Florida biologists prove invasive Burmese pythons are swallowing deer, alligators whole

The scale at which the Burmese python is able to decimate the native wildlife population in South Florida continues to astonish biologists studying to eradicate the invasive species.

Researchers in the region recently proved that Burmese pythons are able to stretch their jaws wide enough to swallow large prey -- such as fully grown deer and alligators -- whole, according to a paper published in the journal Reptiles & Amphibians.

"Knowing the size of prey that predators can consume facilitates understanding and predicting their ecological impact," the paper states.

A group of biologists stumbled upon a nearly 15-foot female Burmese python in December 2022 in the midst of devouring an adult white-tailed deer, Ian Bartoszek, a wildlife biologist and science coordinator at the Conservancy of Southwest Florida in Naples, told ABC News.

Bartoszek and his team use radio telemetry -- a technique that uses radio signals to track the movement and behavior of animals -- to understand the pythons' behavior. Trackers placed on males help researchers find the reproductive females, Bartoszek said.

By the time they got to the scene, the python had swallowed about half of the deer, and it took about 30 more minutes for it to consume the other half, Bartoszek said. Had the deer still been alive, the scientists would have intervened. Instead, they got a front-row seat to the intricacies of the food chain.

"For us biologists, this was the most intense thing we've ever seen on assignment," Bartoszek said. "This was as primal as it gets."

The female python weighed about 115 pounds, while the deer weighed about 77 pounds -- representing 93% of the snake's maximal gape area, the size of their mouth opening, according to the paper.

Burmese pythons can consume meals equivalent to 100% of their body mass, according to the Florida Fish and Wildlife Commission. While parts of white-tailed deer had been found in python necropsies before, this was the first time biologists had witnessed it in the wild, Bartoszek said.

"In this specific example, it feels like we caught the serial killer in action," Bartoszek said.

The large nonvenomous constrictor captures its prey by ambushing it before coiling around it. The snake then squeezes until the animal goes into cardiac arrest, Bartoszek said.

In the case they witnessed, the python had bitten the deer in the neck before coiling around it, he added.

"When you see their anatomy firsthand, they are amazingly designed," Bartoszek said. "Mother Nature did a very good job with the species."

Had that python lived, it probably would have "used" the feed from the deer over the course of a week, Bartoszek said. But since they are opportunistic hunters, the snake could have very well captured its next prey before then, he added.

A variety of species have been found in the gut contents of Burmese pythons during necropsies, including mammals, birds, reptiles, as well as federally protected species such as the wood stork and the Key Largo woodrat, according to the FWC.

Burmese pythons are one of the most concerning invasive species in the region, according to the U.S. Geological Survey (USGS).

The species, native to Africa, Asia and Australia, established a breeding population in South Florida through intentional and accidental release, according to the USGS.

Severe declines in mammal populations throughout Everglades National Park have been linked to the species, according to the USGS. A 2012 study found that populations of raccoons had declined 99.3%, opossum populations declined 98.9%, and bobcats 87.5% since 1997. Other mammals have "effectively disappeared" over time, such as marsh rabbits, cottontail rabbits and foxes, according to the USGS.

"Imagine just thousands and thousands of pythons eating their way through the Everglades," Bartoszek said.

Burmese pythons were added to Florida's Prohibited Nonnative Species List in 2021. The state also pays bounty hunters to catch Burmese pythons through the FWC's Python Patrol program.

The species, with its efficient reproductive capabilities and voracious appetite, is creating a cascading effect of loss within the ecosystem of the Everglades and surrounding areas, Bartoszek said.

"We didn't want to alarm people," Bartoszek. "We just want to showcase what our native wildlife is up against across the greater Everglades ecosystem."