Argentine Black and White Tegu (Salvator merianae)

Meet South America's largest lizard! Smart, strong, and surprisingly warm-blooded! The Argentine black and white tegu can sprint on two legs, crush prey with its powerful jaws, and even recognize its keepers.

The Argentine black and white tegu is a large, stocky lizard native to South America and is the largest of the “tegu” lizards. Adults have bold black and white markings with beaded scales often arranged in bands across the back and tail. Hatchlings are born with bright green coloration on their head and upper body, which fades after a few months, turning into the adult black-and-white pattern. Males are notably bigger and bulkier than females, often developing large jowls (“chubby cheeks”) that house powerful jaw muscles. This species is known for its intelligence and relatively docile nature when acclimated to humans. They can even be housebroken to some extent. However, they are still wild reptiles; when threatened, tegus can be defensive. They have strong jaws, sharp teeth and claws, and a long, muscular tail that can deliver a forceful whip. Uniquely, Argentine tegus are one of the only reptiles known to be partially endothermic, capable of raising their body temperature above the surroundings during the breeding season. Overall, their combination of impressive size, striking coloration, and curious, intelligent demeanor makes them a fascinating ambassador for South American reptiles.

Quick Facts Summary:

Habitat: Tropical rainforests, dry forests, savannas, and semi-deserts of South America; also found in shrublands and agricultural areas. They shelter in burrows or dense vegetation to avoid temperature extremes.
Geographic Range: Native to eastern and central South America – including south/southeastern Brazil, Paraguay, Bolivia, Uruguay, and northern to central Argentina. (Introduced invasive populations exist in parts of Florida and Georgia in the USA)
Diet (Wild and Captive): Omnivorous. In the wild, juveniles eat mostly insects and other invertebrates plus some fruits, while adults consume a broad diet of fruits, eggs, and small animals (birds, reptiles, rodents, etc.). In captivity, they are fed varied diets including insects, rodents, eggs, lean meats, and fruits/vegetables to ensure balanced nutrition.
Size (Length/Weight): A large adult male can reach about 4 to 4.5 feet (120–140 cm) in total length, and females around 3 feet (91 cm). Adult males are heavier, weighing around 7–8 kg (15–18 lbs) on average, with some exceptional individuals approaching 10+ kg (22 lbs).
Lifespan: Approximately 12–15 years in the wild, and commonly 15–20 years in captivity with proper care. Some individuals have lived over 20 years under human care.
Temperature/Humidity Preferences: As a tropical reptile, it thrives in warm temperatures. Tegus prefer a warm environment (daytime ~80–95°F with hotter basking spots) and moderate to high humidity (60–80%) to stay healthy. In cooler seasons they undergo brumation (a hibernation-like dormancy) to cope with lower temperatures.
Venomous/Dangerous?: Not venomous. Argentine tegus have no venom glands. They are generally not aggressive to humans if accustomed to handling, but they can deliver a powerful bite or scratch if provoked, and will defend themselves with hissing, tail lashing, and biting. Caution and respect are advised when interacting with them due to their strength.
Conservation Status: Least Concern (IUCN). The species has a wide distribution, a large stable population, and tolerance for varied habitats. It is not currently endangered. However, it is listed on CITES Appendix II, meaning international trade is monitored due to potential risks from over-collection.

Habitat & Natural Range

Argentine black and white tegus inhabit a variety of warm, subtropical to tropical environments in South America. They are found in eastern and central South America, primarily in Brazil (south of the Amazon Basin), Paraguay, eastern Bolivia, northern and central Argentina, and Uruguay. Within these regions, they occupy diverse habitats ranging from tropical rainforests and wet savannas to dry shrublands and semi-desert Chaco regions. Tegus often thrive in transitional or disturbed areas such as forest clearings, near roads and fence lines, and even agricultural lands. They tend to be ground-dwelling (terrestrial) and will dig burrows or use natural cavities for shelter. These burrows offer protection from extreme heat or cold and help the lizards maintain moisture, an important adaptation in both hot climates and seasonal cool periods. Tegus are adept swimmers as well, sometimes entering water to escape threats or heat; they can even stay submerged for extended periods if needed. In terms of climate, they are accustomed to hot, humid summers and mild winters. In the cooler months (approximately September to March in the wild southern range), Argentine tegus brumate underground to avoid cold weather. This ability to exploit burrows and become dormant during winter allows them to live as far south as central Argentina, where seasonal temperatures drop. Overall, their global distribution is limited to South America’s Neotropical realm, but they have shown remarkable adaptability to different terrains: from lowland rainforests near sea level to dry thorny scrub up to 1250 meters in elevation. Their adaptability has even enabled them to become invasive in parts of North America when introduced, demonstrating how well they can adjust to new environments (to the detriment of native wildlife in those areas).

