FORT MYERS, Florida – Nile monitor lizards that can grow to over 5 feet long and weigh close to 15 pounds are spreading through Florida.
The invasive species are known in their native Africa to prey or scavenge for a variety of small animals, including domestic cats.
In areas where Nile monitors are abundant in Florida, they have also attacked small pets and livestock such as chickens.
Nile monitors are skillful climbers and adept swimmers that can remain underwater for 12-15 minutes.
The Nile monitor’s high reproduction rate, diverse diet, and ability to travel over land and in fresh and saltwater allows for the potential establishment throughout Florida, particularly in coastal areas dominated by mangroves or salt marshes.
In the Sunshine State, Nile monitors could impact populations of nesting birds (especially burrowing owls), gopher tortoises, nesting sea turtles, nesting American crocodiles, and other species listed as threatened or endangered.
Nile monitors are established in Lee and Palm Beach Counties, although observations have occurred throughout the state including multiple observations in Broward County. South Florida’s extensive canal system may provide dispersal corridors for the species, which tend to inhabit water edges.
Researchers believe populations of Nile monitors in Florida stem from intentional and unintentional releases from animals in captivity. Nile monitors may escape confinement by pushing off the tops of cages or by using their sharp claws to tear through screens.
They may be intentionally released if they become difficult to feed, manage or handle or if they are deemed unfit or too sick to sell in the reptile trading industry. Nile monitors may also escape from facilities destroyed by hurricanes.
“Nile monitors eat a wide variety of food items including small mammals, reptiles, fish, amphibians, and more,” said biologist Jenny Ketterlin Eckles. “Because their diet is so varied, we are assessing whether this species may have an impact on Florida’s native wildlife.”
The Florida Fish and Wildlife Commission cautions that members of the public should not attempt to capture the Nile monitor themselves. Monitors are not innately aggressive but like any wild animal, they may defend themselves if aggravated or threatened.
Instead, FWC asks that the public take a picture of a suspected Nile monitor and immediately report it online to IveGot1.org or by phone at 888-Ive-Got1 (888-483-4681).
The monitor’s body color can range from light yellow to dark olive or brown. They have a pattern of light yellow markings on the back, which appear as bands or stripes closer to the head and tail.
FWC says that other lizards can easily be mistaken for Nile monitors, including green iguanas, spiny-tailed iguanas, curly-tailed lizards, and other reptiles.
“Color and pattern variation is pretty common, so the most effective way to verify the species is to take a picture of the animal and submit it along with a report of your observation,” said Eckles.