The Nile monitor (Varanus Niloticus) is found in sub-Saharan Africa. They adapt to a wide variety of habitats from tropical rain forests, woodlands, grassland, dry savannas, evergreen thickets, scrub, mangroves and swamps.
They are somewhat similar in both appearance and also habits to the asian water monitor (Varanus salvator) found in southeast Asia. They live always next to water sources, such as rivers, lakes, wetlands, pans or coastal areas.
These lizards have been found at elevations from sea level up to 1,600 m (5250 ft). They aren't found in desert areas, but some have adapted to live in human modified habitats such as towns, farms, and homesteads.
Together with many other species like the Burmese python (Python bivittatus), they are considered an invasive species in Florida, with a thriving population, which proves their adaptability. Here they represent a threat to native species like the threatened gopher tortoise or burrowing owls by eating their eggs and hatchlings.
They can reach over 2,5 meters long (8 ft), so they are the largest lizards in Africa. But they average about 1,4 to 1,6 meters in length. Usually, the tail usually measures a little over half the total length of the body.
Nile monitors exhibit no sexual dimorphism, males and females have similar sizes. These reptiles have a strong body, powerful legs with strong claws and long prehensile tail with a distinct dorsal crest.
They have a tough, beady skin brown, grayish-brown or olive green in color, with yellow spots distributed in a more or less regular banded pattern along the head, body, and tail. Their belly is yellowish with blackish cross-bands. Juveniles are usually more vibrantly colored with their dark blackish bodies being covered with bright yellow spots or blotches.
Like snakes, the Nile monitor has a snake like forked tongue, which serves, together with the Jacobson's organ, to obtain information about their surroundings. But they also appear to have good eyesight.
These diurnal reptiles are generally seen in on rocks or branches in the sun to keep warm since they are ectothermic animals like all reptiles. During the night they seek shelter in burrows totally excavated by themselves or by expanding existing animal burrows.
Nile monitors can remain underwater for more than an hour, they are excellent swimmers using their powerful compressed tail to propel them through the water. Sometimes they will climb trees up to 5 to 6 meters high to sleep, bask or even to hunt.
Adult specimens can even outrun a human on land, whilst over short distances. Even so, they are the most vulnerable on land, and when threatened will certainly try to escape fleeing to the relative safety of the water or down a hole, rock crevice or termite nest.
If escape it's not possible they will inflate the throat and hiss loudly, raising themselves up high to appear bigger. But if the attacker persists, Nile monitors will vigorously defend themselves using their powerful tails, sharp teeth and claws to scare the predator away.
While the Nile monitor has few predators they are hunted by other animals like the massive African rock python (Python sebae).Their lifespan is about 15 years in the wild. They are closely related to the mosasaur, a large, extinct sea monster that became extinct million years ago.
They also known by other common names including African small-grain lizard, water leguaan or river leguaan.In South African English leguan, leguaan, and likkewaan means monitor lizard.
Nile monitor - Diet
The Nile monitor has an almost insatiable appetite and it will eat just about any animal it can overpower, but they are also often seen plundering turtle nests or crocodile nests to feed on the eggs.
They feed on eggs of turtles and crocodiles, as well as amphibians, crabs, snails, frogs, fish, other reptiles, birds, and carrion.
The hatchlings feed almost entirely on insects and as they grow bigger start eating other animals. Land snails are one of the Nile monitor's favorite prey, using their powerful jaws to crush the hard shell.
The Nile monitor is a stealthy lonely hunter attacking its prey with lightning speed and killing it with a combination of crushing bites and severe injuries from its claws.
But on occasion, they have been observed working in pairs to raid crocodile nests. One lizard is used as a distraction for the female Nile crocodile guarding the eggs while the lizard goes in and grabs the eggs.
Nile monitor - Reproduction
It is an oviparous species and mates promiscuously. Reportedly Nile monitor males may fight each other violently in the mating season engaging in a kind of wrestling matches for the opportunity to mate.
In populations near the equator mating can occur at any time of year, but in southern regions of their area of distribution, mating usually occurs between June and July. The posture of the eggs is carried out approximately 30 days after mating.
The female lays 20 to 60 eggs on the banks of a river or inside a termite mound (which has, in this case, an essential role in maintaining the humidity and temperature). The incubation period lasts anywhere from only four months to ten months or even a full year.
Females may sometimes return to the nest just after the young hatch to open the nest and free the hatchlings. Juveniles emerge from the nest normally after the summer rains and resemble small versions of their parents.
Once they hatch the baby Nile monitors have to fend for themselves.They reach sexual maturity at about three years old.
Nile monitor - Conservation status and major threats
This species is not threatened globally (according to the International Union for Conservation of Nature). It belongs to the CITES Appendix II. Even so, the species is considered vulnerable in Egypt.
Some populations are endangered due to hunting for the leather industry and organs for traditional medicine. These monitors are also collected for the pet trade, although they make poor pets due to their size and aggressiveness.
Moreover, the construction of dams has increased the available habitat area, contributing to the increase of Nile monitor numbers in some places but their decline downstream.
Species: V. niloticus