In the wild, Argentine black and white tegus are true omnivores with a very opportunistic feeding strategy. Juveniles tend to eat a high proportion of animal protein, actively hunting insects, spiders, snails, and other invertebrates, providing the protein and fats needed for growth. Young tegus will also consume fruits and berries when available, and in doing so, aid in seed dispersal in their habitats. As tegus mature, their diet broadens and their plant intake increases.

Adult tegus have powerful jaws that enable them to prey on larger items. They will raid bird nests for eggs and chicks, eat reptile eggs or hatchlings, small rodents and other small mammals, frogs, lizards, and even carrion if they come across it. Plant matter remains important too: they eat a variety of fruits, vegetables, and seeds in season. Studies have shown seasonal variation in diet, for example, in spring, they may eat more protein (like eggs and small animals), while in summer, more fruits and insects are consumed as those become abundant. This flexible diet contributes to their success in the wild and also makes them hardy survivors in new environments.

In captivity, zookeepers and pet owners replicate this varied diet. A balanced tegu diet in human care often includes high-protein items such as gut-loaded insects, worms, and pre-killed mice or rats, plus healthy portions of fruits (like berries, melon, fig) and vegetables. Prepared foods like lean ground turkey or formulated reptile diets and the occasional egg can be offered for variety and nutrition. It’s recommended to include calcium and vitamin supplements as needed to ensure tegus get enough nutrients, since captive tegus can suffer deficiencies without the diverse wild foraging they’d normally do. One interesting note: Raw eggs are a favorite treat, but keepers often scramble or cook them slightly as raw egg whites contain avidin, a protein that can cause biotin (vitamin B7) deficiency, so cooking the eggs helps avoid health issues. Tegus have a keen sense of smell, much like snakes; they use their forked tongue and Jacobson’s organ to detect food. You might observe a tegu actively flicking its tongue to sniff out prey or fruit hidden in its enclosure. Whether in the wild or in a zoo, the Argentine tegu’s hearty appetite and omnivorous palate mean it plays an important role as both a predator and a seed disperser, helping control pests and spread plant seeds in its ecosystem

Diet

Reproduction & Lifecycle

A juvenile Argentine black and white tegu in the wild. Young tegus have similar patterns to adults, but hatchlings start off with a greenish head that fades as they grow.

Argentine black and white tegus have a well-defined breeding season and notable reproductive habits. In their native range, mating season occurs in the spring, usually shortly after tegus emerge from winter brumation. Males will seek out females using their keen sense of smell. Courtship can involve the male following and nudging the female. Once mating has taken place, the females exhibit remarkable nesting behavior. About 1–2 months after breeding, a female tegu will build a nest of grass, leaves, and soil in a concealed spot, often a burrow or under debris. She then lays a clutch of eggs, typically anywhere from 12 to 30 eggs in a single clutch. The female often coils her body around the eggs or stays nearby; this species is one of the few lizards known to guard its nest. Mother tegus are quite protective and will defend the nest against predators, even attacking animals that get too close.

Once laid, the eggs incubate for a lengthy period. Depending on temperature and environmental conditions, incubation can last roughly 2 to 4 months. In warmer artificially controlled settings, eggs have hatched in as little as 60 days, but in natural nests, the longer timeframe is normal. Hatching usually happens in late summer. Baby tegus, called hatchlings, emerge at 7–10 inches long. They are precocial, meaning they are relatively developed and capable of fending for themselves soon after hatching. Remarkably, however, baby tegus don’t always disperse immediately. There is evidence that the young stay with the mother for a short time after hatching, likely gaining protection from her presence until they are large enough to survive on their own. This level of parental care (nest guarding and remaining with young) is uncommon among reptiles and highlights the tegu’s advanced behavior.

