Suddenly, a triumphant cry rings out - "Turtle!" - and a hand gently scoops up the creature.
A rescue squad of environmentalists, researchers, state employees and contractors is working against the clock to save Eastern box turtles that would otherwise be crushed or buried alive when hundreds of acres of woods in the Washington suburbs are paved over for a major highway, a process that could begin within weeks.
Turtles found on the expeditions are being put on the safe side of a mesh fence.
"It is literally do or die for the box turtles in the first phase" of the highway project, said Susan Hagood, a wildlife expert with the Humane Society of the United States, who searched with her dog, Drew, who was trained by the customs service.
When the 18.8-mile InterCounty Connector, commonly known as the ICC, is finished, it will include a permanent fence, along with culverts to allow turtles to cross the road safely to make use of all their old haunts on both sides of the road. Larger passages will accommodate wildlife of all sizes.
Concern about roadkill has led to the proliferation of such "critter crossings," as the Federal Highway Administration calls them, over and under roads around the country.
But relocating wildlife in the path of road construction is a new idea in Maryland and rare throughout the country. Last year, Florida began requiring the relocation of gopher tortoises before any new construction project begins.
The need for relocating turtles is simple. Unlike many other animals, they "can't get out of the way of bulldozers," Hagood said.
While, it's unclear exactly when those bulldozers are coming, the rescuers have to act now because the turtles soon will burrow into the topsoil for the winter. Once that happens, not even the best canine nose or the sharpest human eye will be able to find them.
Eastern box turtles can grow up to 8 inches long under their pretty, patterned shells and are found up and down the East Coast and as far west as Texas. Many biologists fear their numbers will soon dwindle because of modern dangers.
The turtles are slow to reproduce, and animals that thrive in the suburbs - such as raccoons, skunks and opossums - like to snack on turtle hatchlings and eggs. Encounters with cars and lawnmowers are deadly.
The ICC - envisioned by regional planners since the 1950s and championed as a vital link among the population and job centers of Montgomery and Prince George's counties - has raised the ire of environmentalists, who fear traffic from the road will diminish air quality and who lament the destruction of hundreds of acres of forest.
Bill Schultz, a biologist with the U.S. Fish and Wildlife Service who pushed for the ICC turtle relocation, said he knew of no similar efforts anywhere and had some hesitation about advocating a project that focused solely on one species.
"This is a big commitment by state highway," he said. "They've really stepped up."
Turtle relocation is included in the lump sums of the design-build contracts for the ICC, but is estimated to cost several hundred thousand dollars, said ICC spokeswoman Fran Counihan. In addition, the state is paying about $300,000 for a three-year study by Towson University in Towson, Md.
The study will focus on how well relocated turtles adapt and whether the fence is effective in keeping them out. Ninety-four turtles have been outfitted with transmitters, allowing the researchers to track their location.
Officials hope the study will answer the question, "Is this worth spending the public's money to do?" said Rob Shreve, an environmental manager at the Maryland State Highway Administration.