After roughly six weeks of searching for the python that activated the alarm, research technicians located the 66-pound snake hiding underground. They needed about six hours to yank her out of the ground before they euthanized her. In her stomach, researchers discovered the collar — confirmation their plan worked.

Cove told The Washington Post that he hopes the experiment, which is ongoing in Key Largo thanks to a grant from the U.S. Fish and Wildlife Service, will protect endangered species and preserve ecosystems.

“There’s not really many things restricting [pythons’] population expansion,” said Cove, a research curator at the North Carolina Museum of Natural Sciences. “I’m still cautiously optimistic that if we can remove a bunch of these big females before they’re reproducing, that we could manage this invasive predator.”

Pythons originated in Southeast Asia, but they came to the United States in the 1970s and 1980s, often as pets. They soon started appearing in the Everglades after breaking loose or being dumped by their owners. The snakes, which can grow up to 18 feet long, are now linked to sharp declines in mammal populations in South Florida’s wetlands.

According to a ScienceDaily study, the number of raccoons, opossums and bobcats in the Everglades all dropped by at least 87 percent between 1997 and 2012. The same study found that marsh and cottontail rabbits and foxes had disappeared from the area.

In recent years, pythons have traveled south to Key Largo, where Cove said the first python was detected in 2007. Their migration left Key Largo woodrats and Key Largo cotton mice, which are endangered species, vulnerable to extinction.

“We haven’t seen the kind of massive declines in mammals that you see in the Everglades,” Cove said, “which suggests to me that we’re still early in the invasion” in the Florida Keys.

Cove said he wants to pinpoint the locations of female Burmese pythons, which eat more mammals than their male counterparts, across a 12-mile forested area.

Wildlife officials and researchers have tried other methods to hunt pythons, such as spying on them to study their movements and tracking them with dogs. A Florida agency holds an annual python catching competition, and in 2017, the state hired python hunters from India. In the past few years, researchers have used cameras to detect pythons.

Cove developed a new approach. He said he bought 30 GPS collars for about $1,000 apiece, then caught opossums and raccoons in the area and bolted a collar around their necks with a leather strap in late April. Cove said the collars don’t place animals in greater danger of being eaten.

Researchers programmed an alert to sound when the collars stop moving for more than four hours, Cove said. That could signal that a python consumed the collar-wearing mammal and was resting to digest.

Months passed without an alert until one sounded in mid-September. Because the snake had gone underground, for weeks they couldn’t locate it. But on Nov. 1, Cove said, a technician spotted it.

Once discovered, four people struggled to pull the 12-foot-long female python out of the ground by her tail. After researchers euthanized her, Cove said, an X-ray revealed the collar in her stomach. She had eaten one of the opossums.

“When you remove these big, reproductive, reactive females from the environment, you are simultaneously saving generations of animals,” said Kelly Crandall, a Southern Illinois University graduate student and researcher in the study. “Every animal has roles within their ecosystem. They’ve had this system in place for such a long time. And now all the players are being taken out.”

Researchers received another buzz on their radios in January. This time, a raccoon had been eaten, Cove said. Four people fought again for hours on Jan. 30 to control a 77-pound female python. After euthanizing the snake, they found another collar, according to Cove.

Last week, however, the researchers confronted an obstacle. Their radios buzzed, and they tracked down the GPS collar. It was sitting among a python’s feces, researchers said, likely because the snake had swallowed and digested the collar.

Forty other animals were outfitted with collars, but researchers have encountered other roadblocks, Cove said. Six of the animals have disappeared, and a few others were struck by cars, he said.

Still, they hope to get more alerts before pythons find new territories to dominate.

“The suitable habitat for the pythons is only going to expand,” Crandall said. “We are going to potentially be seeing pythons not just in Florida, but in Georgia, Alabama, Louisiana — even as far north as North Carolina.”