Fears grow over invasion of ‘unusually brainy’ dog-sized lizards ‘that eat everything in sight’

The invasion of a dog-sized lizard species has sparked concern as it wreaks havoc on ecosystems in the south.

Central to experts’ fears is the fact that the roughly five-foot-long Argentine black-and-white tegu “eats absolutely everything,” University of Florida wildlife professor Frank Mazzotti told me. The Palm Beach Post.

They devour quail, chickens, turtles and even alligator eggs, as well as turkeys, ground turtles and ground-nesting birds. They also feast on gopher fruits, vegetables, plants and pet food.

This insatiable hunger threatens native wildlife, and now the beast has spread to more states, including Florida, Texas, Georgia, South Carolina and even Maryland.

“Because they can live in many more places and eat anything, there won’t be much to stop them,” Mazzotti warned.

It’s not known exactly how many of these highly intelligent creatures are currently in the United States, but there have been nearly 10,000 sightings since 2002, according to a database created by the University of Georgia’s Center of Invasive Species and Ecosystem Health.

The vast majority of reports occurred in Florida, particularly in the Southern Glades Wildlife and Environmental Area, south of Miami. There was one sighting in Maryland and five in Texas.

Although the Southern Glades Wildlife Park appears to be their main hangout, they have also been spotted in Miami itself and even in the posh city of West Palm Beach, where a resident found the lizard in a parking lot.

And as Mazzotti and others have noted, tegus can thrive in a variety of different environments, making controlling their numbers virtually impossible.

In 2019, Bryan Falk, then the supervisory invasive species biologist at Everglades National Park, called them “do-anything lizards.’

‘They are happy in many different environments, whether that is a natural or disturbed habitat. We once had a report of a tegu living in a drying closet in someone’s house in Homestead,” said Falk, who is now a program analyst for the National Invasive Species Council, an agency within the U.S. Department of the Interior.

Another reason why tegus have been able to migrate so far north is because they can maintain their body temperature during different seasons.

This discovery was created in 2016 by a group of Brazilian and Canadian biologists at São Paulo State University, and scientists have since considered the tegu the only warm-blooded lizard on Earth.

All other reptiles are strictly cold-blooded, meaning they cannot generate body heat or maintain their metabolism without being in a warm environment.

That’s why, when temperatures drop, alligators and snakes migrate to warmer places or hibernate to conserve energy.

Tegus do not have the same limitation, evidenced by the fact that they can raise their body temperature up to 10 degrees Celsius above ambient during their mating season in spring.

The extreme threat tegus pose to local wildlife comes at a time when Burmese pythons are also rolling through Florida.

Like tegus, Burmese pythons are an invasive species. However, pythons average 16 feet in length and can devour foxes, bobcats, raccoons, and other animals.

A recent study by the Conservancy of Southwest Florida discovered that pythons can also produce whole deer and certain alligators.

It is believed that both pythons and tegus arrived in the US through the exotic pet trade, with pythons being exported in the early 1980s.

Tegus only began spreading in earnest in the wild fifteen years ago, so experts believe its introduction occurred later.

Some measures have been taken by state authorities to limit tegu populations, including banning residents from keeping them as pets.

Florida and South Carolina banned the reptiles as pets in spring 2021, while Georgia banned any tegus not registered with the Department of Natural Resources by December 4, 2023.

All three states have grandfather clauses for current owners, and based on Tegus’ lifespan of about 20 years, they will likely remain in captivity for a while.

But when it comes to monitoring tegus that have escaped captivity or were born in the wild, scientists now believe they have discovered a much more reliable way to track them. And it has to do with DNA.

Environmental DNA (eDNA), which is continuously secreted by all living organisms, can now be detected more accurately than ever before.

New technology known as a tetraplex digital PCR test was developed by researchers at the University of Florida and can successfully detect the eDNA of four different species in a single water or soil sample.

University of Florida invasion ecology specialist Melissa Miller, the lead author of the studytold the South Florida Sun Sentinel that her team was able to see Burmese python DNA in a soil sample two weeks after the snake was removed from an outdoor enclosure.

This breakthrough was developed in the hope that if the technology were successful, it could be used to effectively monitor Florida’s more than 500 non-native species, including tegus.

Miller said eDNA testing will provide wildlife officials concerned with removing invasive species a cost-effective way to ensure they are indeed gone, rather than having to periodically monitor large swathes of land for physical sightings.