Why was a giant lizard roaming a Tampa Bay neighborhood?

Tom Eldon saw a cat stalking something in the grass. So he decided to stalk the cat.

Out on a midafternoon Sunday walk in Old Seminole Heights earlier this month, Eldon saw a 3-foot-long lizard not far from the river.

“I was in flip-flops,” Eldon said. “I didn’t want to get too close.”

Eldon was mostly concerned about the cat, he said. But the cat got about 2 feet from the lizard, jumped up on a little ledge and walked away. Eldon crossed to the other side of the street; he didn’t know how the lizard would react, and he didn’t want to find out.

The lizard was most likely an Asian water monitor, according to Ali Mulla, a conservation biology graduate student at the University of South Florida who’s studying a similar species, the Nile monitor.

While there are multiple known populations of Nile monitors throughout Florida, there isn’t a known established population of Asian water monitors in the Tampa Bay area, according to Lisa Thompson, a spokesperson for the Florida Fish and Wildlife Conservation Commission.

“Any sightings are likely of escaped or released captive animals,” Thompson said.

Mulla agreed.

“Pure black water monitors are popular among hobbyists,” he said in a text message to the Tampa Bay Times, referring to the color of the lizard Eldon saw.

Both Asian water monitors and Nile monitors are not native to Florida, and the wildlife commission considers them a high priority for removal due to their potential impacts on native wildlife.

Nile monitors, which vary in color from olive green to black with yellow stripes, arrived in Florida in the 1980s through the pet trade, Mulla said. Genetic studies show they’re imported from West Africa as wild hatchlings and are sold as pets. But their temperaments are hard to handle, and many owners end up releasing their lizards into the wild.

“This species in particular is not well tempered,” Mulla said. “They’re really defensive, really flighty. They get stressed easily.”

In other words, Nile monitors are “escape artists,” Mulla said. And they can grow to 6½ feet long, with the majority of that length coming from the tail.

There are two distinct populations in Cape Coral and southeast Florida, but they have been seen in the Tampa Bay area. Mulla said five or six Nile monitors now live in Ruskin.

He’s not sure where they came from; they could’ve been released, or they may have dispersed northward from Cape Coral, he said.

To keep monitors off your property, the wildlife commission recommends removing excess debris and maintaining landscaping in your yard.

If you see a Nile monitor in the wild, don’t fret. They act skittish and timid, and they’re eager to get away from people, Mulla said. But like most animals, if cornered, they will defend themselves — by whipping their tails.

“And it doesn’t feel good,” Mulla said. He would know. Earlier this month, while releasing a captured Nile monitor back into the wild for tracking, Mulla was whipped. (”It didn’t get me that good,” he said.)

Nile monitors will also bite in defense. But if they’re given adequate space, “there’s really not a risk of any harm,” Mulla said.

The greatest impact these lizards have is on native Florida wildlife; they’ll hunt for prey above or below ground, up in trees, and in water, both fresh and salt, according to the wildlife commission. With a generalist diet, Nile monitors will eat anything from turtle eggs to spiders to toads.

There have also been reports of the lizards eating chickens, but Mulla said it’s highly unlikely that they’ve eaten dogs or cats.

Mulla, however, is cautious to say Nile monitors are causing negative effects on the environment.

“It’s not about whether a monitor will eat a bird … it’s whether that happens frequently enough to have an effect on the population of that species of birds,” Mulla said.

Like all nonnative reptile species — including the green iguana — Nile monitors and Asian water monitors can be humanely killed on private property with landowner permission, according to the wildlife commission. A permit or a hunting license is not needed.

But they’re tough critters. People have shot Nile monitors with pellet guns, only to have the same lizards trapped by the city with pellets throughout their bodies, Mulla said.

The best course of action is to contact the state’s invasive species hotline at 888-483-4681 or report the sighting online at IveGot1.org. Taking clear photos and/or video and providing an exact location is helpful. The state also has an Exotic Pet Amnesty Program that allows pet owners to surrender legally or illegally kept nonnative animals “with no questions asked and without penalties.”

Fun facts

• Nile monitors can stay under water for up to 15 minutes.
• They can sleep almost anywhere: on branches, submerged in water or in burrows.
• Large female monitors can lay up to 60 eggs at a time.