Researchers using pheromones, trackers to trap invasive pythons
Luring animals by tapping into their sex drive is an age-old practice — deer hunters rattle antlers to bring in territorial bucks. Turkey hunters mimic a hen’s come-hither yelp. Now, researchers from the University of Florida are using a similar principle to track, study and eventually euthanize invasive Burmese pythons in the Everglades ecosystem, where they’ve laid waste to native wildlife.
The lure for the snakes is pheromones. Researchers use pythons captured by South Florida Water Management District and the Florida Fish and Wildlife Commission, surgically outfit them with radio trackers and release them back into the sawgrass prairie. From there, they let the snakes’ tongues, which they use to detect sex chemicals, do all the work.
During mating season, from December through February, the females release pheromones that lure in males. The snakes gather in breeding aggregations, and researchers can then catch them and humanely euthanize them.
Burmese pythons have had explosive population growth in South Florida, and have decimated ecosystems in South Florida for decades. Indigenous to southeast Asia, they likely slithered their way into the Everglades in the 1990s via the exotic pet trade.
They’ve thrived, establishing breeding populations as far south as Key Largo and as far north at the Loxahatchee National Wildlife Refuge in western Palm Beach County. The largest invasive python ever recorded in Florida was 18 feet long.
Melissa Miller, University of Florida project lead, and invasive species specialist, said that tracked females can pull in dozens of males over the course of several days, and when they do, she and her team take airboats to the location, slog into the marsh and search nearby, snagging randy males.
Tracked males can lead researchers to the big females, who can carry up to 100 eggs. Miller said they key in on tagged males once they make a beeline in a specific direction, as if they’ve picked up a pheromone
trail, or when more than one male heads to the same tree island, where females often nest.
In addition to the potential bonanza of pythons gathered in a small area, researchers also can learn a great deal of crucial information about the invasive snakes’ habits in South Florida.
Miller said that more than the other scout programs, this one layers on data and knowledge in addition to removal. “When we track the female, she’s going to give us data on how many eggs she produces, where she likes to nest, how many hatchlings survive. All of that can go into models to estimate python abundance.”
Being able to understand how they’re using the sawgrass marsh and tree islands, where the snakes have all but destroyed mammal populations, will help future snake hunters kill more effectively.
The study launched in November, and will run for five years. So far, the team has started tracking eight adult pythons, and the surgeries have not deterred their sex drive. They recently plucked two males who’d come to court a tagged female and are hoping for many more.
This is not Florida’s first “scout” project using tagged snakes to locate those of the opposite sex, said project lead Melissa Miller of the University of Florida, but it’s the first in the classic sawgrass environment, which comprises the bulk of the Everglades.
“By doing that we’re filling in a gap with the other scout programs. It’ll help us learn how these snakes are using the tree islands, the marsh, the levees. Eventually we’ll create a regional picture of python habitat use,” she said.
This program also hopes to pioneer drone use, depending on state regulations. “We’re itching to get out there,” she said. “It’s the prefect habitat to use a drone. It’s wide open.”
Currently, when they hone in on a snake, they have to use air boats to hike into the sawgrass. It’s slow going. The drones they hope to use can track 40 snakes at once, she said. “Drones will really increase the data that we’re able to get from these snakes. We’ll get more location points and visuals, and reduce the amount of resources needed for tracking.”
There’s also more innovation afoot to control the snakes. A fellow researcher is working on a
synthetic python sex pheromone, and recently, scientists in Key Largo were able to locate and kill two massive female pythons when the snakes ate possums and raccoons that were wearing GPS tracking collars. Wildlife officials hope to outfit dozens of mammals with collars and euthanize the larger snakes that eventually eat them.