The discovery of a radio transmitter from a studied Burmese python inside the stomach of a native cottonmouth snake has provided researchers with a rare piece of evidence in the ongoing conflict between invasive pythons and native wildlife in the Florida Everglades. A biologist tracking the signal from the implanted transmitter found a swollen cottonmouth in the saw grass containing the transmitter. An X-ray confirmed the python had been swallowed by the native snake. This event is one of several documented cases where native animals have preyed on pythons, a development that offers some insight into how the ecosystem is responding after two decades of python dominance.

Burmese pythons are not native to Florida. Their natural habitat is in Southeast Asia. They arrived in the United States largely through the exotic pet trade, with more than 180,000 imported between 1975 and 2018. When pet owners released snakes that had grown too large, combined with escapes from breeding facilities during Hurricane Andrew in 1992, a free-living population became established in South Florida. The climate and flooded landscape of the Everglades closely resembled their native habitat but lacked the predators and diseases that would normally control their population.

Without natural checks on their numbers, the python population expanded across more than a thousand square miles. They grow to significant sizes, with some reaching over 19 feet and weighing more than 200 pounds. Their presence has had a measurable impact on native mammal populations. Surveys conducted in 2012 and compared to earlier data showed that raccoon populations had declined by over 99 percent, with opossums and bobcats also suffering major losses. Marsh rabbits and foxes were no longer detected in the surveys.

For approximately 20 years, no native animal was documented as an effective predator of the python. The American alligator was considered the most likely candidate to challenge them. Encounters between alligators and pythons have occurred, with some alligators succeeding in killing smaller pythons. However, a 2015 finding of a dead python that had swallowed a six-foot alligator before its own stomach ruptured underscored the limitations of this natural competition. The alligator was viewed as capable of fighting a python to a draw, but not of controlling a species that produces up to 100 eggs per year.

The first evidence of native predation on python eggs was recorded in June 2021 in the Big Cypress Preserve. A research camera captured a bobcat entering the nest of a 14-foot female python and eating the eggs. The bobcat also swiped at the mother python when she returned. No predator had previously been documented preying on python eggs in Florida. Further evidence indicated that bobcats had killed and fed on adult pythons, including a 10-foot male.

The cottonmouth that swallowed the transmitter-tagged python demonstrated that predation was not limited to mammals. The cottonmouth, a native snake measuring 43 inches, had consumed a python nearly its own length. The eastern indigo snake, a federally protected species that hunts other snakes, has also been documented consuming young pythons. In May 2023, camera footage showed at least four vultures puncturing eggs in a python nest, marking the first documented case of a bird preying on python eggs in Florida. There have also been reports of a Florida black bear attacking a full-grown python.

These incidents indicate that a range of native species, including cats, snakes, birds, and bears, are now predating on pythons at various life stages, from eggs to adults. While this marks a shift from the previous understanding that no native animals could affect the python population, biologists have not concluded that these predators can control it. These attacks primarily target eggs, hatchlings, and smaller juveniles, while adult females continue to produce large clutches of eggs.

Additional factors complicate the picture. The spread of a tongueworm parasite carried by pythons has been found in the eastern indigo snake population, which may threaten the very species contributing to the predation pressure. The process by which native animals learn to identify pythons as prey is gradual and occurs through individual survival rather than across generations, with only those animals that successfully make the switch passing on these behaviors. The long-term outcome, whether native species can adapt quickly enough to reduce python numbers, remains an open question. The data so far shows a resistance that has begun to emerge, but it is not yet clear if it will be sufficient.