After the first few weeks, juvenile tegus will venture out and live independently. Growth is rapid in the first two years. They eat voraciously to reach a substantial size quickly. Tegus generally reach sexual maturity by around 2 to 3 years of age, once they’ve grown to roughly 1.5 kg in weight. They continue to grow in size until about 4 years old, after which growth slows or stops. Throughout their life, Argentine tegus go through seasonal cycles of activity (spring/summer foraging and breeding) and dormancy (brumation in winter). In terms of lifespan, wild tegus often live around 12–15 years. In captivity, with optimal care, they commonly live 15–20 years, and some individuals have surpassed 20 years old.

Argentine black and white tegus are primarily diurnal lizards meaning they are active during the day and sleep at night. A typical day in the life of a wild tegu involves a lot of basking and foraging. They emerge from their burrows or shelters in the morning to soak up sunrays, warming their bodies since, like all reptiles, they rely on external heat to regulate their temperature. However, unique to the tegus is that during the breeding season, these tegus can elevate their body temperature a few degrees internally a rare trait for a reptile. Once warmed up, they roam their territory in search of food. Tegus are terrestrial and generally stay on the ground, though juveniles are more arboreal and may climb low branches or shrubs to avoid predators. Adults, being larger and less vulnerable, rarely climb and instead patrol the ground, using their forked tongue to pick up scents of fruit or prey.

In the wild, Argentine tegus are mostly solitary creatures. They do not form social groups, and adults typically tolerate each other only during the mating season or in brumation dens. Interestingly, while they live alone most of the year, in cooler regions multiple tegus may den together in a shared burrow for brumation. This is likely because suitable winter refuges are scarce. When active, a tegu can cover surprisingly large distances in search of food or mates. They are capable of bursts of speed and can even run on their hind legs, in a bipedal stance, for short distances when startled or defending territory. A startled tegu might sprint with front legs off the ground, mouth agape in an intimidating display meant to scare off rivals or predators.

In terms of disposition, Argentine black and white tegus have a reputation for being intelligent and can respond to training techniques, especially individuals that are captive-bred or handled frequently. Many zookeepers and pet owners describe them as curious and food-motivated; tegus can learn to recognize their keepers and may even come when offered food. However, when tegus feel threatened or stressed, they have a series of defensive behaviors. The first warning is often an audible one, in which they may start huffing or heavy breathing, a sign to back off. If the threat persists, a tegu may inflate its body and stand its ground, and you’ll see it lash its tail side to side. The strong tail can bruise or injure, so this is an effective deterrent. They might also stomp their front feet in a bold “dance” as part of the threat display. All of this is meant to avoid an actual fight, but if cornered, a tegu can charge forward and deliver a painful bite. Their bite, while not venomous, can cause lacerations due to sharp teeth, and the jaw strength of a large adult is enough to crack eggs or snail shells easily, so one can imagine a bite would hurt. In captivity, a well-socialized tegu is usually docile and can be handled safely, but handlers always respect these behaviors. Tegu owners learn to read the animal’s body language (for example, a tense posture or rapid breathing) to avoid pushing the lizard into defensive mode. In summary, Argentine tegus are generally calm, intelligent lizards with a mild temperament when comfortable, but they can become defensive if threatened. They use an array of impressive tactics to appear larger and more menacing to would-be attackers, ensuring their own safety in the wild.

Behavior & Temperament

Conservation & Threats

The Argentine black and white tegu is currently classified as Least Concern on the IUCN Red List. This favorable status is due to its wide distribution and abundant population in the wild. Surveys indicate that tegus are locally common throughout much of their range, and their population trend is considered stable at present. Furthermore, they tolerate a range of habitats, including some modified by humans, which has helped them remain plentiful.

