Invasive tegus are adaptable to cooler temperatures in the southern U.S./USGS

Tegu lizards, a large invasive reptile that has turned up in Everglades National Park in Florida, can adapt to temperatures cooler than the species tolerated in its native Argentina, according to U.S. Geological Survey studies.

"Several lines of evidence from recent USGS research studies published from 2018 to 2021 now provide clear indication for managers that the entire southeast portion of the United States is at risk of tegu establishment if lizard releases continue unabated," said Amy Yackel Adams, a USGS research ecologist.

The lizards are currently established in four locations in Florida and negatively impact native, ground-nesting animals in the Greater Everglades Ecosystem. The Argentine black and white tegu currently can be found in the counties of Charlotte, Hillsborough, Miami Dade and St. Lucie, according to USGS. Tegus are introduced to the U.S. through the pet trade and then likely released from captivity into the environment.

“Tegus are do-everything lizards,” Bryan Falk, the supervisory invasive species biologist at Everglades National Park, explained for a 2019 story. “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 dryer vent in someone’s house in Homestead. They will also eat almost everything, including small mammals, carrion, eggs, fruit, pet food, insects, and more.”

For the second study, published in PLoS ONE, researchers captured tegus in southern Florida and translocated them to a site in Auburn, Alabama, where they were housed in semi-natural outdoor enclosures for one year. Despite the fact that this region receives snowfall, most tegu lizards were able to survive the winter, grew rapidly and hibernated for longer periods compared to resident Florida tegu lizards. One lizard remained underground for a period of 244 days, representing the longest documented period of dormancy for this species. These findings support previous USGS climate studies predicting the lizard’s survival across much of the southern U.S.

Together, these studies demonstrate that tegu lizards can alter their hibernation behavior to match very different thermal environments, documenting the shortest and longest hibernation durations in this species.