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Monday, Jun 18, 2018
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Scientist takes on 4-foot lizards in Riverview

Tessie Offner steps out of her state-owned pickup that’s packed with traps and crates in the middle of a preserve in the middle of nowhere way east of Riverview.

Her directive is clear: Find a way to stop the spread of an invasive lizard that can grow to 4 feet long -- a beast that scuttles through the underbrush plundering nests, eating defenseless native species and the eggs of the protected gopher tortoise. It would be nice to eradicate tegus from these woods, but controlling the population is the more likely scenario. It appears the cold-blooded, fork-tongued interloper has muscled its way into the Florida landscape and is here to stay. Tegu sightings have more than doubled since April.

Offner, a biologist with the Florida Fish and Wildlife Conservation Commission who specializes in non-native species, is assigned the full-time task of trudging through these woods every day looking for the creatures, tracking their movements and trapping them.

She straps on a backpack that includes a water bottle,a GPS, a clipboard and a half dozen raw eggs for bait and heads for the woods.

It’s a nearly undisturbed tract, thick with live oaks, slash pines and palmettos. A field of waist-high wild blackberry bushes interrupts the shade offered by the trees, under which mosquitos buzz and colorful banana spiders the size of sycamore leaves hang their 8-foot-wide webs.

“The goal here is to protect the native wildlife,” Offner says. “If we are not doing that, we are not doing our jobs.”

The Argentinian tegu, known to scientists as Tupinambis merianae, is not native to Florida but has established a colony near Riverview, one of three growing populations, she says. She’s studying the species to see where the lizards go, how they live, if the population can be controlled, perhaps eradicated, though the odds of that are slim once a colony gets established.

Tegus are cagey and know how to hide themselves.

“They’re very wary, aware of their environment,” Offner says. “If they hear you coming, they go hide. I’ve been out here two years and I can count on one hand the times I’ve seen a tegu running freely.”

She’s trapped a fair share, though. In those two years, she’s trapped 35 tegus in or near this preserve. They are studied and euthanized, their scaly bodies given up to scientists who determine their diet and whatever else can be gleaned from cutting one open and looking inside.

They are shown respect due any living creature, she says, before they are dispatched.

“We do try to treat the animals as humanely as possible when we trap them,” she says. Fish and Wildlife won’t say how the animals are killed but says the agency follows the recommendations set by the American Veterinary Medical Association, which allows several methods of euthanasia for reptiles.

Tegu traps are set only between February and October, when the lizards are most active. They get a pass in the winter.

The two other viable tegu populations in Florida include a small one in Polk County and one in Miami-Dade County, where there have been more than 700 sightings. Tegus in the wild mostly likely were pets that either escaped or were set free. They are popular as pets and are legal to own.

Tegus can weigh up to 30 pounds. They aren’t aggressive but can give a good bite if they feel threatened.

Offner pulls out Ragu, a pet tegu she uses to educate people about the lizard. The creature is docile, until she holds it in the sun for a few minutes, when the heat brings it to life. It gets antsy, whipping its tail around her waist, squirming in her grip and flicking its bubble-gum-colored tongue in and out.

They are causing a concern because they are a reptile that can survive the cold winter temperatures around Central Florida. They inter themselves in burrows and can live through nights that are near freezing.

The Riverview population lives in an area bordered by Rhodine Road to the north, Boyette Balm Road to the east and Balm Riverview Road to the west. Within that triangle, nearly 150 sightings of tegus have been reported. It’s unclear how many are actually traipsing around Hillsborough County.

Sightings can be reported to a hot line at 1-888-483-4681 or online at IveGot1.org, and any photos taken of the lizards and their exact locations are helpful, Offner says.

Natives of Brazil, Paraguay, Uruguay and Argentina, tegus can be prolific if conditions are right. Females can lay up to 35 eggs a year. They are black and white with banded tails and spend most of their time on land, though they can swim and submerge themselves for long periods of time. They are active during the day and will burrow at night to hide.

Little is known of their habits here in Florida, Offner says. That’s what she is trying to research.

She walks through the woods, setting two traps using chicken eggs as bait. She checks three traps already set. One is empty. The other two contain shame-faced raccoons.

Both are released and scamper into the underbrush, happy to be free but showing no gratitude for the free chicken egg.

In all, there are 15 to 20 traps on this county-owned preserve, she says, and on some privately owned adjacent land. Offner and a team of volunteers come out here every day, she says, to look for tegus, check and set traps and to release any animals caught by accident.

She knows these woods pretty well, pointing out where traps are set and where some motion-sensor cameras are mounted to catch wildlife movement, mostly around gopher tortoise burrows. “This,” she says, “is a 40-hour-a-week job for me.”

She watches for all the creatures who call these woods home, gently pushing aside a spider web as she passes by. “Sorry about that, buddy,” she says.

“I think all animals are fascinating,” she says. “It’s always a surprise when I come out here. I always find something new.”

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