NewsFull Circle


Exotic Animal Invaders: Tracking the invasive Burmese python through the swamps of Florida

Stopping invasive pythons through advanced tracking
Burmese python at the Florida Aquarium.
Posted at 5:47 AM, Mar 17, 2022
and last updated 2022-03-22 15:01:18-04

EVERGLADES CITY, Fla. — Elusive and cryptic are all great adjectives to describe the invasive Burmese python. The apex predator, native to Southeast Asia, is now dominating and out-competing native species, and biologists are trekking into the python's new home to stop its spread.

ABC Action News reporter Michael Paluska and photojournalist Reed Moeller spent the day with National Park Service wildlife biologist Matthew McCollister. He tracked four tagged male snakes called "scout snakes" in Big Cypress National Preserve.


Burmese pythons are one of the longest snakes on Earth. If you are scared of snakes, the hike we took isn't for you.

We saw native cottonmouth along the trail and one of the pythons in a place where they shouldn't be. We hiked through tall grass, thick brush, and water up over our thighs, some areas waist-deep. The natural environment in Big Cypress is one of the wildest places you'll ever see. Another world is a short drive from major cities like Miami and Ft. Myers. Yes, the swamps are full of alligators, venomous snakes, bears, bobcats, and panthers. But, McCollister stresses that the likelihood of having a run-in with one of those is rare.

"What are the dangers out here you guys face? Other than giant snakes?" Paluska asked McCollister.

"The highway is super dangerous, U.S. 41, it is super dangerous," McCollister said. "Yeah, there are alligators, and there are venomous snakes, but those are typically very predictable. The odds of encountering a python in the field is low. You are more likely to see and capture a python crossing the road."

Heat exhaustion, getting lost, or spraining an ankle on the trail are more likely to happen than an encounter with one of Florida's top predators. And, as we saw firsthand, even the tagged scout snakes are hard to spot when they are mere inches away. It took a few seconds to focus on the snake camouflaged in the thick grass. But, there it was, slithering slowly away from the prying eyes of McCollister and his field team.

Nature gives little away for free, and McCollister's work tracking tagged snakes uncovers more questions than answers.

"All this is focusing on understanding what role they're playing here — understanding how they use the landscape. Ideally, our big focus is vital rates, focusing on reproduction and survival," McCollister said. "This population has a tremendous growth potential and is expanding at certain rates, but our efforts are insignificant compared to that, you know, the need to develop new tools to kind of come up with new options is pretty important."

On the agenda during our hike with McCollister, a wildlife biologist with the National Park Service, was a search to find four male scout snakes. See how they are doing and if they lead McCollister and his team to a breeding female.

"That animal could be following a female, that's moving from patch to patch," McCollister said. "Our odds of finding the snake that is right next to our snake is high. And as you get further out, as your search grid gets larger, your odds get smaller. You have to be lucky and good to make it payout."

Finding a big female is the payoff. But, following the men to the women happens just once a year during mating season. So, time is of the essence to find snakes with the potential to lay dozens of eggs, hatching more invasive species into the ecosystem.

"Having a transmitted male, or several transmitted males, and transmitted female can allow us hopefully over time to see how they're locating each other," McCollister said. "And, as a result, we've seen, you know, this little group of males, we've pulled two good females out of it in the past month."

"How many pythons are you tracking right now?" Paluska asked.

"Right now, our team is relatively small. I believe that we are about 12 or 13 males, which at times, we've been as high and as the low 20s," McCollister said. "But, we're building up our female roster, females are going to be — particularly breeding females — are going to be the category of the population that we most need to understand. Reproductive females are what drives a population dynamic."

He added, "They have a lot of potential; they have a lot of things going in their favor. And as a result, they're very prolific here. And you know, they're likely doing better here than in their native range. Once they get to a certain size class, they probably have, they likely have very high survival, you know, 150 pound Python is not likely to be taken by things."

As sensational as this exotic species is and terrifying for some. Wildlife biologists also stress that a dangerous interaction with a python is extremely rare.

"There have been no human deaths from wild-living Burmese pythons in Florida. So overall, the risk of attack is very low," according to a USGS article. However, they also added, "we cannot categorically rule out the possibility of a fatal attack."


Burmese pythons are decimating the native animal population.

According to the United States Geological Survey (USGS), "the most severe declines in native species have occurred in the remote southernmost regions of Everglades National Park, where pythons have been established the longest. For example, in a 2012 study, populations of raccoons had dropped 99.3%, opossums 98.9%, and bobcats 87.5% since 1997. In addition, Marsh rabbits, cottontail rabbits, and foxes effectively disappeared."

The evidence of their feasts is often found inside the stomachs of pythons.

"When we open up a large snake, anything over 100 pounds always has hooves in it," McCollister said. "There's very little that hasn't been found in a python gut."

Researchers at the University of Florida also teamed up with state and federal wildlife agencies to determine how much impact the snakes are having.


"We've collected about a 65-pound female, that if she had the signs of a non-lethal bear attack, you know, a set of canine punctures through the side with radiating claw scars," McCollister said. "There are some interesting interactions. In no way does that mean that that's happening in a significant way to shape the population, but there's a lot of interactions."

