Invasive tegu lizards survive Florida cold and eat tortoise babies

The lizards have thrived for years in South Florida, but are colonizing as far north as St. Lucie County.
A tegu lizard belonging to the Florida Fish and Wildlife Conservation Commission is displayed during a press conference.
A tegu lizard belonging to the Florida Fish and Wildlife Conservation Commission is displayed during a press conference. [ Tampa Bay Times (2014) ]
Published Dec. 5, 2021

WEST PALM BEACH, Fla. — The Argentine black and white tegu is multiplying and mobilizing in the backwoods and backyards of the Sunshine State — a creature more ominous than pythons because of its cold hardiness and indiscriminate palate.

Wildlife officials have warned for years about the tegu’s expansion in South Florida’s amenable subtropical climate, but now the unusually brainy reptile is colonizing as far north as St. Lucie County with an appetite for everything from gopher tortoise babies to bananas.

This month, the Florida Fish and Wildlife Conservation Commission is meeting with federal officials, landowners and university researchers to discuss curtailing the St. Lucie population and getting ahead of the tegu problem overall.

But it’s a race they may already be losing.

In 2019, 1,425 tegus were removed from the wild — more than double the number trapped in 2015.

“It doesn’t seem like we’ve learned a lesson from our experience with pythons,” said University of Florida wildlife professor Frank Mazzotti, who leads the Croc Docs research team. “If you wait until you see the impact an animal is having, it’s too late.”

UF circulated an updated fact sheet on the tegu invasion in Florida this month, raising another red flag that “additional resources are critical to address the tegu problem on a larger scale.”

Released and escaped pets as well as unscrupulous dealers are responsible for seeding the tegu spread, Mazzotti said. One of his key concerns is the tegu’s appetite for eggs, whether it be sea turtle, crocodile, alligator, gopher tortoise or bird.

An analysis of the stomach content of 124 tegus included frogs, toads, lizards, snakes, turtles and small mammals. Threatened gopher tortoise hatchlings were found in the gut of five tegus from Central Florida.

Tegus will eat anything and everything

This is the first critter I’ve ever worked with that eats everything, truly everything,” Mazzotti said. “Because they can live in many more places and eat everything, there is not going to be a whole lot to stop them.”

Mazzotti said his research team was stunned in 2019 when it asked for community help identifying Nile monitor lizards in Palm Beach County and half of the photos that were sent in were of tegus.

The invasive species tracking website EDDMaps lists 43 tegu sightings in Palm Beach County back to 2009. The most recent report was made in May when a city of West Palm Beach employee found a tegu in the parking lot of Grassy Waters Preserve.

That’s compared to 6,008 reports in Miami-Dade County and 245 in Charlotte County. Both counties have known breeding populations.

Tegus have also been reported in four Georgia counties.

“Research and risk assessments conducted show that tegus have a high potential to become the next Burmese python in Florida,” said Larry Williams, Florida ecological services state supervisor for the U.S. Geological Survey.

Tegus have sharp teeth and can grow to 4.5 feet long

Tegus raised from hatchlings are considered household pets by some reptile fans. They can be housetrained and “like to be hugged,” Mazzotti said.

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They also have sharp teeth and claws and can grow to a length of 4.5 feet.

While there is no tegu management plan in Florida, FWC approved licensing changes in February that target 16 non-native reptiles, including tegus. The changes require tegu owners to have their animals microchipped with ownership information and registered through a free permitting process.

Also, beginning this past April, no new pet tegus can be acquired in Florida, but current pets can live with their owners until they die. Tegus cannot be imported into Florida, but are not listed federally as “injurious” wildlife, meaning they can be legally brought into other states where allowed.

It wasn’t until 2019 that state and federal officials began writing a python management plan. That was nearly two decades after pythons were first reported as having an established population in Everglades National Park. In 2012, U.S. Fish and Wildlife listed them as an injurious species, prohibiting importation and shipment.

A management plan outlines a species history, ecological and economic impacts, range, methods of control and how different agencies will work together.

Mazzotti said plans are valuable for getting all the agencies on the same page.

“It’s not that we don’t know what to do, it’s that we don’t have the resources,” he said. “We have to stop waiting for something terrible to happen for us to respond.”

By Kimberly Miller, The Palm Beach Post