But barely a decade ago, neither could scientists in Florida, where the invasive reptiles have established a breeding population that is expanding northward.
"Part of what we want to learn is how far north they could survive," said Dr. Willson, a postdoctoral research scientist at Savannah River Ecology Lab, where a yearlong study is under way to determine whether the giant snakes could spread to Georgia and South Carolina.
Burmese pythons, a staple of the pet trade for decades, can grow to 20 feet long and weigh more than 200 pounds. They have spread rapidly through south Florida, with population estimates in the tens of thousands.
"Nobody knows for sure how they got there, but the prevailing opinion is that they were knowingly or unknowingly introduced," Dr. Willson said.
Theories include pythons escaping from pet stores after Hurricane Andrew to a more likely case of owners simply releasing them.
"What we do know is that they are certainly reproducing and expanding their range," Dr. Willson said.
The fear is that they will continue to move north, but how far north remains open to debate.
A 2008 study by the U.S. Geologic Survey concluded most of the Southeast includes habitat that closely matches the python's native range in Asia. However, another scientific paper, published in the Bulletin of the Chicago Herpetological Society , argued against those conclusions, Dr. Willson said.
"That paper suggests that there is a genetic group of snakes in the Everglades that is probably a Burmese python subspecies that mainly stays in the tropics and could only live in south Florida, south Texas and maybe a few small areas of southern California," Dr. Willson said.
The experiment under way at Savannah River Site should help settle the argument.
"The purpose of the project here was to take snakes directly from Florida and bring them to SREL and expose them to our natural weather and climate," he said.
Seven snakes were brought in initially, and three more -- including a 13-footer that is the largest -- were released Saturday.
The studies will include monitoring types of habitats the pythons use during colder weather, their tolerance to cold and other factors that would determine their adaptability to new areas.
Dr. Willson said precautions are being taken to avoid escapes.
"We have a well-designed, snake-proof enclosure, and we've modified it quite a bit, with an eight-foot-high smooth wall set in 20-inch concrete, to accommodate these larger snakes," he said. "We're also using all-male snakes, so there's no chance they could reproduce."
As an additional line of defense, each python was implanted with a radio transmitter that will allow scientists to find them.
"This is important in the research because they are incredibly hard to find, even when they are right there in front of you," Dr. Willson said.
The size and appetite of the Burmese python makes it a dangerous addition to any environment.
Florida scientists have been catching and examining the snakes as fast as they can, and also collecting the growing numbers of pythons run over on roads. One standard part of the studies includes a checking to see what's in their stomachs.
"They've recorded virtually every warm-blooded species in southern Florida, including certainly rodents and raccoons, all the mid-size mammals, whitetail deer, bobcats, wading birds -- just about everything," Dr. Willson said.
The giant snakes are also known to attack and eat alligators, though there is still some debate over which is the superior predator.
"So far, from what they've found, the gators are winning about half those battles, but the snakes are winning the other half," Dr. Willson said.
The project is a joint effort that also involves the National Park Service, University of Florida and Davidson College. UGA professor emeritus Whit Gibbons and Davidson College professor Mike Dorcas are also involved in the studies.
SRS is the perfect backdrop for such an unusual experiment, Dr. Willson said.
"This is a study you couldn't do, for logistical reasons, anywhere else," he said. "Geographically, it is perfect, and we have the facilities and a long history of herpetological research."
Reach Rob Pavey at (706) 868-1222, ext. 119, or firstname.lastname@example.org.