As biologists continue to study the vast Everglades ecosystem, they are coming up with images and videos of interactions that have never been seen or documented before.

In February, the USGS published a groundbreaking report in Ecology and Evolution showing the first-ever video of a bobcat eating invasive python eggs. Lead author Dr. Andrea Currylow with the U.S. Geological Survey said it is "the first documentation of any animal in Florida preying on python eggs, and the first evidence or description of such antagonistic interactions at a python nest."

When the python returns to the nest, a face-off ensues. At one point, the bobcat takes a swipe at the 14-foot snake. The brave cat finally leaves unharmed.


The Burmese python was first recorded in the Everglades in 1979. The invasive species came to Florida through the exotic pet trade. However, biologists say many snakes likely escaped or got too big for their owners and were released into the wild.

"We've received over 130,000 reports of nonnative fish and wildlife since the early 1900s. And a lot of those reports are primarily from the past 20 years or so. And it's a variety of taxa, everything from freshwater fish, reptiles, amphibians, and the like," Sarah Funck, the Nonnative Fish, and Wildlife Program Coordinator at the Florida Fish and Wildlife Conservation Commission (FWC) said. "Burmese python is one of the highest priority species that we have here in the state."

Pythons are a prohibited species in Florida.

"So what that means is that you can only possess Burmese pythons with a permit, and that's only for certain qualifying entities that are engaged in research, exhibition, public exhibition, or some eradication and control activities," Funck said.

Funck said around 120 invasive species are considered established and reproducing across the state.

Funck told Paluska the public plays a vital role in stopping the spread of invasive species by reporting sightings and not letting pets loose.

"I think the most important thing for the public to be aware of and to remember is, is the phrase 'don't let it loose.' You know, if you have a nonnative species in your possession, and you don't want it anymore, for whatever reason, the worst thing I think anyone could do is release it into the wild."

In 2006, FWC launched an Exotic Pet Amnesty Program. A program for people to turn in pets and exotic pets to officials, no questions asked. To date, a total of 6,554 animals have been turned in. The top three are turtles, lizards, and snakes.


One of the best places to see invasive species up close and personal is ZooTampa at Lowry Park.

A menace to pets everywhere is the cane toad. They are poisonous to most animals that bite or eat them, especially dogs.

PREVIOUS COVERAGE: FWC reminds pet owners of 'very poisonous' bufo toads

"Nothing really eats them. And so they grow really big. They eat a lot," Tyson Facto, the Supervisor of Hers and Aquatics at ZooTampa, said.

The reptile exhibit at the zoo houses other invasive species like the invasive lionfish.

"Because they are not recognized by the native fish, they just eat everything. So that fits in their mouth. So the lionfish will eat it."

According to the FWC, lionfish are "native to the Indo-Pacific and the Red Sea; lionfish can be found year-round in Florida waters and from North Carolina to South America, including the Gulf of Mexico. They can be found in almost all estuarine and marine habitat types and have been found in waters up to 1,000 feet deep."

Facto said the main goal and mission of the zoo is to educate visitors about native animals and nonnatives.

"I'm taking care of the animals. We work with animals here at the zoo that are almost extinct in the wild, some that are extinct in the wild. So having people see them here it's kind of almost too late. It's already happened in the wild," Facto said. "So, getting people to change their mind and do better for the earth and the wildlife, it's a pretty big deal."


As biologists work to learn more about pythons established across the Everglades, some evidence shows they are moving out of their current established range. According to the FWC, "recent data indicate that the population is expanding north and west. Individuals have been found in southwest Florida in Naples and near Lake Okeechobee. Python observations outside south and southwest Florida are likely escaped or released pets."

An online map to track sightings shows many snakes along the spine and coasts.

Several programs are showing positive results. But, how big of an impact they are having will take time to tell.

Since 2013, the Conservancy of Southwest Florida has removed more than 25,000 pounds of snakes. The snakes can grow to nearly 20 feet and weigh well over a hundred pounds. But, they don't get that big without eating a lot. So, each snake makes a meal out of native species.

In 2021, The Florida Python Challengenetted 223 snakes.

And, theSouth Florida Water Management District's Python Elimination Program has removed more than 7,200 snakes. The program pays per hour with a bonus added in for size.

McCollister said it's a team effort across all agencies like FWC, USGS, the Conservancy of Southwest Florida, the National Park Service, volunteers, and everyone in between.

The ground and aerial radio-tracking programs have proved successful, and new approaches to capturing pythons are in place.

In 2020 the FWC launched a new tool to help find invasive Burmese pythons in the Everglades ecosystem, their FWC new Detector Dog Team.

But, even with so many resources, understanding the snakes and trying to find the best way to remove them will take time.

"Nobody wants to hear that research is slow; it is," McCollister said. "But, doing a bunch of work without knowing what you're up against isn't the best idea, either. There won't be a silver bullet for this or any other invasive species that we're challenged by and end up having to you know, people have to invest careers and, and resources. And sometimes you have to catch a break on top of all that hard work."