USA TODAY International Edition
UNTANGLING EVERGLADES
‘Judas snakes’ help cull invading pythons
Charlie 5 had no plans to move that hot morning. The 9-foot-long Burmese python was comfortably nestled in a muddy hollow, well hidden in a thicket of saw grass and alligator flag in Big Cypress National Preserve. His tracking device gave him away. He didn’t like it, but he had visitors. “There he is,” said Austin Fitzgerald, a biological science technician with the U.S. Geological Survey (USGS), bending down within 18 inches of the steamy muck. “I can just barely see his head.”
Using two snake hooks, Fitzgerald and Jillian Josimovich, a biologist with the USGS invasive species science branch, persuaded the reluctant snake to come out of hiding.
It’s hard to read a snake’s body language, but Charlie 5 – writhing to free himself – clearly wished he had never met Fitzgerald and Josimovich.
The uninvited denizens of South Florida’s wildlands, woodlands, marshlands and swamplands have left an indelible – and possibly irreversible – mark on the ecosystem.
First identified in Everglades National Park in 2000, the Southeast Asian apex predator quickly put a stranglehold on Florida’s wildlife.
To a python, Florida’s rich biodiversity of mammals, birds, reptiles and amphibians is a veritable smorgasbord of delicacies. According to the USGS, a study in Everglades National Park in 2012 revealed pythons have contributed to these population declines: 99.3% fewer raccoons.
98.9% fewer opossums.
87.5% fewer bobcats.
Foxes and marsh and cottontail rabbits have “effectively disappeared,” the study says.
As pythons eat their way across the Sunshine State’s landscape, there is strong evidence Florida’s bird, native snake and alligator populations also suffer.
What predators the python doesn’t eat lose the competition for food, including bobcats and panthers. The hunters are simply too large and too efficient. They are at home in warm, wet, watery climates and can swim, burrow and climb trees.
About the only thing they can’t do is fly. Researchers said pythons have swum across the open saltwater of Florida Bay from the Everglades to islands in the Florida Keys.
A fundamental problem in keeping up with the python’s assault on Florida is the snake’s ability to remain out of sight, said Matthew McCollister, a resource manager
with the National Park Service based at Big Cypress National Preserve in Ochopee.
The key is finding and removing breeding females, he said.
A clever approach underway in southwest Florida since 2013 helps scientists keep tabs on snakes. The Conservancy of Southwest Florida has worked with various groups – the USGS, National Park Service, James Madison University, zoos in Naples and Miami and Florida’s Fish and Wildlife Conservation Commission – to develop and assess ways to curb pythons’ proliferation.
When males are discovered crossing a road or slithering along a canal dike, they are caught and taken to a Zoo Miami lab where veterinarian Frank Ridgely, donating his time and facilities, surgically inserts a radio transmitter.
The pythons are released back into the wild to act as spies, hence their nickname “Judas snakes.” During the breeding season, which is December through April, the males lead researchers to the females.
“The radio transmitter allows you to follow it wherever it goes,” Josimovich said. “It emits a pulsating beep. We can go to our animal and potentially remove several other individuals” found in breeding populations called “breeding balls.”
Breeding balls sometimes have five or six males in close proximity preparing to mate with a single female.
In the past two seasons, the Judas snake method has enabled Big Cypress staff to remove 17 pythons – out of tens of thousands. One was the largest ever captured there: a 17.5-foot, 141-pound female bearing 73 developing eggs.
In the past six years, the Conservancy and its partners have cleared more than 500 pythons from a 55-square-mile area in Collier County.
Big Cypress’ vastness works against them. The preserve spreads across 729,000 acres, larger than Rhode Island. Not only are the pythons scattered far and wide, they’ve dug in to hard-toreach places.
Finding them often requires a difficult, lengthy hike in high heat under a blazing sun, sometimes walking through swamp water, dealing with mosquitoes and challenging weather. Some places are simply too remote for field staff to reach.
“The Everglades is very difficult to get into, and so is Big Cypress,” McCollister said. “You can’t go check on every snake using a helicopter. You can’t attract them. It’s really challenging.”
Charlie 5’s inconspicuous spot was somewhere on Windmill Prairie, about 8 miles north of Monument Lake Campground – more than a mile’s hike through thick underbrush.
By summer’s end, that spot will be under 2 feet of standing water, the heat will be insufferable and the mosquitoes will be thick enough to choke a cow.
The promising Judas snake program is worth the effort, McCollister said. “We have learned a lot from them while locating breeding events,” he said. “We started the season with only six animals and have grown it to 13, while removing six females.”
The snakes are “humanely euthanized,” he said.