The Nile Monitor is the largest species of lizard native to Africa in terms of overall length. They can grow to over 7 feet in length.
They have a very large distribution and can be found throughout much of sub-Saharan Africa. They can also be found along the Nile River Basin.
Nile Monitor Taxonomy
The Nile Monitor belongs to the Varanidae family of lizards. This family contains only one genus of living lizards. There are two extinct genera associated with this family, Ovoo and Saniwa.
The remaining genus, and the genus that the Nile Monitor belongs to is called Varanus. This is essentially the genus of Monitor Lizards, which are native to Africa, Asia and Oceania.
The closest living relatives to the lizards in the Varanus genus are the species in the anguid and helodermatid genera.
The lizards in the anguid genus are native to the Northern Hemisphere and include the glass lizards and the alligator lizards.
There are only 5 species of lizards in the helodermatid genus and they are all venomous. This family includes the Gila Monster.
Monitors are a large genus of lizard that contains over 80 different species at the time of writing. However, many species and sub-species are constantly being disputed so the exact number will change from time to time.
The group of Monitor lizards include some of the largest species of lizards in the world such as the Komodo Dragon and the Asian Water Monitor.
The genus name, Varanus is derived from the Arabic word ‘waral’ which simply translates into Monitor.
The scientific name for the Nile Monitor is Varanus niloticus. It was first described in 1758 by Swedish taxonomist Carl Linnaeus.
Linnaeus is credited for formalising binomial nomenclature which is the modern system of naming organisms. He has described a large number of reptiles including the Yellow Footed Tortoise, the Common Slow Worm, the Green Ameiva, the Eastern Copperhead, the Mediterranean House Gecko, the Northern Water Snake and the Banded Water Snake.He also described the Ringneck Snake, the Blunthead Three Snake, the Rainbow Lizard, the Greek Tortoise, the Surinam Horned Frog and the Desert Horned Viper.
The group of Nile Monitors found in Western Africa are sometimes referred to as a separate species, the West African Nile Monitor but this is still being disputed.
Nile Monitor Description
The Nile Monitor is the largest lizard in Africa in terms of overall length, with specimens capable of reaching over 7 feet in length, including their tail.
However, the majority of these monitors won’t reach this size and some won’t grow any larger than around 4 feet.
Despite being larger, they are not as heavy as some of the sub-species of Rock Monitor such as the Black Throat Monitor, with large adults typically weighing between 5-15kg.
They have a dark grey or brown base color that flares into a lighter tan or yellowish color along the sides and down onto their belly.
Their tail consists of a series of light and dark bands that start behind the legs and run all the way to the tip of the tail. It is also ‘paddle shaped’ which helps them swim.
The patterning on these lizards can vary greatly but typically consists of some form of rosette spotting. This is usually greenish or yellowish in color with dark spots in the middle.
Natural Habitat and Distribution
The Nile Monitor can be found throughout much of sub-Saharan Africa and along the Nile River Basin where there is plenty of fresh water.
These lizards can be found in almost every country in sub-Saharan. The only places you won’t find them is in the true desert regions.
These regions include the entire extent of the Sahara Desert but they are also absent from other desert and arid regions such as the Namib Desert and the Guban Desert around Somalia.
These lizards will live in a variety of different habitats but are primarily found around a fresh source of water such as a river or lake. But they may also be found around temporary sources of water.
They can be found in places such as Woodlands, Savannas, Scrublands, Swamps, and Mangroves.
Behaviour
The Nile Monitor is a terrestrial species that spends most of their time on the ground where they live in burrows.
However, they are excellent climbers and juveniles in particular can sometimes be found high up in the canopy where they can escape from predators.
These lizards are also excellent swimmers and are just as at home in the water as they are on land. They will often bask on overhanging trees. Then if a threat appears, they will drop off the branch and fall into the water to escape.
They are sometimes considered an aggressive species but this isn’t true. They would much prefer to be left alone and of startled will try to escape to the security of the water.
However, if they are cornered, they will try to defend themselves by hissing loudly and swinging their tail. If this doesn’t work, they may bite or emit a foul-smelling musk.
Nile Monitor Diet
The Nile Monitor will feed on a variety of different animals including rodents, lizards, birds, eggs, beetles, worms, slugs and caterpillars.
Some of the aquatic species they will feed on include fish, frogs, turtles, crabs and toads. They are even able to feed on poisonous toads.
They have a very powerful bite and are capable of crushing small prey with a single bite. However, for larger prey they will hold them in their jaws and tear at them with their sharp claws.