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Dolphin Tweens: Boys Frolic, Girls Fish

Madison Miketa, Ph.D., Shark Bay Dolphin Project

In a study that will likely not come as a surprise to our women readers, researchers have determined that male dolphins between birth and age 10 spend more of their time hanging out with other males, while females the same age spend their time foraging for fish. 

To come to their conclusion, researchers at Georgetown and Duke Universities analyzed nearly 30 years of records on over 1,700 wild bottlenose dolphins in Shark Bay in Western Australia. They first noticed that young dolphins tend to hang out with members of their own sex. They do so after leaving their mothers around age three and tend to change social circles quite a bit—sometimes as quickly as every 10 minutes—forming cliques that eventually break up to form new configurations. 

BFFs

Despite this youthful penchant toward socializing, the researchers also noted that both male and female dolphins formed close relationships with just a few other dolphins of the same sex—but that their activities while hanging out with these “best friends” were quite different. Males rested together or engaged in play, which consists of mirroring each others’ movements, rubbing flippers and swimming close to each other. Females, on the other hand, spent nearly twice as much time as the males foraging for fish.

So what’s behind the differing behaviors? 

As is often the case with the young of any species: sex.

In Shark Bay, groups of two to three adult male dolphins will work together to get a female to go along with them to mate. So learning how to get in close with other males is a key element of their ability to get lucky when they get older. Females, on the other hand, need to take care of any calves that come of those unions until the young one is about three years old, so learning how to gather fish to feed the family is a critical skill for them to learn.

Put another way: boys will be boys, and women will do all the work.

“The juvenile period can be an opportunity to develop social skills that will be important in adulthood, without the high-stakes risks that go with sexual maturity,” said Allison Galezo, a biology Ph.D. student at Duke. Galezo is the first author of a paper reporting the findings in the journal, Behavioral Ecology.