What Is a Water Monitor Lizard?

The water monitor lizard, or Varatus salvator, is a large reptile native to Asia, the Philippines, and New Guinea. It is one of the largest lizards in the world. A mature water monitor lizard can reach a length of more than 9 feet (2.7 meters) and weigh more than 100 pounds (45 kilograms), although the majority is around half that size. Coloration is mostly gray with black stripes and yellow spots. The tail is half as long as the body.

Water monitors are strong swimmers, capable of swimming great distances, and this is how they got their name. This has enabled the water monitor lizard to populate remote islands where it has been known to establish thriving communities. A water monitor lizard is carnivorous and will eat anything it can, feeding on rodents, birds, eggs, snakes, and carrion. It will also eat other lizards, fish, monkeys, small deer, and insects.

These lizards are prolific breeders. After mating, females lay eggs about four to six weeks later and produce clutches of about 15 eggs, laying a total of approximately 40 eggs every year. The larger a female grows, the greater number of eggs she is able to produce.

They make their nests in hollow stumps, termite mounds, and burrows. These locations provide the constant temperatures required for the developing embryos. The incubation time varies greatly, depending on the climate, location, and time of year, with the eggs taking anywhere from 75 to 300 days to hatch.

Young water monitor lizards have brighter yellow coloration that they lose as they mature. Males are larger and heavier than females. Both genders reach maturity by their second year and can sometimes reach 15 years old.

Water monitors are preyed upon by larger animals such as larger water monitors and crocodiles. The young water monitor lizard is also subject to predation by large birds. Generally, around 50% of the water monitors that hatch live long enough to reach maturity.

The water monitor lizard has strong arms with sharp claws that it uses to climb and dig. They are fast runners, capable of outrunning most humans. To escape predators, they will run, climb trees, swim, or hide underwater for up to 30 minutes. The lizards are most active in the early part of the day. A water monitor lizard always remains near water since its preferred method of fleeing its enemies is to jump in and either hide or swim away.