Wells and a specially trained crew prepare to release a female dolphin following a veterinary exam. Health evaluations are performed on a handful of animals at infrequent intervals. “We much prefer to observe the animals in the wild,” says Wells. “But some crucial information on sex, age, genetics, health, and environmental contaminants can only be obtained through careful hands-on work.” |
DNA tests made it possible to begin evaluating family relationships, mating systems, and population growth patterns
At first, because so little was known, “we asked broad-based, simpleminded questions,” Wells says. “In the seventies we believed dolphins lived 25 years. Then we found they can live to be 50 and sometimes have calves in their late 40s. We also knew zero at first about dolphin social structure, including who swam with whom and their reproduction patterns in the wild.” As the years passed, Wells recorded more than 17,000 group sightings and conducted as many as 600 observations of specific individuals. “You let the animals tell you what they’re doing,” Wells says. “You can’t go out and manipulate them.”
| Especially abundant in the Gulf of Maine; sometimes seen riding the bow waves of humpback and fin whales |
ROUGH-TOOTHED DOLPHIN | Occasionally sighted amid floating logs in the eastern tropical Pacific; its narrow head and large eyes give it a reptilian appearance |
COMMERSON’S DOLPHIN | Hunted off Chile and Argentina for use as bait in crab fisheries; sticks close to shore and sometimes enters rivers |
COMMON DOLPHIN | Numbers in the millions worldwide; large groups can go into frenzies when feeding, perhaps to panic fish |
Over the years, Irvine and Scott drifted into other career paths—Irvine now designs health-related software in Oregon, and Scott studies various species of dolphins in the eastern Pacific Ocean for the InterAmerican Tropical Tuna Commission. But Wells’s two old friends return for a week or two most summers to help with a bottlenose dolphin roundup. “It’s a social reunion as well as science,” Irvine says. With the help of a couple dozen trained volunteers, Wells and his colleagues remove from six to as many as 30 dolphins from the water for a physical.
The dolphins are encircled in shallow water with a 1,500-foot-long net and then gently lifted, one by one, onto the deck of a boat for a full health assessment. A team of veterinarians records each dolphin’s weight, sex, and blood values. They also perform a diagnostic ultrasound examination and culture blowhole swabs for respiratory-system bacteria. Separate data are taken for specific research projects, including an ongoing study of dolphin communication. Researchers record a dolphin’s voice—its signature whistle—by attaching a suction-cup microphone to the sound-producing “melon” on the animal’s forehead between the beak and blowhole. “Back in the seventies, we were just beginning to recognize the significance and impact of dolphin communication,” Wells says. “Now we’re looking at its effects on population and reproduction patterns.”
A large group of adult dolphins hitches a ride on the pressure wave from the bow of a boat. In open waters, dolphins can effortlessly cruise along at speeds of 18 to 22 mph. |
“The bay is a natural laboratory now,” Wells says. “All these dolphins know our boats. They’re tolerant and don’t change their behavior because of our presence.”
The Chicago Zoological Society, based at the Brookfield Zoo, has supported Wells’s work on the bay for the past 10 years. When Wells first forged a relationship with Brookfield, he had the choice of continuing as a single-handed researcher or leveraging his work with help from graduate students who had been exposed to the research literature and field techniques. “I went with the students,” Wells says, kicking off his boat shoes as he settles into a chair in his office. He cranks up his computer and switches on the vhf radio, which connects him to research boats manned by his staffers as well as Earthwatch volunteers and aspiring marine biologists from Woods Hole Oceanographic Institution, the University of California at Santa Cruz, and other universities.
