Reptiles

Tegu

Salvator and Tupinambis · also called tegus, Argentine black and white tegu

Least Concern → omnivorecarnivore Savanna & grassland Temperate grassland Rainforest

A tegu is South America’s answer to the monitor lizard: a metre-plus, heavy-bodied, forked-tongued omnivore that digs, swims, raids nests, and is smart and calm enough to be walked on a harness. It also does something almost no other lizard does — heats its own body up to 10 °C above the night air during the breeding season. Released pets have made it a serious invasive problem in the southeastern United States.

Overview

Tegus are large lizards of the family Teiidae (kin to the whiptails), across central and eastern South America — savanna, grassland, thorn scrub, gallery forest, and farmland. The best known is the Argentine black and white tegu, up to 1.5 m and 4–7 kg. All are omnivores, eating insects, small vertebrates, carrion, fruit, and — notoriously — the eggs of ground-nesting birds and reptiles, dug out of turtle, tortoise, and alligator nests.

A lizard that warms itself

In the spring breeding season the Argentine tegu holds its body 5–10 °C above ambient overnight, generating the heat internally. Outside that season it is an ordinary ectotherm. This partial, seasonal warm-bloodedness, confirmed in 2016, is one of very few known cases in a living lizard.

Smart, and a good digger

Tegus recognise their keepers, can be house-trained and harness-walked, and solve problems well — which is why they are popular pets. They dig deep burrows, brumate underground through the winter in the cooler parts of the range, and the female builds a large mounded nest and guards it through incubation, which is rare among lizards.

Status

The main species are Least Concern and common, adaptable to farmland, though heavily traded for skin (one of the top reptile leathers) and meat. Escaped Argentine tegus now breed across parts of Florida, Georgia, and South Carolina, raiding alligator and gopher tortoise nests, and are trapped year-round.

Tegu: common questions

Are tegus good pets?

For an experienced keeper with space, they are among the best pet lizards, and the Argentine black and white tegu in particular is prized for being large, striking, curious, and unusually calm and interactive, often described as dog-like. It can learn its name, tolerate handling, and be trained. The caveats are significant, however. A tegu needs a very large custom enclosure, typically at least 2 by 1 metres of floor space for an adult, strong heating and UVB lighting, a deep substrate for digging, a varied omnivorous diet, and a keeper prepared for a strong animal with a serious bite and claws. It also lives 15 to 20 years. Buying captive-bred is important, and in several US states tegus are now regulated or banned because of the invasive populations.

How is a tegu different from a monitor lizard?

They are not closely related but fill similar roles on different continents, a case of convergent evolution. Tegus are New World lizards in the family Teiidae, the same family as the whiptails and racerunners, found only in South America. Monitor lizards are Old World, in the family Varanidae, and include the Komodo dragon. Both are large, active, intelligent, carnivorous-to-omnivorous lizards with long necks, forked tongues, and powerful limbs, and both dig and swim well. Tegus tend to be stockier with a shorter neck and are more omnivorous, eating a lot of fruit, while most monitors are more strictly carnivorous. A tegu also has beaded, non-overlapping scales and a distinct forked tongue similar to a snake's.

Why are tegus a problem in Florida?

Argentine black and white tegus were imported in large numbers for the pet trade, and animals that escaped or were released have founded self-sustaining wild populations in southern and central Florida and have since spread into Georgia and South Carolina. They are a concern because they are large, hardy, cold-tolerant enough to survive Florida and Georgia winters by burrowing, and they eat almost anything, including the eggs of the American alligator, the threatened gopher tortoise, sea turtles, and ground-nesting birds such as quail. They also compete with native predators and can carry parasites and salmonella. Florida now allows year-round removal of wild tegus and has restricted the pet trade in the state.

Is it true that a tegu is partly warm-blooded?

Yes, in a limited, seasonal way that was only confirmed in 2016. Researchers found that during the reproductive season in spring, Argentine black and white tegus kept their body temperature well above that of their burrow and the night air, by as much as 10 degrees Celsius, and that this warmth was generated internally rather than stored from daytime basking. Outside the breeding season the same animals were ordinary ectotherms, tracking the ambient temperature. This partial, facultative endothermy is thought to help the tegu stay active and support reproduction early in the season, and it is one of the few known examples in a living lizard, offering a possible window into how full warm-bloodedness evolved.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Salvator and Tupinambis
Diet: A true omnivore taking insects, spiders, snails, crabs, small mammals, birds, frogs, other lizards, snakes, and carrion, a great deal of fruit, seeds, and flowers, and, notoriously, the eggs of ground-nesting birds and reptiles, dug out of the nests of turtles, tortoises, alligators, and quail
A lizard that heats itself: During the spring breeding season the Argentine black and white tegu can hold its body 5 to 10 degrees Celsius above the surrounding air overnight, generating the heat internally rather than from basking, one of the very few lizards known to show this partial, seasonal form of warm-bloodedness
Big, and built like a small monitor: The largest tegus reach 1.2 to 1.5 m in length and 4 to 7 kg, with a heavy body, a long muscular tail, strong digging claws, a forked tongue flicked like a snake's, and beaded skin, and they are the New World ecological counterpart of the Old World monitor lizards
Unusually smart and tractable: Tegus are among the most trainable of lizards, recognise their keepers, can be house-trained and walked on a harness, and in tests show problem-solving and quick learning, which along with their calm temperament has made them popular in the exotic pet trade
They dig deep burrows and brumate: Tegus dig extensive burrows for shelter and egg-laying, and in the cooler parts of their range they spend the winter dormant underground for several months, a state called brumation, emerging in spring to feed and breed
Females build and guard a nest: A female tegu constructs a large mounded nest of soil and plant matter, lays around 20 to 35 eggs in it, and unusually for a lizard stays to defend the nest against predators through much of the roughly two-month incubation
An invasive problem in Florida and Georgia: Escaped and released pet Argentine tegus have established breeding populations across parts of Florida and into Georgia and South Carolina, where they raid the nests of the American alligator, gopher tortoise, sea turtles, and ground-nesting birds, and wildlife agencies now trap them year-round and urge the public to report and, where permitted, remove them
Range: Central and eastern South America, with the Argentine black and white tegu from central Brazil through Paraguay, Uruguay, and Bolivia to central Argentina, the gold tegu and other species across the Amazon basin and the Guianas, and the red tegu in the dry Chaco, in habitats from rainforest and gallery forest to savanna, grassland, thorn scrub, and farmland, plus introduced populations in Florida, Georgia, and South Carolina.
Conservation status: Least Concern → ≈ The main tegu species are assessed as Least Concern and remain common across their large South American ranges, adapting well to farmland and disturbed habitat, though they are hunted for meat and for their skin, which is one of the most heavily traded reptile leathers, with millions of Argentine tegu skins exported over past decades under a quota and monitoring system, and localised populations can be reduced by intensive collection and habitat clearance in the wild