Before translocation, before Fort Irwin, before Westward expansion, before the Mojave was even a desert, tortoises browsed the West. The desert tortoise's ancestry goes back about 19 million years. Fossils have been found in White Pine County, Nev., more than 100 miles from the species' present range. Tortoises once roamed California's Orange County and Central Valley. Their genes carry adaptations to the tremendous changes that turned woodlands to grassland, then grassland to desert succulents and creosote scrub. Today, they're found in portions of the Mojave and Sonoran deserts in California, Nevada, Utah and Arizona.

Unlike their gigantic, lumbering Galapagos Islands cousins, desert tortoises are high-domed, light-stepping, almost jaunty little animals, 15 inches long on average. They browse on cactus, wildflowers and grasses, and their stout front legs make them excellent diggers of dens. They play a keystone role in the ecosystem: Their burrows shelter other species and they stir up and aerate the soil and disperse plant seeds. Long necks, handsome faces and curious gazes have helped earn them "state reptile" status in both California and Nevada.

They are one of the most studied turtles in the United States. But it was not always thus. Back in the 1860s, a scientist plucked a specimen from the desert, pickled it in formaldehyde and named it Gopherus agassizii –– "Gopherus" after gophers and "agassizii" in honor of Swiss paleontologist Louis Agassiz. It took another 70 years before two Utah scientists started wondering how the animals survived in such extreme conditions.

Angus Woodbury and Ross Hardy monitored a colony near St. George, Utah, from 1930 to 1947, studying how tortoise shells harden, noting how few hatchlings escape the jaws of foxes and coyotes, observing that some tortoises were gregarious while others were shy. Tortoises, they saw, had an excellent sense of color and might mistake pink clothing for edible flowers. They can go for a year or more without water because half their weight is stored in their bladders; if you disturb one, it might release all that liquid on you, then die from dehydration. Perhaps most intriguing, they concluded that most of the tortoise's energy didn't go to sex or foraging. Instead, it went to negotiating Mojave temperature swings between zero and 130 degrees Fahrenheit -- digging deep dens to escape freezing, finding shade to cool off. And the animals were attached to those dens; when carried out of their home range, they made frantic beelines back.

After Woodbury and Hardy, a quarter century passed before another researcher applied the same kind of dedication to studying Gopherus agassizii. But rather than focus on a single colony, Berry studied dozens in a sweeping effort to define its range in the western Mojave Desert.

"Intelligent … serious … formal": These are some of the words that a member of her University of California, Berkeley thesis committee used to describe Kristin Berry in 1971. Meet her once and you start choosing your words carefully. She listens so intently and answers questions with such clarity that an encounter with her is like wandering into a spotlight. Steve Schwarzbach, Berry's supervisor at the USGS, remembers when she met a photography crew in Ridgecrest, Calif., in May 2000 to lead a tour. As she was crossing a street, the perhaps 5-foot-3-inch, 110-pound scientist was struck by a car.

"Not a small car, something like an Impala," says the director of the Western Ecological Research Center in Sacramento. "She was hit so hard that she was thrown from a pedestrian crossing. But she led the tour before getting treatment," despite injuries severe enough to later require two back surgeries.

The daughter of a physicist at the China Lake Naval Air Weapons Station, Berry grew up north of Los Angeles, out where the Mojave Desert meets the Sierra. So many wildflowers bloomed after winter and early spring rains that tortoises browsed until their beaks ran green. "I once saw eight in one place," says Berry, recalling how common the reptiles were.

She was preparing a doctoral dissertation at UC Berkeley on the chuckwalla lizard, a stocky Southwestern cousin of the iguana, when she became a teaching assistant for Robert Stebbins, author of the Peterson Field Guide to Western Reptiles and Amphibians. Her thesis committee included Starker Leopold, son of legendary ecologist Aldo Leopold, and David Wake, then director of herpetology at Berkeley's Museum of Vertebrate Biology. "Bob was not typically very close with his students," says Wake. "Kristin was an exception. I think Bob saw in Kristin someone really dedicated to conservation."

In 1971, her dissertation delivered, Berry received a call from the California Department of Transportation, which was widening Highway 58 through tortoise habitat. She knew about herbivorous reptiles, right? "They had already marshaled the Boy Scouts and they were going to dump the tortoises on China Lake," she says. "They released them in July, which was the worst possible time. We had to pull the ones we could find, because they couldn't dig a burrow fast enough to get out of the heat and were foaming at the mouth." She realized then, she says, "Nobody had any idea what they were doing with translocation."