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Living Sanibel: Nile monitor lizard

By Staff | Apr 15, 2015

Currently known to exist in seven south Florida counties, the Nile monitor lizard represents a serious potential environmental threat. This powerful lizard is a carnivore. It is a distant relative of the Komodo dragon of Indonesia, the largest lizard in the world, known to obtain lengths of 10 feet and weigh more than 300 pounds. The Komodo has been known to kill children, goats, and dogs.

With a keen sense of smell, excellent speed, and sharp eyesight, the monitor lizard, once established in a region, could quickly decimate a wide range of native animals. In Africa, where it originates, it is one of the leading predators of crocodile nests. On barrier islands, if it becomes established there, it could turn its attention to alligator and sea turtle eggs. Equipped with sharp claws, it would have no trouble digging up loggerhead nesting sites and devouring all the eggs in a single night. A strong climber, this predator could do significant damage to bird rookeries and small mammal populations.

The Nile monitor has established a beachhead in northern Cape Coral where it can sometimes be spotted foraging for food during the day. These massive lizards were probably released as pets, though importing and keeping the Nile monitor in Florida is now allowed by special permit only. Every imported animal must also be identified with a microchip, ensuring that the owner will remain responsible for each lizard’s continued captivity.

A young Nile monitor lizard can be easily handled as a pet, but by the time it reaches two or three years of age, it is a ferocious lizard capable of killing a housecat with a single bite and swallowing it whole. Not surprisingly, the pet owner may want to remove this danger from the household.

The first reported sighting of a Nile monitor in southwest Florida was in 1990, and the population is now estimated at more than 1,000. It may lay up to 60 eggs in a clutch and is capable of parthenogenesis, which means that a single individual can reproduce without mating. In Africa this lizard is kept in check by other lizards and birds of prey that feed on the eggs and young. Larger lizards are sometimes killed and eaten by leopards and other wild cats. In Florida, alligators, panthers, and bobcats are its only natural predators.

If you see or suspect you see one of these lizards, which resemble giant brown anoles only much darker and without the dewlap, please call Florida Fish and Wildlife at (850) 488-4676 to report the sighting.

This is an excerpt from Living Sanibel – A Nature Guide to Sanibel & Captiva Islands by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry’s and your favorite online sites.