Georgetown College. Georgetown University.

By Katherine Morrissey

The walls of Dr. Janet Mann’s office are decorated with photographs of dolphins. A Professor of Psychology and Biology at Georgetown University, Dr. Mann can identify each of these dolphins by name. Some were calves when she first encountered them, others pregnant mothers or juveniles. All of them are a part of the Shark Bay Dolphin Research Project, the second-longest-running dolphin field study in the world.

The Shark Bay project involves more than a dozen different researchers from around the world, each studying different aspects of bottlenose dolphin biology and behavior.

“Over the years we’ve collected data on about 1,500 different dolphins,” says Dr. Mann, “but we’ll actually see between 400 and 600 in any given year.”

Dr. Mann and her fellow researchers track birth and death rates, relatedness (genetics), and shark attacks. They also monitor where dolphins range, how long they nurse, their hunting techniques, and their courtship behavior. Dr. Mann first joined this project as a graduate student in 1988, beginning with the Dolphin Mother-Infant Behavioral Ecology Project, a longitudinal study that has looked at more than 110 calves born to more than 70 mothers.

“I’ve always been interested in mother and infant relationships,” explains Dr. Mann, “particularly the trade-off between resource acquisition and caregiving.”

Dr. Mann spends each summer in Australia collecting data and following different mother and calf pairs. She wakes up each morning and identifies which pairs of dolphins she wants to find and observe that day. She and her team then set out in their boat to find the mother and calf pairs. They also collect data on the other dolphins encountered throughout the day.

“This means we assess identity, location, activity, and other behavioral and ecological information,” explains Dr. Mann. “New scars or changes in fin shape are noted and photographed. With the focal mother-calf pair, we use both ‘point’ and ‘continuous’ sampling for three or more hours on a given day. Each minute, we record mother-calf distance and activity, who is in the group, and location. We collect continuous dive information and time the duration of mother-calf contact.”

Over the years, Dr. Mann has found that child rearing involves a significant time commitment for dolphins. They have one of the longest developmental periods of any mammal, with calves nursing between 3 and 8 years. Dolphins are also able to live between 30 and 40 years, and female dolphins typically do not become pregnant before they are 12 years of age.

“These patterns are part of slow life histories thatcorrelate with complex learning, large brain size, and tool use,” says Dr. Mann. “Dolphins seem to excel at innovative learning, or plasticity. I examine the development processes involved to see why they excel.”

One specific area Dr. Mann is researching involves the point at which a calf is weaned from its mother and what influences the timing of this occurrence. Given that weaning can take place within the range of 3 to 8 years of age, what accounts for the wide variety in ages? Are dolphin calves showing competency at certain skills, which enables independence?

“For example,” Dr. Mann explains, “swimming is a basic competency all calves have, but diving takes a few years to become proficient at.”

Dr. Mann also monitors the skills that pass from parent to offspring. These competencies typically involve hunting techniques (including tool use with marine sponges) and social patterns. She has found that some dolphins are more social than others and travel in groups, while others remain solitary. For males, group alliances are particularly important as adults, so Dr. Mann pays particular attention to how social their mothers are and how this influences the development of both male and female social relationships in their offspring.

“When the mothers are solitary,” she explains, “the daughters seem to be okay. They can still learn how to hunt and survive in their environment. Sons of solitary mothers, however, work harder to find other male companions while they are young, so they can practice forming the alliances that they will rely upon as adults.”

After almost 20 years of work, Dr. Mann continually finds new questions to research. She also works with her students on their own research questions, both on the Shark Bay project and in the classroom. Dr. Mann teaches Animal Behavior, Monkeys, Apes & Humans, and Evolutionary Perspectives on Cognition and Development at Georgetown and also takes up to four students with her to Australia each year, giving them the opportunity to learn the latest field research techniques.

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