Female Dolphins Seem to Remember Which Males Were Aggressive During Mating Season—and May Try to Avoid Them

When researchers played underwater recordings of pushy males, females that were capable of becoming pregnant swam away from the sounds

Sarah Kuta | Daily Correspondent

June 23, 2026 10:00 a.m.

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Humans remember when they’ve been treated badly and often use those past experiences to decide who to spend time with—and who to avoid. Now, new research suggests female bottlenose dolphins may rely on a similar strategy for managing their relationships.

According to a study published on June 1 in the journal Proceedings of the National Academy of Sciences, female Indo-Pacific bottlenose dolphins can identify males by their “signature whistles,” or unique noises that individual dolphins make to identify themselves, similar to a nametag. Females seem to use the whistles to remember which males were pushy and aggressive during past mating seasons and may try to avoid those individuals moving forward.

“Females are using knowledge of individuals. That, to me, is super interesting,” Laela Sayigh, a cetacean behavior and communication researcher at the Woods Hole Oceanographic Institute who was not involved with the study, tells National Geographic’s Bethany Augliere. “To my knowledge, this is the first time that there really has been a study of how these communication signals are used in mate choice.”

Found in the tropical waters of the Indian and western Pacific oceans, Indo-Pacific bottlenose dolphins are similar to their common bottlenose relatives. However, the Indo-Pacific variety has a longer beak, a more slender frame and distinct dorsal fins; members of this species also tend to prefer shallow, coastal waters.

The new research offers a window into the complex social lives of these highly intelligent creatures. Males and females often get along in harmony, engaging in positive behaviors like touching and petting. But come mating season, males often start behaving more aggressively toward females.

They engage in what’s known as “consortship,” which occurs when multiple males gang up on a single female to mate with her. They herd her, guard her and restrict her movements during these events, which can last anywhere from a few hours to a few weeks. These consortships often turn violent, with males charging, biting and hitting females to keep them subdued. Female dolphins, it seems, remember these encounters and may learn to avoid the most aggressive males based on their signature whistles.

Researchers reached this conclusion after studying bottlenose dolphins in Shark Bay, a UNESCO World Heritage Site in Western Australia. They recorded 34 signature whistles from 11 male dolphins, then played them back to 17 females via underwater speakers. The team used a drone to observe the females’ behavior, watching to see whether they swam toward or away from the sounds. They also measured the distance they traveled and the duration of their response.

Females that were “reproductively available”—capable of becoming pregnant based on age and time in their reproductive cycle—showed a strong avoidance response to the whistles of aggressive males. Females that were not capable of getting pregnant, such as those that were raising calves or were older, showed a much weaker avoidance response.

“When we were playing back these male whistles, sometimes the females freaked out, and they really left and went away,” lead author Alice Bouchard, a biologist who conducted the research at the University of Bristol in England and now works for the International Whaling Commission, tells National Geographic.

The female dolphins seemed to react not only to males they’d had bad personal interactions with, but to individuals that had a broader history of aggression toward females throughout the social circle.

Female dolphins, the researchers suspect, may be using past experiences to navigate their relationships with males. This makes sense, given that consortship is “costly” for females, the researchers write in the paper. By avoiding pushy males, females are also avoiding risks like physical injury, reduced foraging time and loss of mate choice.

Mike Bossley, an independent cetacean researcher in Australia who was not involved with the research, applauded the study, telling the Guardian’s Petra Stock it confirms the “complexity of dolphin societies.” Females seem to be getting to know “each male’s personality—and using that information to help choose who will father their calf,” he adds.

The discovery “tells us something important about which male traits females are tracking,” Bouchard tells National Geographic. But moving forward, researchers hope to explore additional questions, such as how exactly females learn which males to avoid.

They also want to explore the specific characteristics and behaviors that might make a male dolphin attractive, rather than repulsive, to reproductively available females, since those individuals would have a higher likelihood of reproducing and passing along their genes.

Sarah Kuta | Read More

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.