Nile Monitor

Nile Monitor Summary

“The Nile Monitor is the world’s fourth-largest lizard!”

The Nile monitor is one of the largest lizards on the planet, averaging 4 to 7 feet long and weighing anywhere from 13 to 44 pounds. Its body is large and muscular, with a long, heavy tail, a long, bulky neck, and a large head with sharp, pointed teeth. Its scaled skin is typically dark greyish-brown with many small, yellowish-green spots. Meanwhile, the throat and underbelly are off-white to yellowish in color. The species is a skilled predator and well-adapted for both aquatic and terrestrial lifestyles, and it feeds on a wide range of animals, including birds, rodents, reptiles, and mammals.

Nile Monitor Facts

• The Nile monitor is well-equipped for both aquatic and terrestrial habitats. It is commonly known as the water monitor and is a skilled swimmer, using its bulky tail as a rudder while swimming!
• Nile monitors can hold their breath and stay underwater for up to 15 minutes at a time.
• Though they are native to Sub-Saharan Africa, Nile monitors are invasive in south Florida.
• Nile monitors are very speedy on land and can run up to 18 miles per hour.
• In captivity, a Nile monitor can live for 15 to 20 years.

Nile Monitor Scientific Name

The Nile monitor’s scientific name is Varanus niloticus. Though experts once considered it to be a species complex, the West African Nile monitor and the ornate monitor (now Varanus stellatus and Varanus ornatus, respectively) are now distinct enough to be considered their own unique species.

Nile Monitor Appearance

As the longest lizards in Africa (as well as one of the largest), Nile monitors grow to anywhere from 3.5 to 7 feet long. However, some especially large specimens have been recorded measuring close to 8 feet in length. They can weigh up to 44 pounds. Their large, bulky tails are around 1.5 times the length of their bodies. They can use their tails to swipe at prey and give them better balance or as a flipper or rudder-like structure while swimming.

The Nile monitor’s overall body color varies from grayish-brown to olive green, and it is accented by numerous small, rounded yellowish splotches. Meanwhile, the lizard’s tail is similarly dark brown with large yellowish horizontal bands. Its neck is long and wide, making it capable of swallowing large eggs of various animal species whole.

Nile monitors have large, elongated, crocodile-like heads. Their nostrils sit high on their snouts, making them well-equipped for swimming for long periods of time. Their legs are also strong and wide, with large, sharp, thick claws ideal for tearing into prey and climbing trees. While juveniles have very sharp, pointed teeth, they become more dull and blunt as they age. Thanks to these traits, they are fast, strong, and skilled carnivorous predators.

Nile Monitor Behavior

Nile monitors are known to be high-energy and quite aggressive towards both prey and potential predators. Due to their speed, size, and considerable strength, they are essentially apex predators within their native range (as well as in areas where they are invasive like South Florida). Interestingly, they are sometimes kept as pets by reptile hobbyists despite their aggressive behavior.

As highly opportunistic predators, these massive lizards prey upon just about anything they can get into their sharp-toothed mouths. They feed on birds, frogs, mammals of varying sizes, turtles, snakes, lizards, and many species’ eggs and young. They stalk and often ambush their prey, fighting fiercely using every adaptation at their disposal. This includes their strong, sharp claws, teeth, and even their enormous tails to swat at and disorient their prey. 

In addition to being skilled swimmers, Nile monitors are also great at climbing trees and rocky terrain. They sometimes pounce on their prey at lightning-fast speeds, tearing into smaller animals with their claws and teeth. If they feel threatened, they will retreat to the closest body of water. True to their name, they tend to stay close to water.

Nile Monitor Habitat

The Nile monitor is native to Sub-Saharan Africa, particularly in eastern Africa along the Nile River’s banks. Though they can tolerate hot, dry conditions quite well, they do not inhabit desert habitats and prefer to stay near water. They enjoy utilizing the Nile River’s waters to stay cool, as well as to locate prey and hide from potential threats, predators, and other, larger monitor lizards.

