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Friday, Sept. 19, 2014

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Biologist flies with the birds

An important part of Martin Wikelski's research in ecology and evolutionary biology is bombing along back roads of Illinois in an old truck in the middle of the night.

A typical trip starts in the evening near the University of Illinois at Urbana-Champaign, where Wikelski and colleagues trap a bird -- a common migrating songbird, the Swainson's thrush -- and attach a lightweight radio transmitter to its back. Armed with a radio receiver and a map of the graph-paper-like grid of roads that blankets the Midwest, the group releases the bird and shoves off.

"We always get stopped by the police," said Wikelski, an assistant professor in ecology and evolutionary biology. "We don't drive like crazy, but sometimes we have to drive a little faster."

The trip ends at dawn, 400 to 600 miles north of their starting place, when the bird comes to roost. Often it's in a backyard on a residential street. The house is still dark, but the researchers are eager not to lose track of a night's worth of research. Wikelski knocks on the door.

"First they think we're crazy, because we just overnighted and we look like madmen," he said. "But when they find out what we're doing they invite us in for coffee."

Perhaps by the second cup they'll hear a story that connects their backyard with an ambitious and far-reaching research effort. Piecing together insights from fieldwork in the American Midwest, Panama and the Galapagos, Wikelski hopes to discover fundamental principles about how life is organized.

He studies the relationship between animal physiology and broad patterns in the way animals live their lives. He asks, for example, whether American songbirds live short lives because they invest their energy into hatching large broods, compared to long-lived tropical birds that hatch smaller broods over many years. How much energy do long-lived birds invest in a good immune system? Perhaps, Wikelski believes, there are unavoidable tradeoffs that evolution has dictated, not just to birds, but to many forms of life.

"Maybe there are fundamental constraints on long life or life in general," he said.

Physical and intellectual drive

Such questions demand more than American songbird data. Wikelski has spent much of the last 15 years on five continents tracking down animals from sea lions to lava lizards. He began his fieldwork as an undergraduate in his native Germany, continuing through research that led to his 1994 Ph.D. in zoology from the University of Bielefeld, Germany. A series of postdoctoral positions with the Max Planck Society, the Humboldt Society, the University of Washington and the Smithsonian Tropical Research Institute brought him to Panama and the Galapagos Islands.

In September 2000, after two years at the University of Illinois, Wikelski came to Princeton along with his wife, Michaela Hau, who studies reproductive cycles in tropical birds and also is an assistant professor of ecology and evolutionary biology.

Tall and thin with a quick smile, Wikelski seems to relish the combination of physical and intellectual adventure of his work. In Panama, he recently started a new project in which he and a team of graduate and undergraduate students trap ocelots, which are small wildcats. While he is not in the jungle, he keeps up with the successes and setbacks of his students via e-mail. Senior Nic Petry spent part of last summer working with a graduate student from the University of Panama tracking down ocelots and attaching radio-microphone collars. The researchers now listen in on the animals' lives, from their habits in killing prey to their respiratory rates while sleeping.

"For us, it's a stepping stone to a bigger picture," Wikelski said of the ocelot research.

Practical findings

On the way to his big-picture goal, Wikelski has uncovered important practical findings. In the Midwest, he was surprised to find out that many migrating birds stop over in suburban yards, rather than in more remote woodlands. It suggests that residential areas are vital habitats, he said. "If you keep your hedge in nice shape and don't spray all the bugs away, you become an important provider of habitat for about 60 Swainson's thrushes."

In the Galapagos research, Wikelski showed that the level of stress hormones in iguanas is an accurate predictor of the overall health of the lizards' population.

Wikelski made these findings with the support of funds strung together from an array of sources, including his department, the Princeton Environmental Institute and private foundations. He said he has found little grant money available for wide-ranging comparisons between species. Indeed, Wikelski said he is sometimes criticized for attempting "apples and oranges" comparisons in studying so many different kinds of animals at once, even in comparing temperate and tropical birds.

Yet he believes the comparisons can be valid, and are in fact the only way to discover broad patterns in evolution, understand biodiversity and, ultimately, reveal the links between these subjects and genetics.

"What has changed in the genomes of these animals to make these other changes happen?" he asked. "The genome sequence data itself does not tell you much. I think it is really important to get at the link between the environment, physiology and the genome."

To answer these questions, Wikelski always returns to birds. "Birds are very good models because we know so much about their life histories -- I mean, there are all these bird-watchers out there and we really rely on them," he said.

He also is able to study them in the lab. He is building a quarantine station in Guyot Hall so he can bring birds from other countries to conduct tests on their immune systems, their metabolisms and other physiological systems. Sometimes he brings birds to a facility in Europe where they fly in a wind tunnel and researchers take a variety of measurements. The birds stay in cages in which they are free to enter and exit the wind tunnel, like hamsters on a running wheel. "They love it, they absolutely love it," he said.

For Wikelski, studying birds offers more than just data. A long night of chasing a Swainson's thrush across hundreds of miles is a unique opportunity to understand how the bird lives. "It feels like you know exactly what the bird is doing," he said. "It's really like flying with a bird."

Contact: Marilyn Marks (609) 258-3601

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