Tegu lizards threaten native species around Riverview

The invasive lizards, which can reach five feet in length, are well established in east Hillsborough.
A tegu lizard belonging to the Florida Fish and Wildlife Conservation Commission is displayed during a press conference. Tampa Bay Times (2014)
A tegu lizard belonging to the Florida Fish and Wildlife Conservation Commission is displayed during a press conference. Tampa Bay Times (2014)
Published September 18

TAMPA — The Argentine black and white tegu lizard isn’t something you’re likely to forget if you see one in your yard, not only because of its vivid pattern but also because of its size; a full-grown tegu can stretch five feet from the tip of its snout to the tip of its tail.

The invasive species is well established in two Florida locations, the Homestead area of South Florida and the Riverview area of east Hillsborough County.

Though it has a mean bite if aggravated or cornered, it’s not venomous. But it joins a host of exotic reptiles, especially the Everglades’ Burmese pythons, that are wreaking havoc on the Florida ecosystem, said Todd Campbell, a University of Tampa biologist and expert on both the tegu and the monitor lizard, a three- to seven-foot long carnivore that has overrun the city of Cape Coral.

“We’ve got pythons, over 50 species of lizards, a couple of frogs — the Cuban tree frog, the greenhouse frog and the cane toad — so in terms of reptiles and amphibians, Florida is the most invaded area on earth that I know of,’’ Campbell said.

The tegu is an omnivore. It eats fruits, vegetables, dog and cat food, insects and small animals. But because it especially loves eggs, it’s devastating to turtles, alligators and ground-nesting birds. Of course, it will happily eat the live babies, too.

Muscular and up to five feet long, tegu lizards prey upon Florida's native wildlife, including some threatened species. [JIM DAMASKE   |   Times (2013)]
Muscular and up to five feet long, tegu lizards prey upon Florida's native wildlife, including some threatened species. [JIM DAMASKE | Times (2013)]

The tegus work the environment almost like a bear, Campbell said. “Think about a bear. They eat nuts and berries, they forage for food, and then if they’ve got a chance to get a mammal, to kill something, they will. They’re opportunistic that way.’’

The state’s biggest population is in extreme South Florida. “They are completely infested in there. They’ve caught hundreds of these animals,’’ Campbell said.

It’s harder to get a sense of how many are foraging around east Hillsborough County. The Florida Fish and Wildlife Conservation Commission has compiled reports of 307 tegu sightings, according to a spokeswoman, and have trapped and removed 128, but it has no estimate of how many are really out there. Captured lizards are euthanized.

Campbell thinks the Riverview population numbers in the thousands. He suspects they were well established there by the year 2000.

Tegus are South American lizards that feast on eggs and invade the burrows of endangered species such as the gopher tortoise. Associated Press
Tegus are South American lizards that feast on eggs and invade the burrows of endangered species such as the gopher tortoise. Associated Press

"It’s proven difficult to sort of manage them, figure out where we’re going to trap, find the little routes where we could trap them,’’ he said.

Researchers figure these invasive animal species get established in Florida after escaping from or being released by a pet owner or pet dealer. A sudden explosion of an invasive species population in an area indicates that a bunch were released at once, possibly by a dealer who has gone bankrupt and decided to set the inventory free, Campbell said.

In 2007, Campbell called on scientists to make a full-bore effort to save the state from invasive amphibians and reptiles.

University of Tampa biologist Todd Campbell holds a Nile monitor lizard. He is an expert on the monitor and the Argentine black and white tegu lizard, which has established itself in the countryside around Riverview. (Courtesy of Todd Campbell) Courtesy of Todd Campbell
University of Tampa biologist Todd Campbell holds a Nile monitor lizard. He is an expert on the monitor and the Argentine black and white tegu lizard, which has established itself in the countryside around Riverview. (Courtesy of Todd Campbell) Courtesy of Todd Campbell

"Amphibian and reptile introductions are reaching epidemic proportions in Florida, largely due to irresponsible behavior by pet owners and the pet industry, but also due to ineffective preventive policies and actions,'' he stated in a paper delivered at a symposium on managing vertebrate invasive species. "Prevention of additional amphibian and reptile introductions in Florida will require a comprehensive approach involving legal restrictions of certain problematic species, a massive public education effort, and a well-funded and staffed Early Detection and Rapid Response (EDRR) program.''

Campbell said he worries that if the invasive species aren’t eradicated, it could lead to eventually to what he calls “biotic homogenization.’’

He can imagine it happening around the world. "As we transport critters all around the planet, and those critters we transport cause the extinction of critters in those new locations, we’re just going to end up with one big globe of sameness. That’s a little dramatic, but you could make a logical leap to that end point: we’re going to end up with a couple of hundred species that are very, very dominant everywhere on earth.’’

------------------------------

To get a better grasp of the threat to the state and develop strategies to fight it, the Florida Fish and Wildlife Conservation Commission has set up a toll-free number for people to call if they see an invasive reptile or amphibian – 1-888-IVE-GOT1 (888-483-4681). From those reports, scientists can determine the size of the problem in a given area.


Advertisement