Two hours after the last glimmer of sunset has faded to darkness, Travis Glenn is sprawled on his belly at the bow of an air boat.
Up ahead, in the glare of a halogen spotlight, a pair of orange eyes glow like burning embers from a dark patch of weeds. Dr. Glenn moves closer, reaching delicately toward an object motionless in the water.
There is a drenching splash.
"Got him!" he exclaims, hoisting aboard a squirming alligator whose snapping jaws are wrapped quickly with duct tape.
The exercise is repeated more than a dozen times before daylight, mostly with small gators. The big ones, some exceeding 9 feet, are left alone.
"Too big to mess with tonight," Dr. Glenn says. "Another time."
The researchers from Savannah River Ecology Lab are studying the gators in Par Pond, which harbors one of the nation's largest inland populations of the once-endangered reptiles.
The 2,800-acre lake within Savannah River Site holds hundreds of gators and is off limits to the public - offering scientists an opportunity to study one of nature's most misunderstood creatures in an undisturbed habitat.
"What we do out here has several purposes," said Dr. Glenn, an assistant research scientist at the lab.
One objective is to determine how Par Pond's murky past as a cooling pond for two nuclear reactors has affected the environmental health of the creatures that now live there - including alligators.
"We're trying to look at the genetic impacts of contaminants on site," he said, noting that the sediment under Par Pond is slightly contaminated with radioactive material from the now-dormant reactors.
"We think it's unlikely we'll detect any effects here in the site," he said. "But we're going to develop the most powerful tests possible to ensure that's true."
The other objective - which has broad, national applications - involves devising a method to define genetic footprints in alligator populations.
The genetic compositions help characterize specific regions of known alligator populations, making it possible for authorities to determine the origin of a specific sample.
Par Pond gator DNA is compared with similar samples from gator populations in Louisiana, Florida and the South Carolina coast.
"Usually, with this kind of sampling, we can get within 20 miles of where a gator originates," Dr. Glenn said.
The methods being refined by this team will enable authorities who regulate the trade of alligator meat and hides to more easily determine where samples originated, which could help prosecute and discourage poachers.
For study purposes, each gator caught in Par Pond is weighed, marked with unique cuts on its back and tail fins - known as "scutes" - and punctured with a small needle to withdraw blood and DNA samples.
No one knows exactly how many gators reside in Par Pond, said Cub Stephens, an SREL wildlife technician who guides scientists on gator-getting expeditions.
"But for every one you see, there are several more you don't see," he said. "The medium sized ones stay in a general area. The big ones go anywhere they want to."
Caution, common sense and experience make gator-gathering easier than people think, said Mandy Dust, a graduate student at SREL who assists during nocturnal research adventures.
"I've done this a bunch of times, and I've still got all 10 of my fingers," she joked.
Besides their bite, alligators can swing their tails or heads and pack quite a wallop, Dr. Glenn said. "Getting hit with their head is like getting kicked by a horse."
Although Augusta is on the fringe of the giant reptile's domain, the creatures are increasingly common because of decades of protection and habitat conservation.
They are seen regularly in the Savannah River, Augusta Canal and the Merry Brickyard ponds, and a 9-foot specimen was captured just last week wandering across Gordon Highway near Molly Pond Road.
Alligators reached their low point in the Southeast in the 1960s because of unregulated harvest and poaching. The species was federally protected from the 1960s until 1987.
Reach Robert Pavey at (706) 868-1222, Ext. 119.
A 3-foot alligator weighs 4 pounds. But a 12-foot specimen weighs more than 500 pounds. Alligators longer than 9 feet are usually males.
An alligator's front feet have five toes, but rear feet have only four toes and are webbed. Females can lay 50 3-inch eggs that incubate nine weeks before hatching.
Georgia and South Carolina each have about 100,000 alligators, compared to 1 million in Florida.
Four alligator attacks have been documented in Georgia since 1992, and 25 attacks have been recorded in South Carolina since 1974. None were fatal. An alligator will kill someone every five to 10 years, usually in Florida.