In addition to their native range, Nile monitors have been introduced to South Florida. According to the Florida Fish and Wildlife Conservation Commission, they are highly invasive in the area. They likely arrived in the area after being released by exotic pet owners into the wild. Alternatively, some individuals may have escaped their enclosures by using their strong claws and teeth. They primarily inhabit Palm Beach, Miami-Dade, and Lee counties, though they are currently widespread throughout the region.

Nile Monitor Diet

As extremely adept apex predators, Nile monitors feed on a wide range of animals and their young. They are generalist carnivores and highly opportunistic in nature. Some of the animals they prey upon include:

• Other, smaller lizards
• Snakes
• Frogs and toads
• Invertebrates
• Various species’ eggs and babies
• Mammals varying in size (from cats to animals as large as antelopes)
• Birds
• Carrion
• (Rarely) Human and animal waste

Nile Monitor Predators and Threats

As apex predators, very few animal threats to the Nile monitor currently exist. It is unknown exactly how many individuals exist in the wild. However, they are a “least concern” species according to the IUCN Red List. This is largely due to their widespread range, apex predator status, hardy nature, and long lifespan. 

The primary threats to the Nile monitor’s population are humans, specifically poaching and habitat loss due to increasing urbanization in Sub-Saharan Africa.

Nile Monitor Reproduction, Babies, and Lifespan

Nile monitors reach sexual maturity at around 2 to 3 years of age. They are largely promiscuous in nature, with males mating with numerous females within the same breeding season. Males will fight fiercely with one another for mates and to establish dominance over one another. 

Notably, they have one of the largest average clutch sizes of any reptile, laying at least 12 and up to 60 eggs at a time. Females dig large, expansive burrows in which they deposit their eggs. Sometimes, they will lay their eggs in termite mounds, which can help provide food for their hatchlings later. The eggs hatch within around 6 to 9 months, when the hatchlings dig their way out of their nests. The females often return to the nests to assist their young with finding food.

Nile Monitor Population

It is unknown precisely how many Nile monitors currently exist in the wild, both within their native range and in Florida where they are invasive. The IUCN Red List currently classifies them as of least concern. As apex predators, very few threats to the Nile monitor exist aside from humans and habitat loss. They are commonly poached in Africa for food and their skins. 

Additionally, Nile monitors often aggressively fight to the death when seeking out potential mates. Ironically, this makes one of the largest threats to their population themselves.

Nile Monitors in the Zoo

The Nile monitor is a popular attraction in zoos worldwide due to its impressive size and handsome coloration, as well as its fierce nature when feeding. Some of the zoos that include it in their list of animals are the Bronx Zoo, Dudley Zoo and Castle, and Canada’s Reptilia Zoo. 

Nile Monitor FAQ

Are Nile monitors venomous?

Nile monitors are considered to be venomous, as their saliva is full of harmful bacteria that can make their prey very sick. However, they are not known to actually secrete true venom.

Are Nile monitors dangerous?

Nile monitors are highly dangerous and aggressive apex predators. Their strong claws, sharp teeth, and muscular bodies make them extremely dangerous to both their prey and potential human aggressors.

Are Nile monitors good pets?

Although many reptile hobbyists do keep Nile monitors as pets, this is not recommended unless you are highly experienced and knowledgeable about reptiles. They require very large enclosures and large amounts of food and can be difficult to house due to their hostile natures.

Do Nile monitors swim?

Nile monitors are very skilled swimmers. They use their huge, muscular tails as paddle-like rudders while swimming. Furthermore, their nostrils are set high up on their snouts, making them well-adapted for swimming for long periods of time. They can also stay underwater for more than 15 minutes at a time!

How do Nile monitors hunt?

Nile monitor lizards are essentially ambush predators. They stalk and jump onto their prey, tearing into prey animals with their claws and teeth at high speeds.