SHARK BAY — Female dolphins in Shark Bay, Western Australia, avoid aggressive male dolphins during mating season by recognizing their individual signature whistles, according to a new study. Researchers played 34 recorded male signature whistles underwater to 17 female dolphins and used drones to observe their responses.
During mating season, male dolphins form alliances in pairs, trios, or larger groups to herd females into consortships that can last from hours to weeks. These consortships often involve coercive behaviors such as biting, hitting, or charging, which can cause physical injury and disrupt the female’s foraging time.
The study found that reproductively available females showed stronger avoidance responses to the whistles of males known for higher rates of coercion. Females that were not reproductively available—such as those with calves or older individuals—did not exhibit the same level of avoidance. "Unavailable females—those that were older or with calves and unlikely to be targeted—did not show the same level of avoidance response," said Professor Stephanie King, animal behaviour researcher at the University of Bristol.
King explained that male dolphins restrict female movements and attempt to keep them near other allied males who can help defend against rivals. She added that dolphins use signature whistles to track individual behavior over time and make informed decisions. "Male and female dolphins can use signature whistles to track individual behavior over time and use that information to inform decision making," she said.
Bottlenose dolphin society is highly complex, with males and females often maintaining associations for decades. Male dolphins also use signature whistles to recognize each other and manage social relationships, and they sometimes perform displays or engage in affiliative behaviors like touching to court females.
The research focused on a population of Indo-Pacific bottlenose dolphins in Shark Bay that has been studied for over 40 years. The study provided data on each male’s signature whistle, individual behavior, and the timing of adult female estrus.
Dr. Mike Bossley, an Australian cetacean researcher not involved in the study, described the findings as evidence that female dolphins use knowledge of male personalities to influence paternity. "The research demonstrates that female dolphins use knowledge of individual male personalities to help choose who will father their calf," Bossley said.