At the same time, tegus do face certain threats in the wild, though none are causing major declines. Habitat loss is a concern in some areas, for instance, parts of Brazil and Argentina, where forests or savannas are converted to agriculture, have seen reductions in tegu habitat. Despite habitat changes, tegus have shown resilience by surviving in farmlands and even sugarcane or citrus plantations, as long as some shelter and food remain. Another threat is hunting and trapping. In countries like Argentina and Paraguay, tegus have been historically hunted for their skins and meat. Tegu leather is used in the leather trade, often labeled as “teiú” or just sold as reptile leather, and their meat has been used as bushmeat. Harvest for leather in particular was heavy in the late 20th century, but sustainable practices and farming of tegus have been introduced to mitigate overharvest. Additionally, capture for the pet trade is an ongoing pressure. Their intelligence and striking appearance make them popular as exotic pets worldwide. This demand has led to collection from the wild, though in recent years, more captive breeding by reptile breeders has reduced some pressure on wild populations.

From a legal and conservation standpoint, the species is protected to an extent: being on CITES Appendix II means any international trade in wild-caught tegus is regulated to prevent exploitation. Many range countries have their own regulations. For example, Argentina has set hunting quotas or seasons in some provinces, and breeding farms exist to supply leather and pets under controlled conditions. Protected areas across South America (national parks, reserves) also provide safe habitat for tegus. In these areas, they benefit from overall ecosystem protection.

Interestingly, one “threat” related to tegus is not to them, but posed by them in places where they don’t naturally occur. In the United States (Florida and parts of the Southeast), escaped or released pet tegus have established invasive populations that threaten native wildlife (they eat eggs of ground-nesting birds and reptiles, for example). This has led authorities there to control tegu populations, but it’s a reminder of why responsible pet ownership and regulation are important. Within their native range, however, Argentine black and white tegus are doing well overall. Conservationists keep an eye on their status to ensure that hunting and trade do not escalate to unsustainable levels. At this time, the species does not require intensive conservation intervention, but continued monitoring and management of trade is important. The tegu’s stable status is a positive story, especially compared to many reptile species under threat, and it highlights the effectiveness of protections like CITES and sustainable use programs in keeping a species common and thriving.

The Argentine black and white tegu serves as an excellent educational ambassador for several reasons. Firstly, its dramatic black-and-white appearance and large size draw visitors’ attention, providing a great opportunity to engage people who might not otherwise be interested in lizards. Zoo educators can use the tegu to introduce the public to reptile biology – for example, demonstrating how cold-blooded animals regulate temperature. In the tegu’s case, we can even talk about that extraordinary partial endothermy, which often surprises visitors and leads to discussions about what being “warm-blooded” means. This helps dispel the notion that all reptiles are simple or primitive; the tegu is a living example of complexity in reptiles.

Tegus also allow educators to discuss ecosystem roles and adaptations. As omnivores, they illustrate how one species can influence many parts of the food web – controlling pests (by eating insects and rodents), seed dispersal (through their fruit-eating), and predation (raiding nests of other animals). Visitors learn how tegus fit into their native environment and why every species has an important niche. Because tegus are often compared to monitor lizards (which people may have heard of, like the Komodo dragon), they provide a chance to talk about convergent evolution and biodiversity in different regions.

Another key educational aspect is responsible pet ownership and invasive species awareness. The tegu’s popularity in the pet trade, and its invasive populations in places like Florida, allow zoos to discuss the impact of releasing exotic pets into the wild. Seeing a live tegu, people can understand how a pet lizard could survive and breed in non-native environments, threatening local wildlife. This can foster conversations about why we should never release pets and support efforts to control invasive species. It’s a tangible way to connect a zoo visitor in, say, Michigan or New York to conservation issues in far-off ecosystems.

Additionally, the tegu can highlight conservation through sustainable use. Programs in South America manage tegu populations so that limited hunting for leather or meat can be done without endangering the species – an example of how humans can use wildlife resources responsibly. The fact that tegus are not endangered (Least Concern), yet still protected under international agreements (CITES II), is a nuanced conservation success story. Educators can explain how proactive management kept the tegu from becoming overexploited, unlike many other reptiles that suffered from the skin trade. This adds a layer of understanding that conservation is not always about saving critically endangered species; it’s also about keeping common species common.

