After twelve years of tracking and hunting Burmese pythons in South Florida, it takes a lot to piss off Ian Bartoszek. A wildlife biologist and the science coordinator for the Conservancy of Southwest FloridaBartoszek would say the same about Ian Easterling, his right-hand man and fellow biologist on the project.
“So when Ian started screaming with excitement, I knew something was up,” Bartoszek says Outdoor living about the encounter they had with a python on December 19, 2022 – an encounter that is the centerpiece of a new study and confirms how destructive these invasive snakes can be to native wildlife.
It was the middle of python breeding season and a typical day for the snake removal team, which focuses on a region near Naples that Bartoszek calls the Western Everglades. They used telemetry equipment to track one of their male scout snakes, Ronan, in the hope that this would lead them to a large breeding female, which is their main target for removal. The team discovered that and more when they approached the exploration tube and fell down an embankment into a drained retention pond.
“We turned the corner and Ian shouts, ‘She’s got… she’s got a DEER!’
Bartoszek says what they saw next was the most intense thing he has ever seen in the field.
“We see this large female python, and she’s about halfway through swallowing a large white-tailed deer,” said Bartoszek, who hunkered down with Easterling and their two interns to watch and photograph the ordeal. “Once it realized we weren’t a threat, [the snake] proceeded to finish his meal. And it’s hard to describe unless you’ve seen it with your own eyes, but this was as real and primal as it gets… We saw it swallow this animal right up to the tips of its hooves and swallow it whole swallowed.’
For Bartoszek, the sight was both shocking and affirming. Shocking because he says no Florida scientist has ever recorded a python swallowing a large white-tailed deer. However, he has suspected for years that this type of predation is widespread in South Florida, and his team has found evidence that pythons ate smaller deer in the past. (There is also ample evidence that pythons eat large deer throughout their native range in Africa, Asia and Australia.)
“For me personally, I’ve been beating this snake drum for over a decade now and telling people, ‘Hey, this is something. They are eating our deer on a large scale,” says Bartoszek. “A lot of those people took a while to catch up. But this is what we see in real time.”
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About ten years ago, Bartoszek and his team caught a 31-and-a-half-pound Burmese python, which regurgitated a 35-pound whitetail. A follow-up study found that this was the largest prey to python size ratio ever recorded for the Burmese python. And in July 2022, they found hoof cores and hair from an already eaten deer in the belly of a 215-pound snake, which remains the largest Burmese python (by weight) ever captured in the Sunshine State. The December discovery was different, however, because it was a full-size deer and the researchers were able to witness the swallowing process in person. Bartoszek says it took about 30 minutes for the snake to get the back half of the deer’s body into its esophagus.
“The other intense thing was how the snake positioned itself, and how the back part of its coil near the tail was corkscrewed,” Bartoszek explains. “He grabbed the deer’s hind legs and used that rear part of his body to feed the deer into his open mouth. They are impressive animals.”
After the deer was completely swallowed, he and Easterling held the snake and pressed on it until it vomited its meal, making it easier to carry the snake out of the field. They later weighed the buck at 77 pounds. (South Florida whitetails tend to be smaller than in other places, Bartoszek says.) The female python, meanwhile, weighed about 100 pounds and was just under 15 feet long.
“This just reinforces what we know,” says Bartoszek. “And if anyone is wondering what these animals are doing in South Florida, they are clearly eating their way through the Everglades food web. And that includes white-tailed deer.”
Squeezing the science out
In addition to producing some of the wildest photos ever taken of a Burmese python in Florida, the meeting was an opportunity for Bartoszek’s team to contribute to the growing body of research on the species. After euthanizing the python and taking it back to the lab, Bartoszek called Dr. Bruce Jayne of the University of Cincinnati, who has researched the maximum opening of a variety of snake species: the maximum diameter a snake is able to open its mouth due to its disconnected jawbones and flexible skin.
“He [Dr. Jayne] was the first person to see those photos and videos, and he was blown away,” said Bartoszek, who kept the snake’s head and part of its neck frozen in a block of ice. “When he came down about a month later, we had that snake, along with two other very large snakes that came from the Big Cypress area. One of them was the 20-foot snake those young boys gifted us, the longest python ever recorded in Florida.”
Using custom-made plastic probes in increasingly larger sizes, Dr. Jayne increasingly probes into the mouths of the three giant pythons. He continuously measured the size of a snake’s opening until the probe no longer fit (or caused tissue damage), and that final measurement would represent the python’s maximum opening.
Jayne found that all three snakes had a maximum gape diameter of 26cm, and the results were published in the peer-reviewed scientific journal Reptiles and amphibians in August. This number is significant, Bartoszek explains, because the previously recorded maximum cleft diameter for Burmese pythons was 22 cm.
‘And we don’t know. Some of these snakes can exceed that [26 cm]that is exactly what we were able to measure. So now we have a new benchmark,” says Bartoszek. “But if there’s one thing I’ve learned from studying these snakes, it’s not to underestimate the Burmese python.”
What this new benchmark means for Florida wildlife
By better understanding the limits of what a Burmese python can fit in its mouth, Bartoszek and other python researchers can better predict the ecological impact the invasive snakes will have as they spread into new areas. And the more closely they look at those consequences, the more serious Florida’s python problem appears.
For example, Florida researchers had heard claims years ago about the decimation of meso-mammals, medium-sized critters such as raccoons, rabbits and opossums.
“Well, a respected researcher thought that was far-fetched, so he took a bunch of swamp rabbits, collared them and released them into the core area of the Everglades,” says Bartoszek. “Within six months, 77 percent of those rabbits were found in the bellies of pythons. And then he became a believer.”
Bartoszek thinks the same could be going on with white-tailed deer, but he says there has been no definitive research on collared deer use in the core python range of the Everglades. He hypothesizes that if someone were to conduct such a study, “a lot of those collars would turn up in a python.” He also reiterates that previous discoveries of fawns and smaller deer in other, smaller pythons prove that the snakes learn to hunt whitetails from an early age.
This is concerning for local deer populations, which are currently declining in both the southern portion of Big Cypress National Preserve and Everglades National Park, according to the Florida Fish and Wildlife Conservation Commission. Both the reserve and national park are within the core range for Burmese pythons in the state. It is also concerning from a broader ecological perspective, as white-tailed deer are the main prey of the endangered Florida panther.
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All of this underlines the importance of the removal work that Bartoszek and other python hunters are doing. To give a rough estimate of that work, Bartoszek’s team alone has removed about 36,000 pounds (or 18 tons) of python from the Florida landscape, and they’re getting better at using male scout snakes to remove the large female find and remove breeding snakes. But Bartoszek says part of the challenge in eradicating Burmese pythons is constantly having to adjust what you think you know about them.
“Our native wildlife didn’t evolve with a large predator snake in the equation, and they don’t have the situational awareness of how to deal with that, so they’re vulnerable,” Bartoszek says. “Well, there is a similar parallel in the physical sciences. Where, if you haven’t seen this yourself, or seen evidence through shared images like this, you would be hard-pressed to think that this animal is capable of something like this.”
Dac Collins