Baywatch: Studying Bottlenose Dolphins

They're sexy, smart, sociable, playful, fast, and very independent—no wonder biologist Randall Wells has spent more than 30 years spying on bottlenose dolphins.

By Jack McClintock|Wednesday, March 01, 2000
RELATED TAGS: ANIMAL INTELLIGENCE

"Dolphin," Randall Wells says calmly, adjusting his sunglasses and pointing across the light chop on Sarasota Bay. Wells, a conservation biologist, plants his feet and spins the wheel of his 18-foot open fisherman, veering toward the spot where he's glimpsed a sleek dorsal fin under the Lido Key Bridge. Stocky and tanned at 46, Wells bends over the wheel, breathing in the addictive scent of fish and salt water as he squints into a perfect Florida winter day of warm sun, chilly breezes, and sharp black shadows. Fifty feet ahead, the dolphin rolls up and chuffs exhalation through its blowhole. 

“It’s Nicklo,” says Wells, recognizing her immediately. He gave her that name because of a low nick in her fin, possibly from an encounter with a shark or a spinning outboard propeller motor. “She’s 49, one of the oldest known reproducing female dolphins in the world. We’ve seen her with four calves over the years. She had one last year.” He points. “See?” A second, smaller, silver body surfaces. As the boat idles, biologist Sue Hofmann picks up her camera and snaps pictures of Nicklo and the calf. In the bow, an Earthwatch volunteer reaches for a clipboard and scribbles time, water temperature, location, salinity, and other facts next to Nicklo’s formal name: FB15. Then, the two animals vanish. Wells throttles back and creeps along under the bridge, his eyes penetrating the glint on the water with help from polarized sunglasses. “Well, she sure gave us the slip,” he says.

Wells punches the throttle and wheels the boat off in a long curve toward deeper water, in search of other old friends. “Some of the dolphins stick to us like glue out here, but others don’t want anything to do with us,” he says. Over the past three decades, he has come to know most of Sarasota Bay’s 120 resident bottlenose dolphins by sight, and chronicled each dolphin’s family history and its individual quirks. Heading up the longest-running wild-dolphin study ever conducted, he has become the world’s leading authority on a creature whose domed forehead and fixed grin invite both affection and misunderstanding. “The dolphin’s smile is a fact of anatomy, not attitude,” he notes crisply. “They’re not little people in wet suits.”

“Randy knows more about bottlenose dolphins than anyone,” says John Reynolds, chairman of the U.S. Marine Mammal Commission. Wells and his colleagues in the Sarasota Dolphin Research Program have produced more than 100 articles for a variety of scientific publications. They clarified dolphins’ feeding patterns (by analyzing stomach contents); showed a connection between high levels of chlorinated hydrocarbons in dolphins’ blood and immune-system dysfunction; learned how dolphins interact with increasing boat traffic; did field tests to see if calves responded to their mothers’ signature whistles (they did); and used dna analysis to determine dolphin social structure.

“Scientifically, it’s important to know how dolphin social structure works and how it compares with other mammals—lions, great apes,” and other marine animals, says Wells’s mentor, marine biologist Blair Irvine. “And Randy has written the book on the health of a population of wild animals. For example, if we see a dolphin die somewhere else, we can look at its blood values and compare what we find with this laboratory herd in Sarasota to see if it’s normal or not.”

Wells, who lives next to these creatures on the narrow, 18-mile-long bay and often sails it in his little Sunfish, never tires of watching them: “They’re living in our backyards, almost literally, and living a life so different from ours, so successfully.” His work is far enough along that every revelation he makes about dolphin life seems to punctuate a new enigma. For instance, his ongoing survey of this bottlenose population reveals that 85 percent of their firstborn calves die. The cause is a focus of his research. Another puzzle: Over the years he has discovered that most male dolphins pair off with other males at an early age and bond for life.

Bottlenose dolphins (Tursiops truncatus) inhabit a mosaic of overlapping communities along Florida’s Gulf Coast, traveling back and forth to mate and feed. One of 30-odd species of the delphinidae family of toothed whales—of which the largest is the orca, or killer whale—the bottlenose grows to nine feet long and 600 pounds, eating 30 pounds a day of fish such as pinfish, pigfish, and mullet. In summer, when the water is at its warmest, females give birth to nearly blubberless babies. Just after the birth of a calf, the mother lunges away from it sharply, thus snapping the umbilical cord and freeing the calf to swim up to the surface for its first breath. Soon the baby is nursing, which may continue for several years. It begins eating fish from the age of six months or so, sometimes grabbing large prey and rubbing it on the ocean floor or smacking it on the water’s surface to break it into bite-size bits. Some youngsters play cat-and-mouse with their catch, letting them escape and recatching them. “I’ve seen dolphins tossing small stingrays around like Frisbees,” Wells says.

Dolphins are sociable creatures, and most of what is known about how they relate with one another has emerged because of Wells’s work. Mother and young form a bond that remains intimate for three to six years, often as part of a group of mothers and calves that may include three generations. Older sisters and aunts sometimes baby-sit while mothers take a break. Eventually mother and calf part, although many maintain a relationship for the rest of their lives. The young dolphin joins a juvenile group, and for the next dozen years they hang out, leap, bite, chase fish, and have sex, generally behaving like rambunctious teens. As they mature, most males split off into pairs and seek mates outside their community. Females, soon pregnant, find themselves part of a mothers-and-calves group.