Melon-headed Whale Travels in tight pods of up to 2,000 through the deep waters of the tropics; highly gregarious and combative
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Hourglass Dolphin
An inhabitant of remote Antarctica and subantarctic seas; named for the white patch pattern on its flanks
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Northern Right Whale Dolphin A sleek inhabitant of the North Pacific that lacks a dorsal fin; can travel 22 mph and leap 23 feet
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Long-snouted Spinner Dolphin An agile acrobat of tropical waters; can jump 10 feet in the air, spinning up to seven times in a single leap
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Long-snouted Spinner Dolphin An agile acrobat of tropical waters; can jump 10 feet in the air, spinning up to seven times in a single leap
MELON-HEADED WHALE | Travels in tight pods of up to 2,000 through the deep waters of the tropics; highly gregarious and combative |
HOURGLASS DOLPHIN | An inhabitant of remote Antarctica and subantarctic seas; named for the white patch pattern on its flanks |
NORTHERN RIGHT WHALE DOLPHIN | A sleek inhabitant of the North Pacific that lacks a dorsal fin; can travel 22 mph and leap 23 feet |
LONG-SNOUTED SPINNER DOLPHIN | An agile acrobat of tropical waters; can jump 10 feet in the air, spinning up to seven times in a single leap |
RISSO'S DOLPHIN | Perfers deep, offshore waters; develops a distinctive battel-scarred look from run-ins with other dolphins and squid |
Meanwhile, Caryn’s husband, Edward Owen, is probing a mysterious facet of dolphin social life. Detailed observation of the Sarasota population has shown that most males pair off for life with unrelated males, swimming side by side and surfacing to breathe in tandem. One possible explanation is that the dolphins buddy up for protection against sharks. More than a fourth of the dolphins in the bay carry shark-attack scars. Although dolphins don’t sleep, research with captive animals shows that half the dolphin’s brain shuts down periodically, then wakes while the other half dozes. This creates a period of rest in which the animal is probably less alert and could use a friend to keep watch. Or maybe they pair off for protection against other dolphins. Despite the benign image perpetuated by the 1960s tv series Flipper, bottlenose dolphins can be combative. “They’re aggressive,” Wells says. When males reach sexual maturity, they move into adjacent home ranges, such as Tampa Bay, seeking adventure and mates. “We’ve seen violent encounters between males from Tampa Bay versus males from Sarasota Bay, with no females present,” Wells says. “And we know from genetic tests that up to 30 percent of calves are sired by males who are not members of the community. They have battles then too.”
Or there may be an even more surprising explanation for the bonding: The males may pair off in order to gang up on females. One of Wells’s research assistants, Ester Quintana, saw two male dolphins 100 miles north of Sarasota apparently trying to force a female into mating with one of them. “One was under the female and the other was trying to mount her—like a sandwich,” she said. “They tried for 20 minutes.” Wells suspects this may not be an isolated incident. “We see pairs of males isolating a female from the rest of a group and flanking her, a male on each side,” he says. “Sometimes they flank her for hours to weeks, most likely controlling the behavior of other males and keeping them away. With male pairs in captivity doing this, they both get mating opportunities. So maybe this provides better access to females. We’ll do paternity tests and see.”
As Wells’s study gains notoriety with each passing year, more and more graduate students descend on the bay. Stephanie Watwood is analyzing the acoustic patterns of male dolphins to see how they work together. Shawn Noren is studying the respiratory physiology of young dolphins to learn how their diving abilities develop. Anna Sellas is conducting genetic studies of dolphin population structure. Kara Buckstaff is looking into how boat sounds elicit a response from dolphins and how those sounds are affected by sea grass, channels, and the physical environment. Doug Nowacek is observing dolphin foraging behavior.
Like his students, Wells is forever amazed by these enigmatic mammals. “Dolphins are truly exceptional creatures,” he says, turning away from his keyboard and gazing past the computer monitor out the window toward the blue of Sarasota Bay. Then he laughs. “Sometimes I regret sitting here listening on the radio to all the fun the graduate students are having,” he says. “I miss that, but the work is still challenging. Getting the answers is like Christmas morning—only now it’s like looking over someone else’s shoulder while she unwraps the presents.”






