When the sea is vast and the ladies are scarce, what’s a lovesick male dolphin to do? Band up with his buddies to sing some seductive "pop" songs, new research suggests.
Reporting this week in the journal Proceedings of the Royal Society B, scientists have uncovered evidence that male dolphins can synchronize their “popping” calls—vocalizations that seem to have a magnetic effect on females, who can’t help but be drawn to the noise, reports Elizabeth Pennisi for Science magazine.
The findings are so far exclusive to Shark Bay in Western Australia, where male bottlenose dolphins have been spotted teaming up in small groups to interact with potential mates. Males will often swim, turn and surface in unison around females to pen them in. These alliances can last decades, boosting males’ ability to keep tabs on females and, by extension, increasing reproductive success.
A few years ago, a team of scientists led by Stephanie King at the University of Bristol noticed a new dimension to the Shark Bay dolphins’ synced behaviors: sound. Between 2016 and 2018, the researchers recorded the vocalizations of seven groups of male dolphins, parsing out their pops, which, to human ears, sound like a series of rapid clicks, reports Gege Li for New Scientist.
In at least 172 instances, males were heard popping in harmony, generating clicks at the same time and the same rate. Because the males popped at different speeds when they made their calls solo, King and her colleagues argue in their paper that the synchronized vocalizations weren’t just happening by chance.
“Pops are only produced by male dolphins when they are herding females,” King tells Rosie McCall at Newsweek. For some reason, these vocalizations prompt the females “to stay close to the popping male.” Collaborative popping, then, may be a way for males to maximize their chances of keeping their mates nearby.
Many other animals are known to purposefully cooperate and even copy each other’s actions. Some of these displays—like the flashes of a firefly or the dances of some colorful birds—are thought to be competitive, with suitors vying for the attention of a mate. But humans, and perhaps now dolphins, are among the less common species who engage in group behavior as a form of camaraderie.
Because the researchers didn’t track the dolphins’ reproductive success, they can’t yet quantify the importance of coordinated popping. But in an interview with New Scientist, King theorizes that the harmonizing could trigger the release of oxytocin—often nicknamed the “cuddle hormone” for its prominent role in the formation of social bonds—and improve male-to-male communication.
Also important, of course, are the reactions of the popping males’ audience: females. “It would be really interesting to see how female dolphins react to such displays,” Julie Oswald, a biologist at the University of St. Andrews who wasn’t involved in the study, tells New Scientist. While pops may be heard as threatening noises, mandating that females keep close, “synchrony between two males could also be attractive to females.”