South American invaders try to gain a foothold in the Everglades

EVERGLADES NATIONAL PARK __ Chicken eggs are pretty good, but alligator and crocodile eggs, sea turtle eggs and even bird eggs are also on the menu for the black and white Argentine tegus, a lizard that arrived in Florida by the pet store. trade and threatens, along with other plant and animal species, to disrupt the ecosystems of Everglades National Park.

Although probably not as destructive as Burmese pythons, another creepy invader in the park, tegus (Tay’goo) can reach 4 or 5 feet in length, rob ground nests of their eggs, and quickly generate a population boom that challenges efforts to drive them from the Everglades.

“They can weigh up to 10 pounds,” said Kevin Donmoyer, an invasive species biologist at the national park. “The size of a small dog. Tegus in captivity, there’s a lot of material on the internet with large tegus walking around people’s homes, hanging out with the dogs.”

For the past year, the National Parks Traveler writers and editors have chronicled problems across the national park system with invasive species of animals, plants, fish, and even insects. Our final stop was in April at Everglades National Park, arguably the park system’s poster boy for invaders. As we have noted, while much work and billions of dollars have been spent to restore the natural flow of the “grass river” from Lake Okeechobee to Florida Bay, a rejuvenation that stands to reap huge benefits to the park’s flora and fauna, on -the ground battles continue against invasive predators that have robbed the park of its small mammals and non-native vegetation that has overwhelmed parts of the fascinating sawdust prairie .

About eight hundred tegus have been captured since park staff began capture operations/Kim O'Connell

About eight hundred tegus have been captured since park staff began capture operations/Kim O’Connell

Pythons, which can reach over 17 feet and 160 pounds and are blamed for a staggering reduction – up to 99% in some cases — populations of small mammals native to the park, were first documented there in the fall of 1979. Today, thousands of large snakes are believed to be found in the park despite continuous efforts to catch them.

One battle the park hopes to have the upper hand involves Tegus. These stocky, low-lying black and white tegus (Salvator merianae), which also come in red (Salvator rufescens) and gold (Tupinambis teguixine) varieties, are newcomers to the growing list of invasive species that threaten to invade park ecosystems.

Tegus, a black and white lizard that is not venomous, is native to Brazil, Paraguay, eastern Uruguay and northern Argentina, but they soon found Florida’s climate to be their taste. They tolerate both fresh and salt water, maneuver easily through both tangles of vegetation and sawgrass prairie, and are adept at taking over the burrows of other animals. Plus, there’s plenty to eat.

A recent study by the US Geological Survey noted that the tegus can adapt to cooler temperatures than species tolerated in its native Argentina.

“Several lines of evidence from recent USGS research studies published from 2018 to 2021 now provide a clear indication to managers that the entire southeastern portion of the United States is at risk of becoming established if lizard releases continue. continue unabated,” said Amy Yackel Adams, a USGS. research ecologist earlier this year.

Lizards were first considered a threat to egg-laying species in Florida in 2013, 11 years after they appeared in pet stores across the state. Four years later they were documented in the park, and in 2020 some hatchlings were captured by staff.

“So we know, at least in 2020, that they were breeding [in the park]”Donmoyer said while checking a trap baited with chicken eggs not far from the Daniel Beard center in the park.

While female tegus can lay nearly three dozen eggs a year, it is unknown how many are free-ranging in the park.

“We don’t know what the population is,” he said. “With our current methods, even though we have improved in eliminating them, we are not yet at the point where we can fully achieve something that we would call eradication. The population continues to grow. learn as much as we can as we go, and keep pushing the [capture] numbers, learning more and more about biology.”

The Everglades aren’t the only place in Florida where lizards are causing trouble. Statewide, more than 12,000 tegus have been captured, according to the Florida Fish and Wildlife Conservation Commission, which added the lizard to its list of prohibited species in the state.

“Between October and February, they are basically inactive,” Donmoyer explained. “When we get the traps out in February and we [catch] one or two a week.

About 300 traps have been placed in the park and the areas just to the east, and technicians check them regularly during the warm months. In April, the traps caught about 10 tegus per day. As the months warm, the lizards become more active and find themselves in traps more often, the biologist said.

Biologist Kevin Donmoyer checks a tegu trap baited with a chicken egg/Kim O'Connell

Biologist Kevin Donmoyer checks a tegu trap baited with a chicken egg/Kim O’Connell

“The latest models have tegus potentially extending as far north as North Carolina and as far west as Texas, so it’s not necessarily a problem just in Florida,” Donmoyer said. “And there’s a population in Georgia. Tegus are extremely generalists with what they eat, so they’re going to eat fruit, they’re going to eat insects, mammals, other reptiles. Our big concern here is eggs. They’ve been documented eating alligator eggs. . We know they’ll eat turtle eggs, bird eggs.”

Captured lizards are taken to the park’s laboratory, where they are stored in hard plastic bins with lockable lids. From there, they are humanely destroyed and autopsied, the biologist said.

As the battle against tegus continues, there is always the possibility of another reptilian invader appearing.

“We don’t have monitors [lizards] in the park, which we are aware of,” Donmoyer said. “But we have smaller species of lizards. They are mostly, to our knowledge, limited to car parks. So they’re hitchhikers on the cars, they’re in the undercarriage. They jump into another parking lot and jump into one of our parking lots. Stone Agamas of Peter [native to East Africa]northern curly-tailed lizards [native to Bahamas, Cayman Islands, and Cuba]. These are two non-native species that you will find quite often in Florida, especially in South Florida. »

But as climate change makes the southern part of the United States more suitable for Central and South American species, what will be the next invader to threaten the Everglades ecosystem?

Previous episodes of this series:

Traveler’s Special Report: The Invasion of the National Park System

Traveler’s Special Report: Invasive Fish in National Parks

Parks Audio Postcard | Fight the Russian Olive at Glen Canyon NRA

Travelers’ Special Report: Vegetative Invaders in National Parks

Charity dollars help fight invasive species in the national park system

Traveler’s Special Report: The Cost of Invasive Species in the National Parks System

Travelers Special Report: Fighting Invaders with Fire on National Battlegrounds

Travelers Special Report: Measuring Success Against Invasive Species

Parks Traveler Audio Postcards: Hog Wild

Travelers’ Special Report: Invasive Mammals and National Parks

Everglades National Park: Ground Zero in the Battle Against Invasive Species

Fill the Hole in the Everglades National Park Donut

This story was made possible by Cardno, now Stantec, a global environmental and engineering consultancy.

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