The Argentine tegu lizard doesn’t grow nearly as big as a Burmese python but it may be a greater threat to South Florida’s native animals.
At a maximum size of four feet, a tegu can’t gobble down a full-grown deer or alligator with its rapier-sharp teeth. But the invasive, black and white reptiles have the potential to cause even more ecological damage than the 18-foot snakes that have drawn international media attention in recent years. And now, scientists say, it’s too late to eradicate them.
“When we first found out about them in 2008, we thought we had a chance to nip this population in the bud,” said the National Park Service’s Tony Pernas, who co-chairs the Everglades Cooperative Invasive Species Management Area group. “Now we’ve changed from eradication mode to containment mode.”
Long a popular staple of the exotic pet trade, the tegus likely were released by irresponsible owners or escaped from captive breeding facilities in south Miami-Dade County. Right now, the escapees’ epicenter is in the Florida City-Homestead area where federal, state and local agencies — with help from private trappers — are trying to round up as many as possible before the animals go into hibernation in October. Another distinct population has cropped up in west-central Florida’s Polk-Hillsborough county area.
The chief worry among scientists and wildlife managers is the tegus fanning out to neighboring Everglades National Park (where a handful have been captured) as well as east to FPL’s Turkey Point nuclear power plant and south to the Crocodile Lake National Wildlife Refuge in north Key Largo. Containment is urgent, they say, because the lizards will eat just about anything — small mammals, birds, insects, plants, and their all-time favorite — eggs. That means goodbye to the baby American crocodiles that would have hatched in the refuge and the sand berms of the power plant — and recently were downlisted from an endangered to a threatened species. It could also mean lights out for the endangered Key Largo wood rat — not to mention other native creatures.
“They have the potential to impact all kinds of listed species,” said Jenny Eckles, non-native wildlife biologist with the Florida Fish and Wildlife Conservation Commission. “Tegus can go through the water. They’re very adaptable to a number of different habitats, which is why we consider them to be problematic.”
Unlike Burmese pythons, whose numbers were knocked down by the extended cold period in early 2010, tegus thrive in temperatures as low as 35 degrees and as high as South Florida’s steamiest. Eckles and others tracking them say they often find tegus out in the open during the hottest time of day.
The animals hibernate in burrows from October until about January or February, then emerge once again to forage and reproduce. Females can lay 35 eggs a year.
Eckles and other scientists say they don’t know the size of the tegu population here or in west-central Florida. But their numbers definitely are on the rise. Pernas said trappers caught 13 in 2009. So far this summer, researchers from the FWC, National Park Service, ZooMiami, University of Florida, South Florida Water Management District, and U.S. Geological Survey have captured more than 140 — mainly from public lands — which were euthanized humanely, according to Eckles. She said citizen trappers have taken more than 300 from private lands with permission from landowners. Unlike with Burmese pythons, people do not need a special permit to trap and keep tegus. However, they must obtain a Class III license from the state to sell exotic wildlife.
Tegus are very difficult to catch by hand and are much easier to trap using eggs as bait, according to Jake Edwards, a wildlife technician hired by FWC to capture the lizards in South Florida.
On a recent hike checking traps in the Southern Glades Wildlife and Environmental Area, Edwards tried unsuccessfully to catch a couple of free-roaming tegus.
“You’re going to want to listen; you’ll hear it going through the brush,” he explained of his hunting methods. “It might be basking on the road. You might have about 10 seconds before it runs away.”
But neither Edwards, nor Jeff Fobb — a trapper who also heads Miami-Dade Fire Rescue’s Venom One unit — recommends grabbing a tegu by hand, due to its damaging teeth and claws.
“I’d rather get bit by a 10-foot snake than that guy right there,” Fobb said, pointing to a two-footer he recently caught in someone’s garage.
South Florida’s burgeoning tegu population has spawned something of a cottage industry: trappers who sell them as pets.
Rodney Irwin, 59, of Homestead — a former yacht captain and demolition worker — began trapping tegus on private land for fun and profit about two years ago.
He estimates he’s taken between 800 and 1,000, selling most of them directly to customers on his website, tegusonly.com for about $100 apiece. He also sells to a wholesaler for between $35 and $50.
Irwin says he’s working to benefit South Florida’s ecosystem.
“This is a chance for me to make a difference,” he said. “I can’t do anything about the apes in Borneo, but I can do something about the natives in my hometown.”
Asked whether he was concerned that the pets he sells may end up right back in the Everglades abandoned, Irwin responded that none of his customers are local and, in any case, they could buy a tegu in a pet store. He said he shares his capture data with the scientists working to contain the lizards’ spread.
So far, there are no plans to include tegus with Burmese pythons for restrictions on ownership, according to Kristen Sommers, who heads the FWC’s exotic species section. Instead, more study is in order.
“We need to figure out what’s going on with this,” Sommers said. “We’re still in an information-gathering mode, trying to figure out what’s the potential for spread and expansion and what would be the impact if that did happen. I hope within the next year we’ll have enough data to determine our next steps.”