From a more personal perspective, having a calm, friendly-looking lizard like a tegu in educational programs helps break down fears and misconceptions about reptiles. Many people who might be afraid of snakes or spiders find themselves warming up to a tegu when they see it behaving gently, maybe even lazily enjoying a tummy rub from a keeper. This positive experience can be transformative, fostering empathy for reptiles and a willingness to learn more about them.

Finally, the Argentine tegu is a reminder of the rich wildlife of South America. It provides a chance to talk about the Gran Chaco and Pantanal ecosystems where it lives, which are less famous than the Amazon rainforest but incredibly important. In doing so, the tegu becomes an ambassador not just for its species but for the conservation of those habitats and the diversity of life found there. Whether the lesson is about adaptation, ecological balance, or human impacts on nature, the Argentine black and white tegu captivates audiences and delivers the message that reptiles are an integral and fascinating part of our world.

Educational Importance

Fun Facts / Trivia:

Partial Warm-Bloodedness: The Argentine black and white tegu is one of the only reptiles known to be partially endothermic. During breeding season, they can raise their body temperature by up to 10°F above ambient levels. Essentially, a mild form of warm-bloodedness, which is extremely unusual for lizards. This helps with digestion and activity during cooler spring weather.
“Lagarto Overo”: Locally in Argentina, they are called “lagarto overo,” which means “freckled lizard” or “spotted lizard” in Spanish. They’re also known as the Argentine giant tegu or simply giant tegus. The species’ scientific name, Salvator merianae, honors Maria Sibylla Merian, a 17th-century naturalist who illustrated South American animals.
Escape Artist Tail: Like many lizards, tegus can drop their tail as a defense mechanism. If grabbed by a predator, the tegu will release a portion of its tail, which continues to wiggle, distracting the predator. Later, the tegu will regrow the tail, though usually shorter or with a slightly different texture. Meanwhile, the original tail piece gives the lizard a critical chance to escape.
Powerful Jaws and "Shell Crusher”: Tegus have very strong jaw muscles. A big male can crush hard-shelled prey like snails, turtles, or walnuts. Those big jowls on the males aren’t just for looks; they indicate strong jaw power. Tegus in captivity have been known to bite down on feeding tongs or cage wire and bend them! Always use feeding tongs and never fingers when offering food to a hungry tegu.
Impressive Sprinting: Despite their hefty build and short legs, tegus can run fast. When startled, they can suddenly sprint and even run on their hind legs.
Forked Tongue like a Snake: People often notice the tegu’s forked tongue flicking in and out. Tegus use this to smell their environment when they collect scent particles on the tongue and deliver them to the Jacobson’s organ in the roof of their mouth, much like a snake does. This helps them locate food that’s hidden, like fruit among leaf litter, a nest of eggs, or an animal in hiding.
Tame and Intelligent: Many consider tegus one of the most intelligent reptiles. They can recognize their keepers, learn routines, and commands. Tegus can be trained to respond to audible commands or with visual tools. They can also be litter-trained to some extent, often picking a particular spot in their enclosure to use as a “bathroom.” Their intelligence and temperament have earned them comparisons to domestic cats or dogs in the reptile world.
Burrowing Engineers: Tegus are excellent diggers. In the wild, they often dig extensive burrow systems used for sleeping and brumation. These burrows can be quite long and may have multiple chambers. When they abandon burrows, other animals like snakes, rodents, or smaller lizards often move in, so tegus inadvertently help create homes for other creatures.
Convergent Evolution with Monitors: Tegus look and behave similarly to monitor lizards like Komodo dragons and Nile monitors, yet they aren’t closely related. This is a case of convergent evolution where both evolved to fill a similar predatory niche on different continents. So a tegu is like South America’s answer to the monitors of Africa and Asia.
Cultural Note: In parts of rural South America, tegus are sometimes viewed as pests because they raid chicken coops for eggs. But they can also be beneficial since they eat rodents and venomous snakes. They have found their way into local folklore. Some tales suggest that tegus are immune to snake venom, likely because they readily kill and eat snakes. They’re also featured in Guaraní legends and are an animal that commands respect due to its bold nature.