(FLORIDA) — Another giant reptile is clawing its way toward disrupting the South Florida ecosystem as an invasive species.
The Nile monitor — a semi-aquatic lizard equipped with razor claws that can grow up to 6 feet — has been establishing populations in the area since the 1980s, according to ecology experts.
Endemic to the Nile river delta in Sub-Saharan Africa, the continent’s largest lizards arrived in Florida via the pet trade, through both intentional and unintentional release, Frank Mazzotti, a professor of wildlife ecology at the University of Florida, told ABC News.
“They’re very wild, they’re very active,” Mazzotti said. “They don’t make good pets at all. They don’t calm down.”
The temperament of the giant lizards also makes them difficult to catch. Mazzotti described Nile monitors as “very strong” and “very aggressive.”
The reptiles will put up a fight and even bite humans who attempt to make contact with them, Mazzotti said.
“They’re crazy,” he said. “They’re very hard to handle, and you have to take great care that they don’t escape and that you don’t get bit.”
Monitor lizards are one of the high priority nonnative species for removal due to their potential impacts on native wildlife, Lisa Thompson, a communications specialist for the Florida Fish and Wildlife Conservation Commission (FWC) Division of Habitat and Species Conservation, told ABC News via email.
Current management approaches focus on containing established populations and preventing the establishment of new populations, as well as recurring surveys and removals, Thompson noted.
Nile monitors are now established in Lee and Palm Beach Counties, with multiple sightings in Broward County as well. The FWC is also monitoring observations of the species in Miami-Dade County, according to Thompson.
The state’s humidity allows the Nile monitors to thrive, Mazzotti said.
“Their habitat requirements are met,” he said. “The climate’s a match.”
In addition, their diverse diet and ability to travel over land and in fresh and saltwater allows for potential establishment throughout Florida, especially in coastal areas with mangroves and salt marshes.
South Florida’s extensive canal system can provide ample corridor, and they have a high reproduction rate, according to the FWC.
The giant lizards are “generalist” feeders, meaning they aren’t picky about what they eat, Mazzotti said.
They have been observed to eat crabs, crayfish, mussels, snails, slugs, termites, caterpillars, beetles, spiders, grasshoppers and crickets, fish, frogs, toads, lizards, turtles, snakes, young crocodiles and other reptiles, birds and their eggs and small mammals, according to the FWC. They can hunt for prey on the surface, below ground and in trees.
Some researchers have even observed them eating iguana eggs, Mazzotti noted.
“They don’t care what they eat,” he said.
Due to their generalist diet, the invasive reptile could impact state and federally listed threatened species, including sea turtles, wading birds, gopher tortoises and the American crocodile, according to the FWC.
Biologists and ecologists are also concerned about burrowing owls, as their largest population also occurs where the largest known Nile monitor population also occurs.
Nile monitors are not protected in Florida, except by anti-cruelty laws, and can be humanely killed on private property with the landowner’s permission, according to the FWC.
It was added to Florida’s Prohibited Nonnative Species List in April 2021, which limits possession of Nile monitors for the purposes of research, educational exhibition, control or eradication.
Nile monitors are often olive green to black in color and have stripes on their jaw and head. They also have yellow-ish V-shaped stripes that begin at the base of its skull and neck and transform into “bands” along their back, according to the FWC.
They are often seen in or close to water and basking on rocks and branches, wildlife experts say.
The reptiles are usually active during the day and sleep on branches or submerged in water at night.
When temperatures drop, Nile monitors will retreat to burrows to keep warm, the FWC noted.
While they have not yet had demonstrated impacts on the ecosystem, it’s important to keep populations of Nile monitors under control before they disrupt an already delicate environment, Mazzotti said.
“You cannot wait until an invasive species has demonstrated its impact upon the ecosystem,” he said. “Because if you do, then it’s too late.”
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