Nile Monitor Fact File
The nile monitor is covered with bead like scales which are grayish brown, olive or black and these have bands of lighter colouring across their tail and the rest of the body along with speckles. At the base of the skull and along the neck are yellowish bands in a v-shape.
Their tail is long and strong which is used for swimming and defense. It tapers to a point at the top and this assists with swimming. The tail may be up to 1.5 times as long as the body. Their tongue is forked and used for sensing prey within their surrounds. They have strong front legs which end with sharp claws.
Males and females are similar in their appearance.
They are Africa’s largest lizard. They may measure up to 2m
(6.6ft) long and weigh up to 20kg (44lbs).
Nile monitors are a carnivorous species. They feed on crabs, molluscs, fish, frogs, birds, insects, smaller reptiles, eggs and carrion. On a rare occasion pairs have been seen working together to rob a crocodile nest with one distracting the mother crocodile while the other raids the nest.
They will feed on almost any animals which they are able to overpower. To catch prey they will jump on them with speed and then crush them with their strong jaw.
Wild 14.6 years
Captive 20 years
— AD —
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.
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.
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.
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.
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.”
Charles J Sharp / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
Muséum de Toulouse / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)
Burnie, D., 2011. Animal. 3rd ed. London: DK
Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley, p.226-227.
Florida Fish And Wildlife Conservation Commission. 2020. Nile Monitor. [online] Available at:<https://myfwc.com/wildlifehabitats/nonnatives/reptiles/monitors/nile-monitor/> [Accessed 14 June 2020].
Szczepaniuk, K. 2011. "Varanus niloticus" (On-line), Animal Diversity Web. Accessed June 13, 2020 at https://animaldiversity.org/accounts/Varanus_niloticus/