Although parallels to human life are easily drawn, Wells is careful not to anthropomorphize dolphins. Still, language slips between brain and lips from time to time. “It’s really neat the way they are,” he might say, with a grin as boyishly enthusiastic as the one he must have worn at 15, when he moved with his parents to Sarasota Bay from landlocked Peoria. He arrived in 1969, “a bright kid who loved the ocean,” says Irvine. Before long, young Wells found his first job at the Mote Marine Laboratory, founded by pioneer shark researcher Eugenie Clark of the University of Maryland. “He really got into it,” Irvine remembers. “He was shy, and dedicated as all get-out.” Wells chopped fish, cleaned tanks, and helped with Irvine’s early dolphin research into whether dolphins could be trained to protect divers and shipwreck victims from sharks. (They couldn’t.)

One day, Irvine and marine mammal veterinarian Jesse White, who was known for having the same passionate interest in manatees that Wells later developed for dolphins, were talking shop. A question came up: Where do dolphins live? At the time, nobody knew. Irvine decided to find out. He hooked up with a commercial dolphin-catcher who netted the animals for aquariums. He freeze-branded them with liquid nitrogen—labeling them FB1, FB2, and so on—and began tracking their movements. Wells was allowed to tag along. Before long he met Granny, Melba, Hannah, Nat, and Nicklo, dolphins he would see hundreds of times over the decades. “I found out later he was cutting school to go on collecting trips,” Irvine says, laughing. “He just had this drive to do it, and even though I was a fairly cynical scientist then and told him there were no jobs, no money, no chance of much of a career, he wouldn’t quit.” Before long, Wells was cited as coauthor on a scientific paper by Irvine entitled “Results of Attempts to Tag Bottlenose Dolphins.”

When he first arrived at Mote, Wells was mostly interested in sharks. But as he worked with Irvine, he became a dolphin man. He grew fascinated by their combination of apparent friendliness and remoteness and how they used their intelligence in ways we didn’t understand. And he found that dolphin research had an advantage over shark research: “It’s easier to study something that comes to the surface every 28 seconds to breathe than something that never comes up at all.”

He went away to school, but he kept coming back. At the University of California at Santa Cruz, he wrote a Ph.D. dissertation about spinner dolphins in Hawaii and did postdoctorate research on bowhead whales in the Arctic. But three times a year he made his way to Sarasota Bay to follow the bottlenose. In 1982, he teamed up with Irvine and marine biologist Michael Scott to form the Dolphin Biology Research Institute. As his fascination grew, Wells became more and more like a sociologist venturing into a forbidden land, writing down everything he learned about the society he found there. “They’re definitely individuals; they have their own ways of doing things,” he says. “The species’s hallmark is behavioral flexibility.” Rose feeds along the seawall rather than in open water. H lurks under bridges. Blacktip Doubledip always shows a corner of its tail when it dives, in a kind of flippant farewell wave. Pecan Sandie delights in what scientist-observers call “kerplunking,” driving its entire tail—fluke, stock, and barrel—powerfully down into the water, sending up a column of spray. Some of the dolphins enjoy bow-riding—leaping from the water near a boat’s bow wave—and some don’t. Large males tend to be especially slow and stolid, perhaps because they have little to fear or prove. “Some very quickly come up to the boat and some never do, some will look at you and others don’t seem to care,” Wells says. Each individual has its signature whistle. And, like Nicklo, most are readily identifiable by a glimpse of their fins, tails, or bodies. Riptorn’s dorsal fin was left tattered by a boat propeller; Sharkbait has shark-attack scars on its body.

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.”

He overcame a major problem in wildlife research—data can be skewed by the human penchant to record only behavior that we find interesting—by recording specific observations every three minutes: where the dolphin is, who it is with, what it is doing. He trained himself to take only physiological data in between, no matter what the dolphin was doing. As technology improved, Wells found ways to use it. He discovered it was easier to see through murky water with a remote-control video camera mounted on a tethered baby blimp. And he added dna tests, which made it possible to begin evaluating family relationships, mating systems, and population growth patterns. “DNA fingerprinting didn’t exist in the seventies,” Wells says. “Now it’s a major part of what we do.” If a calf’s mother is known, taking DNA from the calf and from adult males can disclose who the father was, which can reveal breeding patterns within and between dolphin communities. Wells and his fellow researchers found that Sarasota Bay females, for example, often breed with roving males, including some from Tampa Bay to the north.

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.”

Some dolphins seem to enjoy the procedure. A few approach the research boat, allow themselves to be hoisted up, then bask on deck, looking around with apparent interest and whistling at others in the water while the team of researchers and volunteers shades the dolphins’ eyes from the sun and splashes cooling water on their skin.

“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.

Wells spends a lot of time indoors these days, manipulating computer data and raising grant money. But more manpower has produced better dolphin data faster, and that’s what he cares about. More data continues to produce more mysteries, too, such as the recent discovery that 85 percent of firstborn dolphins don’t survive to become adults. Wells, restless in his bay-view office, can’t wait to find out why. “Nothing is simple with dolphins,” he says. Pollution could be the cause. Toxic runoff accumulates in dolphin tissues over time, and researchers in South Africa have found that when females lactate, they purge most of that accumulation. That means vulnerable firstborns ingest a lifetime of poison with their mothers’ milk. Perhaps it weakens or kills them. Or perhaps new mothers aren’t as wise or as careful as experienced moms are. Under Wells’s supervision, Caryn Owen is investigating the role of maternal experience in calf survival, monitoring how much time mothers spend with their calves and how close they stay together. In Owen’s study, as in almost every dolphin study on the bay nowadays, Wells’s 30 years of data is a crucial foundation. “Caryn can go to the computer, pull up every dolphin’s reproductive history, and tell which ones have had calves and which are likely to be calving,” he says.

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.”

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