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In South Florida, where the Everglades meet the bays, environmental challenges abound. Sea level rise threatens homes and real estate. Invasive species imperil native plants and animals. Pesticides reduce the risk of mosquito-borne diseases, but at what cost? WLRN's award-winning environment reporting strives to capture the color and complexity of human interaction with one of the most biodiverse areas of the planet.

2019: The Year Of The Big Lizard

Florida Fish and Wildlife Conservation Commission
Trappers caught this water monitor in Key Largo in May.

Across South Florida, 2019 is shaping up to be the year of the big lizard.

At their yearly gathering to talk about invasive species this week, more than 200 scientists from universities, state and federal agencies and national parks said the spike in big lizard sightings has caught them by surprise. In addition to green iguanas and tegus, nile monitor lizards, water monitors, spiny-tailed iguanas and rhinoceros iguana appear to be spreading.

"We're really seeing this kind of surge in a number of these large lizard species in South Florida," said Jennifer Nestler, a project manager at the University of Florida's Croc Docs lab. Reports of Nile monitors led the team to a water monitor and a spiny-tailed iguana, she said.

"It's a little bit surprising, but we're glad that we're learning about them so that we can do something," she said.

Credit Carl Juste Miami Herald
University of Florida researchers say they are succeeding at driving down the number of tegus where they set traps, but the lizards continue to spread.

Pythons remain a major problem for South Florida. The South Florida Water Management District and Florida Fish and Wildlife Conservation Commission has now bagged more than 2,700 snakes. But the undertaking remains expensive: an FWC analysis of the two years of trapping put the cost at $228.82 per snake.

Scientists know they need to find more efficient and cheaper methods, so they're using modeling and chemistry. A team from the U.S. Geological Survey is exploring using sex pheromones loaded into tracking devices. They're also modeling snake behavior to predict when and where to find the snakes.

Where they live also seems to determine what they eat, said UF wildlife ecologist Christina Romagosa. They've been blamed for driving down the population of small mammals in the Everglades. Snakes caught in the region now appear to be eating more rodents, but that could be because more young snakes are captured there, she said. In Southwest Florida, small mammals dominate their diet.

An April study found the snakes are congregating around tree islands in the Everglades, suggesting they're starting to prey on wading bird. Necropsies have found roseate spoonbills and white ibises in their guts. Romagosa said researchers are still trying to get a handle on how their impacting populations.

The research isn't stopping at snakes. Researchers are modeling tegu behavior to find better ways to trap them. The spread of iguanas is also becoming more pressing with the city of Key West and Monroe County upping efforts.

Plants don't grab as many headlines, but can cause just as many problems. Invasive mangroves that escaped from Fairchild Tropical Garden more than a decade ago continue to spread along Biscayne Bay, FWC's Dennis Giardino said. And Brazilian pepper has spread among protected mangroves in the Ten Thousand Islands along the southwest coast, said FWC's Jackie Smith. Because the area is so remote and mangroves are protected, weeding out the pepper is difficult, she said.

There's also cost. Last year, the state spent just $3 million on invasive plant removal.