows

Researchers observed unavailable female dolphins – those that were older, or with calves – did not show the same avoidant behaviour

Female dolphins identify males by their unique calls and keep track of their past behaviour, choosing to avoid the most aggressive males during mating season, new research suggests.

Bottlenose dolphin society is complex, and male and female dolphins often know each other for decades, said Prof Stephanie King, an expert in animal behaviour at the University of Bristol.

These relationships could be positive, she said. Males might perform displays to impress the females, or engage in affiliative behaviours like touching or petting, a bit like holding hands in humans.

But during mating season, the males often worked together – in pairs or trios, and larger alliances – to gain access to females by aggressively herding them into “consortships”, mating events that could last anywhere from hours to weeks.

King said the male dolphins would “work together to keep her with them for as long as possible,” adding that sometimes they could be “quite coercive”.

“They’ll restrict the female’s movements. They’ll want to keep the females in the areas that they prefer, because then they’re near other males that can help them defend that female from rivals.”

Female dolphins likely observed these behaviours over time, and avoided the more aggressive males, according to research published in the Proceedings of the National Academy of Sciences.