At first, you could only find them in Miami.
Now, they scamper across Pinellas County park roads, delighting — or sometimes spooking — tourists. They swim in retention ponds beside Palm Harbor hospice centers, hide in backyard brambles behind Seminole Heights homes and sun themselves on sailboat decks overlooking Clearwater Harbor.
Green iguanas are invasive to Florida, and they love its tropical weather and coastal landscape.
Brought to South Florida from Central and South America in the pet trade during the 1960s, the reptiles have since migrated as far north as Lee and Collier counties. Cold snaps typically keep them from gaining any more latitude, experts say. But more than 300 sightings have been reported in the Tampa Bay area over the past decade, according to state wildlife data.
Warmer temperatures driven by human-caused climate change are pushing some of Florida’s migratory species north, like snook, roseate spoonbills and mangrove box jellyfish. It’s possible that climate change could expand the range of cold-blooded green iguanas up the state, said Sean Doody, a University of South Florida professor and conservation biologist.
But that won’t happen anytime soon.
“The climate is warming, but that’s kind of a slowish process,” Doody said. “They’re never going to, in our lifetime, become a problem in Tampa. But longer than that, if the climate keeps warming, they’re going to inch their way northward.”
It’s already happened in Fort Myers, where populations have been “exploding” in recent years, Doody said. The reptiles prefer the milder coastal temperatures found in South and Southwest Florida.
“What we can have is a bunch of mild winters, and then they’ll build up numbers, and they’ll inch northward. I’ve got a few reports of Fort DeSoto and all the way up to St. Pete,” he said. “Inland, they’re in a bit more trouble because they’re not buffered (from the cold) by the water.”
Iguanas spotted in Tampa and Hillsborough County are likely escaped pets, rather than members of a full-blown breeding population, Doody said. But it’s unclear whether iguanas in southern Pinellas County are breeding a sustained population there.
The cold-blooded creatures can’t regulate their body temperatures and become cold-stunned when temperatures drop near freezing. The cold doesn’t kill them, but sometimes it causes the reptiles to fall from their treetop perches.
It’s possible the reptiles could adapt to Central Florida’s cold snaps, extending their survivability, Doody said. The iguanas are known to submerge underwater and burrow underground when temperatures drop.
“We have a shortage of research into this,” Doody said. “All those ones that are being seen in Pinellas County, Fort DeSoto and all that: Are they physically dispersing there along the coast from Fort Myers? If we had some time and not that much money, we could clarify some of those things.”
Anna Yu, a park ranger at Fort DeSoto, is also unsure whether park iguanas are reproducing, but she remembers seeing one female that had been struck by a car. The dead iguana was filled with eggs.
“That could be an indicator that they were, at one point, potentially breeding out here,” Yu said. “We just truly don’t know.”
Yu has spotted about a dozen iguanas since she started working at the park five years ago. They’re skittish and go mostly unnoticed by park guests.
“When visitors see them, they don’t understand that it’s an iguana,” she said. “There’s probably a lot of sightings that go unreported to us because people just either assume that we know we have iguanas or they just don’t know that it’s an invasive species that they should be reporting.”
There have not been enough iguana sightings in Pinellas County to warrant removal efforts, a county spokesperson said. If the county ever did need to remove the reptiles, it would work with the state’s wildlife agency, the Florida Fish and Wildlife Conservation Commission.
The agency recently relaxed its rules to make it easier to sell live iguanas out of state and to encourage people to remove them from the wild. Residents are allowed to kill iguanas on their property and on 32 public lands in South Florida.
Doody, the USF researcher, called the state’s aggressive efforts to eradicate iguanas inhumane and futile.
“The state government and Miami, et cetera, have gone on a crusade allowing people to shoot them,” he said. “There’s always iguana killing going on, which is unfortunate because there’s so many of them, you can’t really control them.”
Doody said they are a pest to homeowners more than they are a threat to native species here. Florida has no native iguanas, and green iguanas have filled a niche in the ecosystem that does not require they outcompete other species, he said.
Instead, the giant lizards eat lawns and dig holes.
“One neighbor is going to like them, one neighbor is going to hate them, and the next neighbor doesn’t care,” Doody said.
Roland Hansen spotted one from his fourth-floor condo in Clearwater in 2019. The iguana, lazing dockside at the Island Way marina, reminded him of his own pet iguana named Fish. Hansen sold Fish years ago when she outgrew her 6-foot-tall pen, but he said he still has a soft spot for the critters.
“They’re sweet little animals,” Hansen said. “She was a vegetarian.”
Jake Streets, who goes birding nearly every day, reported a 2-foot iguana at John S. Taylor Park in Clearwater about three years ago. He snapped a photo with the high-end camera he normally aims at warblers and shorebirds.
“It’s just another nest predator preying on native bird eggs,” he said. “Other than that, I think if they start breeding and taking over, then they make a mess. They just crap all over everything.”
How to report a green iguana
The Florida Fish and Wildlife Conservation Commission maintains an invasive species hotline at 888-483-4681.
You can also report a sighting online at the agency’s website by submitting a photo of the animal, the location it was seen and the date.
This story was originally published in the Tampa Bay Times and shared in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the Sun-Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.
