Young dolphins choose their friends wisely, and with the future in mind, according to a new study from Duke University. The researchers report that in childhood, wild bottlenose dolphins strategically build social networks that will benefit them in adulthood.
The study was focused on three decades of records for more than 1,700 wild bottlenose dolphins in Shark Bay, Western Australia. Scientists have been observing dolphins and documenting their characteristics and behavior in this region since the 1980s.
For the current investigation, the team analyzed data involving young dolphins from weaning to age 10, examining what they did and who they spent time without adult supervision.
At age three to four, the youngsters leave their mothers and venture out on their own. The juveniles form dynamic groups that are constantly splitting up and meeting up again in different combinations.
According to the study, even though the young dolphins bounce from group to group as often as every ten minutes throughout the day, they spend more time with a few close friends.
The research suggests that the animals are not simply choosing their close friends out of convenience because they share common space or keep bumping into each other. Study first author Allison Galezo explained that the relationships “reflect true preferences.”
Males preferred friendships with other males and females with other females, but the boys and girls were found to interact in different ways. For example, females socialized less often than males and spent twice as much time foraging for fish. Males were more likely to spend their time together resting or engaging in friendly physical contact by rubbing flippers, swimming close together, and mirroring each other’s movements.
These differences suggest that the social lives of young dolphins may be shaped by the upcoming demands of adulthood, said Galezo.
“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.”
Among the males, having reliable friendships and strong alliances will be important for passing along their genes. In Shark Bay, groups of two to three male dolphins often join forces to get fertile females alone and coerce them to mate.
Among the females, success in adulthood means caring for calves that are not weaned until they are at least three years old. Nursing moms need more calories, so young females spend more time foraging to practice skills they will need the most later in life.
The study is published in the journal Behavioral Ecology.