Huge, Hungry Tegu Lizards Invade the Everglades and Beyond

Florida has an invasive reptile problem, and it's not just the Burmese python.

Though it doesn't have its own Super Bowl or a Discovery Channel TV show dedicated to its hunters, the Argentine black and white tegu — a lizard that can grow to be the size of a large dog — is a major threat to Florida's ecosystem, and scientists say the threat is only getting worse.

Tegus were introduced to Florida and Miami-Dade County from their native South America via the exotic pet trade. The reptiles actually make good pets, according to Melissa Miller, invasive species research coordinator at the University of Florida's Institute of Food and Agricultural Sciences (IFAS). Tegus are intelligent and docile when raised from hatchlings, but the problem arises when they escape or get let out by their owners when they grow to their full size of four feet long. Once in the wild, they wreak havoc.

"They're omnivores, so they eat everything," Miller tells New Times. "They're eating a lot of native wildlife like gopher tortoises, and they steal eggs from alligator nests."
The mini Godzillas aren't as prevalent an invasive predator as the Burmese python, but Miller says they pose as great a threat as their legless cousins, and perhaps an even greater one. Because they like to snack on endangered and threatened species native to Everglades National Park, the invasive lizards are hampering Everglades restoration efforts, which already cost the state and federal governments billions of dollars.

"We're trying to restore the Everglades and get the hydrology right, and we want native animals there instead of invasive species like tegus and pythons," Miller explains.

This month, IFAS published a new fact sheet on Argentine black and white tegus, highlighting the "runaway train" of tegu and invasive reptile spread in Florida and beyond. (A PDF of the fact sheet is embedded at the end of this article).

According to the fact sheet, the number of tegus caught by IFAS and their partner agencies — the Florida Fish and Wildlife Commission (FWC), the National Park Service, and the U.S. Army Corps of Engineers — has steadily increased since 2012. In 2019, the last year for which tegu capture data is available, tegu numbers saw a huge spike, with a total of 1,452 tegus captured throughout the state, compared to 890 the previous year.

Miami-Dade County in particular is a hotbed for the cold-blooded egg snatchers, with over 4,000 tegu sightings reported through March 2020. While they don't like water and marshland, they thrive on tree islands in the Everglades and use manmade levees as "highways" to dart around the national park, according to Miller. They've also been found in debris piles on farmlands in the agricultural areas of Miami-Dade.

But the biggest issue of all with these encroaching critters is their ability to live in colder temperatures, which means they won't be contained to South Florida for long.

"In South America, they can live in more temperate, cooler climates, so they can survive as far north as Alabama. There's already an established population in Georgia," Miller warns. "That doesn't bode well for the rest of Florida."

Miller and IFAS hope the fact sheet is the first step in a "call to arms" against tegus in order to keep their population down. Tegus are still a step behind pythons on the "invasion curve," a graph that illustrates just how detrimental an invasive species population has become. Pythons are listed as stage four: long-term management, where complete eradication is impossible. Tegus, on the other hand, are still in the containment stage, where the population can be eliminated with sufficient effort, though it's getting harder by the year.

"Pythons are a very sexy story because it can get sensationalized and gets a lot of attention when people take pictures with large snakes, but I think more attention needs to be paid to the tegus," Miller says.

The hope is that with enough public support, legislators can put more financial resources into efforts to curb the tegu population and provide more legislative support for their removal. In April, Florida made it illegal to buy, sell, or possess tegus as pets after a new FWC ruling.

Miller says if landowners or civilians see tegus in the wild, they're allowed to capture and humanely kill the animals without a permit, as they are only protected by animal cruelty laws in Florida. Those a little more squeamish about harming them can call the invasive species hotline at 888-IVE-GOT1 (483-4681) to report a sighting, or use FWC's nonnative species app.

"The quicker we hear about them, the quicker we can get rid of them and deal with the drastic scope of the problem," Miller says.