Range

Africa is the native home of the nile monitor. Here they may be found across much of Sub-Saharan Africa avoiding the most arid areas. They can be found along the nile river up to Egypt. They venture South to South Africa and out to the Western and Eastern coastlines of much of the continent. Their total range comprises 33 countries.

An introduced population also exists in Florida likely from pets which have been released.

Habitat

Their wide range means they inhabit a number of habitats with the common factor in these being proximity to water such as a lake or river. They make their home in woodland, savanna, scrub, swamps and mangroves.

They will dig a burrow in which they live. They may also occupy another animal’s burrow with some small modifications.

Reproduction

Nile monitors breed at the end of the rainy season. Males will fight for the right to mate with the females and can mate with multiple females across the breeding season.

The female will deposit her eggs in to a burrow or in to a termite nest. They lay the largest clutches of any lizard with between 12 and 60 eggs being deposited.

Females give no further care to the eggs once they are laid unless they are laid in a termite mound. If this occurs she may return to free them once they hatch. If the mother does not return they will wait for rain which softens the nest and allows them to escape. They will incubate in their eggs for up to 9 months before hatching.

Young weigh 26g (0.9oz) at hatching. From day one they are independent and feed on insects and other small animals.

Sexual maturity is achieved at 3-4 years old.

Behaviour

Nile monitors emerge during the day to bask on a tree stump, river bank or rock. They require the heat from the sun to generate energy as an ectothermic animal.

They are a capable swimmer. When in the water they are able to stay submerged for up to an hour. On occasion they have been seen swimming out at sea.

In the Southern portions of their range the nile monitor will hibernate in a communal den or a crack in the rocks.

Predators and Threats

The nile monitor is preyed upon by crocodiles and pythons. Their strong tail is used to whip predators and their claws and teeth are used for further defense. Another defense mechanism is their ability to make foul-smelling musk come out of their cloaca.

Quick facts

Nile monitors have become popular pets but their large size often leads to them being abandoned and this has enabled the establishment of invasive populations.

In South Africa they are sometimes referred to as the “water monitor” or “water leguaan.”