Nature Wise: Why dolphins form, maintain bonds

Skylar and Booya are two of the bottlenose dolphins being monitored by the Outer Banks Center for Dolphin Research.

Science is full of questions, and one of the most interesting questions I have found about dolphins is why they form and maintain their social bonds. As we spend more time out on the water each summer studying the dolphins in Roanoke Sound, we learn more about who likes to hang out with who, where everyone likes to go, and other gossip within the groups. With new discoveries come more questions! And when you think you have finally figured it out, something happens that throws off your entire theory!

Bottlenose dolphin adult males are known to form lasting pair bonds, one of the only types of bonds known in dolphin societies. Males receive many benefits from pairing up together. Environmental benefits include assistance in finding food and better protection from predators. Socially, males have better access to the girls (aka an easier time finding a date) if they are part of a pair. The strategy of forming pairs (or even trios) is popular amongst bottlenose dolphins studied throughout the world. Through the Outer Banks Center for Dolphin Research (OBXCDR) long-term photo-identification study, we have documented these bonds within the Outer Banks dolphin groups as well.

When I first began working in the Outer Banks, I learned the names of dolphins that frequent Roanoke Sound as well as the male pairs. It was well known that Onion and Pinchers were always together, shadowing each other side by side. Bud and Moe were another frequently seen pair, the “old guys” of the sound, swimming slowly next to each other patrolling the channel near the Wanchese marsh. Other pairs that I came to know were 708 and Sequoia, who were frequently seen herding females in the channel, Rake and 92, and Sprite and Cola. These male pairs were consistently seen together, and seeing one without the other may an indication that something was wrong. Indeed, when Pinchers passed away in 2012, we were tipped off to his passing by a solitary Onion showing up multiple times in Roanoke Sound. These male pairs seemed to be stable across years as well as in their winter study site in Beaufort, NC.

Naturally, when Rake showed up one day without 92, our research team suspected the worst. However, little did we know, Rake would be the dolphin to teach us about the flexibility of male pairs in Roanoke Sound. 92 turned out to be fine. We saw him several times that summer in groups without Rake. Rake, on the other hand, paired up with Rainbow, a large male and also a member of our seasonally resident community in Roanoke Sound. We were astonished to find Rake and Rainbow surfacing synchronously together as a pair for several years. Last summer, Rake again switched his pair and joined up with another adult male, Cola. Cola had been paired for several years with Sprite. Since Cola paired with Rake, Sprite has paired with Skylar. Another long-time pair, 708 and Sequoia, has recently split as well with Sequoia pairing with Jetson and 708 being sighted alone. Although we can’t be sure as to what triggered these changing association patterns, it has really become quite a soap opera out in Roanoke Sound.

But bottlenose dolphins are highly intelligent and socially complex, leading us to believe these changing association patterns are strategic moves to enhance their existence. As long-lived top predators, dolphins are important indicators of environmental health, and learning more about the local dolphin population can provide insight into the health of our marine environment, which much of our local economy depends upon. A healthy dolphin population is a good indication of a thriving environment. Perhaps modifications to their pairs are a response to changing environmental conditions? Or maybe there is a new girl in the sound that the males are trying to impress? The answer to this question will be found in future monitoring efforts and a close watch on the “boys” in the sound. Regardless of the reason for these strategic changes, our dolphins definitely seem to subscribe to the theory that a wingman is always a good idea.

Biologist Jessica Taylor is executive director of the Outer Banks Center for Dolphin Research. Taylor has a bachelors of science degree in marine science from Rutgers University and a masters of coastal environmental management from Duke University. She has participated in several field research studies of bottlenose dolphins, humpback whales, Stellar sea lions, and predatory fish in Florida, South Carolina, Australia, Alaska, and New Jersey. In 2008, she incorporated the nonprofit Outer Banks Center for Dolphin Research, which is dedicated to conservation of bottlenose dolphins in the Outer Banks.

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