Even as parts of Florida brace for record low temperatures, it likely won’t be cold enough for long enough to kill large numbers of one of the state’s most troublesome invasive species, the Burmese python.
The snakes, most common in the Everglades, don’t fare well in the cold, but they have adapted to slither beneath heavy vegetation or go underground to stay warm enough to survive, said Ian Bartoszek, a wildlife biologist at the Conservancy of Southwest Florida.
"If they’re caught sort of exposed in a freeze event — this is a subtropical species so that can be lethal for sure," he said. A cold couple of days would hurt pythons "that aren’t adapted well" and don’t find warm shelter.
"But we need a real deep freeze to hit them back hard," Bartoszek said.
Bartoszek said biologists with his organization use radio transmitters and have tracked 20 pythons in the last week, with the snakes seeming to weather the drop in temperature well. Many have found shelter in armadillo or gopher tortoise burrows, he said, where temperatures can hold in the 60s even if it’s freezing at the surface.
Bartoszek said one python curled up several feet below ground in a gopher tortoise burrow this week, with the tortoise closer to the surface. That could mean the tortoise was in a colder position — yet another example of the invasive snakes affecting a state-protected species.
Everyone agrees that the pythons are bad for Florida. They likely took hold after residents released their pets into the Everglades. They are good at hiding and hunting, and have decimated populations of small animals, including raccoons, opossums and rabbits, and they may be spreading parasites to other snakes.
No one knows exactly how many pythons call south Florida home, though estimates are in the tens of thousands.
In their native range in southeast Asia, Bartoszek said, Burmese pythons use porcupine burrows to get out of the cold.
"They’re an intelligent species. They’re going to try to seek cover when they can," he said. "It’s natural selection. It’s the ones who have figured out what Florida’s habitat has to offer."
In the Everglades, where the soil isn’t always fit for burrowing, pythons also move into warm water or cracks and holes in the rocks along berms and levees, said Frank Mazzotti, a wildlife ecology professor at the University of Florida. Around this time of year, he said, they’re going underground to mate anyway.
The cold snap has hit North Florida hardest, Mazzotti said, sparing to some extent the points further south where most pythons live. Scientists still are not exactly sure what temperature is deadly for pythons, he said, or for how long they must be exposed before freezing.
But without sustained colder temperatures in the lower part of the state, he said, this frigid spell "is going to have a minimal impact."
Contact Zachary T. Sampson at [email protected] or (727) 893-8804. Follow @ZackSampson.