Florida’s warm, subtropical climate allows several species of large, non-native lizards to establish permanent populations, particularly in the southern half of the state. These reptiles are often mistaken for native wildlife due to their size and widespread presence. Three primary species account for most prominent sightings, each having a distinct appearance and behavior.
The Arboreal Invader: Green Iguanas
The Green Iguana (Iguana iguana) is perhaps the most recognized of Florida’s large, non-native lizards, known for its preference for elevated perches. Mature males often grow between five and six feet long, including their tail. Although their name suggests a uniform color, their appearance varies significantly, ranging from bright green in juveniles to dull green, gray, or even striking orange in breeding males.
A prominent identification feature is the large, rounded scale on the cheek and a dewlap hanging beneath the jaw. They also possess a row of spike-like scales running down the center of their back, which are typically longer in males. Green Iguanas are strictly arboreal, spending most of their time in trees or on structures near water sources like canals and lakes.
They are diurnal, active during the day, and often bask in the sun to regulate body temperature. When threatened, they typically drop into the water and swim away, demonstrating a strong semi-aquatic nature.
Ground-Dwelling Giants: Tegus and Monitors
The Argentine Black and White Tegu (Salvator merianae) is a stocky reptile that can grow to nearly five feet in length. Its body is covered in a distinctive mottled pattern of black and white, often arranged in bands across its back and tail. Hatchlings exhibit a vibrant green coloration on their heads that fades to the adult pattern after about a month.
Tegus are omnivorous, consuming fruits, insects, and the eggs of ground-nesting animals. They are most often seen in disturbed habitats like roadsides and forest clearings. During cooler winter months, the tegu enters a hibernation-like state, known as brumation, retreating into burrows or under cover.
The Nile Monitor (Varanus niloticus) is another large, ground-dwelling lizard, but with a more slender build than the tegu. These African natives can exceed five feet in total length, sometimes reaching up to six and a half feet. Their coloration is a gray-brown or olive-brown base marked by bands of lighter, often yellowish, spots.
The Nile Monitor’s tail is long and laterally compressed, resembling a rudder for strong semi-aquatic movement. They are highly predatory, feeding on eggs, fish, small mammals, and other reptiles. They are frequently found near water, often basking on canal banks or seawalls.
The Origin Story: How Non-Native Lizards Arrived
The presence of these lizards in Florida is directly linked to the exotic pet trade. Many non-native reptiles now breeding in the state were originally imported as pets. Owners often release them into the wild when the animals grow too large, become aggressive, or the cost of care becomes prohibitive. Accidental escapes from breeding facilities and private collections have also contributed to establishing wild populations.
Florida’s warm, subtropical climate mirrors the native habitats of these species, allowing them to survive year-round and reproduce successfully. This hospitable environment, combined with a steady influx of released animals, has made Florida a hotspot for the establishment of non-native reptile species.