Environment

Voracious tegus on the move in South Florida

Argentinian Tegu lizards trapped in South Dade

A pair of researchers with the University of Florida trap Argentinian Tegu lizards near Homestead on Sept. 9, 2016. The Tegu is the latest non-native specie to actively breed in South Florida.
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A pair of researchers with the University of Florida trap Argentinian Tegu lizards near Homestead on Sept. 9, 2016. The Tegu is the latest non-native specie to actively breed in South Florida.

A voracious South American reptile invading marshes in Miami-Dade County might have staked a claim in new territory: Florida Power & Light’s cooling canals at Turkey Point.

Since the spring, researchers for the first time have trapped four tegus near the 5,900-acre grid of canals, a dangerous sign that the egg-eating predators have been drawn to one of the nation’s few breeding grounds for rare American crocodiles. If tegus are indeed on the move, they would have traveled eastward more than 10 miles from marshes that border Everglades National Park, where biologists first warned that an invasion may be occurring.

They’re not staying put. And the capture rates don’t look like they’re diminishing yet.

University of Florida biologist Frank Mazzotti

“They’re not staying put. And the capture rates don’t look like they’re diminishing yet,” said University of Florida biologist Frank Mazzotti, who heads the school's tracking and trapping efforts.

Tegus first arrived in South Florida via the exotic pet trade about 2002. Within a decade, Mazzotti and others sounded the alarm that the cold-hardy, omnivorous, fecund lizard — females lay up to 35 eggs at a time — could become another invasive threat, with two potential breeding populations established near Florida City and the Tampa area.

Biologists worry that if tegus continue to spread, crocodile nesting grounds managed by the utility for 25 years and credited with helping revive the once-endangered species could be in peril. They were upgraded to threatened in 2007.

“This is one of the times I can correctly say they literally eat everything: plants, seeds, insects, small animals, birds, snakes, frogs. They eat everything,” Mazzotti said. What’s more worrisome is their hankering for eggs.

A camera aimed at a turtle nest once recorded tegus consuming the entire nest in a single feast, Mazzotti said. “They went in and just ate it like popcorn.”

1-888-Ive-Got1 andwww.IveGot1.orgThe phone number and web site for reporting tegus to state wildlife officials.

This spring when tegus emerged from their winter hibernation, FPL ran a line of traps and set up cameras on the western border of the canals to “create a curtain to block that migration into croc territory,” said Amy Albury, the utility’s director of environmental relations and sustainability. Over the spring, they snared four. So far, no evidence suggests tegus are harming the croc population, she said. But if they spread near the canals as rapidly as they spread to the west, that could change.

Last year, nearly 760 tegus were trapped in the area, setting a new record, said Kristen Sommers, a section leader for the Florida Fish and Wildlife Conservation Commission’s division of habitat and species conservation. With the trapping season set to end next month, this year will likely see similar numbers, she said.

That means tegus are climbing something called the invasion curve, a measure biologists use to assess exotic pests. Low on the curve, it’s possible to contain them. Past a certain point they could become the next Burmese python. With numbers continuing to soar, and tegus still widely available in pet stores, wildlife agencies last year teamed up to better coordinate efforts. They set a goal of containing the tegus — everyone recognized they were too late to eradicate them — and also enlisted FPL. UF trappers also focused on catching juveniles, upping their count from two last year to 50 this year.

To the west of Florida City, biologists are also keeping a close watch on the border with Everglades National Park, where sweeping sawgrass marshes offer an escape inaccessible to trappers. Park officials maintain a line of traps checked daily, said Tylan Dean, chief of the park’s biological resources branch. But he worries about land the park can’t monitor.

I would say we have good coverage along the park perimeter near Florida City. But my concern is that we don’t have much effort north of that.

Tylan Dean, chief of the Everglades National Park biological resources branch

“I would say we have good coverage along the park perimeter near Florida City. But my concern is that we don’t have much effort north of that between Florida City and Homestead,” he said. “We know there’s tegus in that area, but it’s really difficult to work there because it’s private land.”

Biologists are also scrambling to find a missing piece of the puzzle needed to better manage trapping efforts: a population count. Last year, they attached GPS trackers to some tegus and released them. They also set up cameras near traps along with roads and levees that tegu travel. Without a reliable count there is no way to tell if trapping is controlling the population. It’s critical information that Mazzotti worries may come too late.

“We essentially spent four years watching them do this. This is what happens when you don’t bring in control efforts early,” Mazzotti said. “Government comes up with all the reasons why it can’t act faster, but the tegus don’t care. They can’t say we understand there are budget problems so we won’t reproduce this year. No, that’s not how it works.”

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