In southwest Florida, biologists tracking Burmese pythons have found that some hatchlings are being eaten by native predators, including a species researchers did not initially expect. Radio-tagged pythons have been located inside the digestive tracts of Florida cottonmouths, confirming that at least one native snake is capable of preying on the invasive species.

The findings emerged from studies in Big Cypress National Preserve and nearby state forests, where researchers attach small radio transmitters to young pythons to monitor their movements and survival. The transmitters include a sensor that signals if a snake stops moving for 24 hours, which usually indicates death. Biologists then locate the signal and examine the scene to determine the cause.

In one case in August 2020, researchers in Picayune Strand State Forest followed a signal from a young female python to an adult cottonmouth basking in the grass. The python was not present, but the transmitter signal moved with the cottonmouth over the following days. The team captured the cottonmouth, and the transmitter later passed through its system, indicating the python had been consumed.

A similar case occurred in May 2021 in Big Cypress National Preserve. Researchers tracking a 39-inch female python found a 43-inch cottonmouth with a visible bulge. An X-ray at Zoo Miami showed the python’s spine inside the cottonmouth, along with the transmitter. The cottonmouth was released and later passed the transmitter naturally.

The Florida cottonmouth, also known as the water moccasin, typically ranges from two to four feet long and feeds on fish, frogs, birds, small mammals, and other snakes. It uses heat-sensing pits to locate warm prey, though pythons are cold-blooded, so cottonmouths likely find them by scent and movement. The species was recognized as distinct only in 2015, after years of taxonomic debate.

Researchers have also documented other native animals preying on pythons. A trail camera in Big Cypress in June 2021 captured a bobcat eating python eggs from a nest, the first recorded instance of a Florida predator consuming python eggs. In the same study, alligators accounted for several hatchling deaths, and birds of prey and cats were linked to others. An adult python was found killed by a black bear, and researchers have documented indigo snakes, black racers, and American crocodiles eating young pythons.

The findings come after years of concern about the python population’s impact on native wildlife. Burmese pythons, native to Southeast Asia, were introduced to Florida through the pet trade, with some owners releasing snakes that became too large to keep. Hurricanes in the 1990s may also have contributed to releases from damaged facilities. By around 2000, biologists confirmed wild breeding.

Road surveys in Everglades National Park between 2003 and 2011 found sharp declines in mammal populations, including raccoons, opossums, deer, and bobcats, with no rabbits recorded in some areas. A 2012 University of Florida study radio-tracked marsh rabbits and found pythons responsible for most deaths, confirming the snakes were a major factor.

Despite efforts to remove pythons, including state contractor programs and annual hunting challenges, the population has continued to spread north, with established colonies now reported in Charlotte County. Females can lay dozens of eggs per clutch, and many hatchlings die in their first year, but enough survive to sustain the population.

Researchers caution that native predators are unlikely to control the python population on their own. A study following 28 hatchling pythons over three years found that only about a third survived their first six months, with predation as the leading cause of death. Still, one clutch can produce several surviving adults, allowing the population to persist.

The documented predation events suggest that Florida’s ecosystems are beginning to respond to the invasion, though the long-term effects remain uncertain. Protecting native predators such as bobcats, indigo snakes, and cottonmouths may support ongoing removal efforts, but experts say human removal remains the most reliable tool for managing python numbers.