Burmese pythons, native to Southeast Asia, have been established in the Florida Everglades since at least 2000, after arriving largely through the exotic pet trade and a suspected release during Hurricane Andrew in 1992. The snakes, which can grow longer than 18 feet and weigh more than 200 pounds, found an ideal habitat with abundant prey that had no natural defenses against them.

By 2012, researchers documented severe declines in mammal populations in python-occupied areas. Roadside surveys showed raccoons down 99.3% and opossums down 98.9% compared to pre-invasion counts. Marsh rabbits, cottontail rabbits, and foxes had disappeared entirely from the most heavily infested zones. Ground-nesting birds also experienced significant losses.

The difficulty of detecting pythons has complicated management. Studies indicate searchers find fewer than one out of every 100 pythons present in a given area, making reliable population estimates nearly impossible. In response, Florida launched paid removal programs, and since 2017, state contractors and participants in events like the Florida Python Challenge have removed more than 15,000 snakes.

That number, however, is believed to represent a fraction of the total population, which researchers say may number in the hundreds of thousands. One female python can lay up to 100 eggs in a single clutch, meaning removals have not kept pace with reproduction.

A more effective approach has involved radio-tracking male pythons to locate breeding females. These “scout snakes” have led researchers to some of the largest pythons ever captured, including 100-pound females carrying dozens of developing eggs.

Radio tracking also produced an unexpected finding. Tracked pythons began turning up dead in areas where they were thought to have no natural predators. Examination of the carcasses revealed wounds consistent with bites from cottonmouths, native venomous snakes that eat other serpents. The cottonmouths were envenomating pythons and leaving them uneaten.

Evidence also pointed to other native predators. Trail cameras and field observations documented bobcats killing and feeding on pythons. Large alligators, which young pythons had occasionally preyed upon, have been observed killing adult pythons in the shallows. Indigo snakes, large native snake-eaters, are also returning to areas where they had previously been displaced.

These native predators are contributing to python mortality, but researchers note that the overall balance has not yet shifted. The python population still outbreeds the pressure applied by its new predators.

Meanwhile, a lung parasite native to the python’s home range has moved into native snake populations, indicating that the ecological disruption may persist even if python numbers decline.