turtles_3.jpgJustin Congdon and his chief
assistant, Roy Nagle (right),
measure larger shells such as
that of this Blanding's Turtle with
a caliper originally built for trees.
For smaller shells, they use a
digital caliper.

The two sides of Congdon's temperament— researcher and cowboy— fit naturally together, but they didn't always. Growing up in a military family, he had almost no interest in his studies and couldn't wait to come home from school to explore the swamps and woods near his house. Muskrats and water snakes held a fascination for him that classrooms and books did not. He assumed he would follow in his father's footsteps and pursue a career in the Navy, but three years of scrubbing toilets and cleaning guns on an aircraft carrier persuaded him to try college. The thought of returning to school scared him so much that as he drove to Victorville, California, to enroll in a junior college, he kept saying over and over to himself, "I hope I never get there."

turtles_4.jpgAfter this Common Snapping Turtle was struck by a car, Justin Congdon determined that her back was broken, and so he had to shoot her to put her out of her misery.

Save the Grown-ups if You Want Babies

Although his team harvested the 30 eggs she was carrying, carefully built a nest for them in a promising spot, and covered that nest with a cage, predators managed to find and eat the eggs anyway.

When we think of turtle conservation, we think of "head start" programs, in which nests are protected from predators and hatchlings are raised in captivity until the animals are old enough to survive in the wild. Meanwhile, adults are harvested on a regular basis, for the pet trade and for their supposed medicinal value. Justin Congdon's research is making a lot of people see that this scenario may be upside down: Hatchlings need protection, but adults need it even more.


"If you're interested in conserving long-lived species, what is your best strategy?" asks zoologist Ronald Nussbaum. "Most of the turtles' mortality occurs in the first year. Most of the eggs never make it. If a turtle produces 1,000 eggs, 998 of them can die as long as two of them, one male and one female, survive to replace her. So what would a conservationist do with this information? Well, you would make sure the adults survive and not worry too much about the nests and the eggs."

There's a reason wildlife managers haven't thought in those terms: Most of the animals we try to protect, such as deer, rabbits, and quail, are relatively short-lived. "With deer, you can eliminate 50 percent of the population, and two to three years later, you're back to where you were," says ecologist Whit Gibbons. "With turtles, they won't be anywhere near where they were. It takes so long for them to reach maturity that once you have an adult, you have a valuable commodity." Gibbons says protecting the adults makes sense for other long-lived species too. "This has immediate application— for whales, for elephants, for polar bears— for animals that live a long time and can't sustain the cropping they get."

— B. Y.

Just one biology class convinced Congdon that he could make a living pursuing his childhood fascinations. At 26, while working toward a master's degree in biology, he moved into an abandoned copper and silver mine in the Mojave Desert, which he furnished with cast-off carpeting and a propane refrigerator in order to study how kangaroo rats and pocket mice use different desert habitats seasonally. For four days at a stretch, he'd trap intensively on one-quarter of his grid. The work was so intense that he had to stop and take a break, hiking the Providence and Granite Mountains; then he'd return to trap another quarter. At night he'd read by taillights salvaged from an abandoned car and hooked up to the battery of his Volkswagen bus. "I hated going near civilization," he says. "I promised my parents that I'd call them every time I went out for supplies, and I did. But there were two-week periods when they didn't hear from me."

In 1975 his mentor at the University of Michigan, evolutionary ecologist and herpetologist Donald Tinkle, offered him a job on the E. S. George Reserve. The day Congdon and his wife arrived, carting all their belongings with them, Tinkle announced he was flying off to Utah to work on another study. "I said, 'You've got to be kidding,'" Congdon recalls. "I thought, 'My God, how am I going to handle this?' We left the truck half-unloaded, and Don and I went down to the swamp and checked traps, and he showed me the marking codes and where the equipment was, and then he left."

Once he had absorbed his new responsibilities, Congdon's days fell into a pleasant routine, canoeing in the wetlands to collect data on the residents. "I started trapping some marshes that hadn't been trapped, and we had a 100-turtle day when I went into East Marsh for the first time. At that point I think Don knew we were going to have a good study."

Tinkle died five years later, at 49. "I was devastated," Congdon says. "He was my mentor and academic hero." Just before his death, Tinkle called the National Science Foundation, announced he was terminally ill, and obtained permission for Congdon to run out the grant. The younger scientist vowed to oversee the project in a way that would honor his predecessor. "I wanted it to be run as good as it had been run, or better," he says. "I couldn't have had it any other way."

While crunching his data in the mid-1980s, Congdon made a startling discovery: The oldest female Blanding's Turtles— more than 50 years old— had more egg clutches than younger ones, as well as more eggs per clutch. Not only that, they died at a lower rate too. "What did I do wrong?" Congdon remembers thinking to himself. "Did I make a mistake? Did I analyze it incorrectly?" He knew that adult turtles kept growing throughout their lives, and so he wondered whether the true variable might be body size rather than age. Once he ran the numbers again, controlling for body size, he was astonished to find that he got nearly identical results.

At first, he didn't write up the findings. There was little or no conversation among gerontologists about nonhuman aging models. "I just couldn't get anybody interested in what I was doing," he says. So he resolved to bide his time, figuring that the more data he collected, the stronger his evidence would be.

As humans senesce, arteries harden, eyesight deteriorates, vital organs lose capacity, reproduction stops, and the probability of death increases. For us, this progression makes evolutionary sense: Since we spend almost two decades raising children, it behooves us to finish producing them while we're still young. Our genes favor early childbearing; they also ensure that we'll be around long enough to raise our kids.

It also behooves creatures like mice and rats to have babies early in their lives but for a different reason: If they don't, they might get eaten before they reproduce. "Even if a mouse was immortal as far as physiological death, a predator would still get it within three or four years," says Whit Gibbons, an ecologist at the Savannah River Ecology Laboratory in Aiken, South Carolina, the facility where Congdon works during the part of the year that he's not in Michigan. "Therefore, their genes operate very well at the early stages of their lives. There's no sense having a gene in a mouse that's going to work in 10 years, because there's no way those genes will be passed on."