The Nile monitor is one of three non-Saharan African monitors that appear regularly in the pet trade and one of the least expensive. But this hardy reptile has a well-earned reputation for being difficult. Nile monitors can be so tough to handle that experts suggest keeping a well-stocked first-aid kit nearby for yourself.
The other two non-Saharan African monitors are the savanna and the white-throated monitor. Of these three, the Nile is the longest, but may be exceeded in actual bulk by the white-throated monitor. Nile monitors remain one of the least expensive varanids available. Nile monitors have been available in the pet trade for over the last 40 years.
There are two subspecies of Nile monitors, the common, Varanus niloticus niloticus, and the ornate, V. n. ornatus. The ornate Nile monitor is considered a full species by some researchers and is primarily a forest race, while the common Nile monitor ranges widely, occurring not only in forested areas, but in savannas, semi-arid lands, flood-plain, estuarine and even seashore habitats.
If given the right diet and ample living space, the Nile monitor is exceptionally hardy in captivity. As babies, they are tiny and look innocent and pretty. People often buy them on impulse. When it becomes clear how difficult they can be to keep, they are often given up. This is a tragedy because it is not easy to find an alternate home for the animal.
Although they are often smaller, adult Nile monitors can attain a fairly heavy-bodied 6.5 feet in total length. Females are often somewhat smaller. Hatchlings are slender and usually less than 10 inches long.
In the wild, this large, long-tailed, lizard is an opportunistic feeder, eating insects, small mammals, other lizards, crocodile eggs and babies, snakes, amphibians, baby tortoises and tortoise eggs, bird eggs, mollusks and carrion.
Captives are often fed a diet consisting almost exclusively of laboratory rodents. This is not a satisfactory diet. Offer variety, but especially a lot of insects (baby Nile monitors will avidly consume healthy, vitamin-dusted crickets and roaches; adults need a more varied diet).
Both adults and hatchlings have an olive-black to black dorsal coloration that is strongly patterned with light (often yellow) ocelli and flecks. The color is reversed ventrally, being light with dark markings on the belly. The limbs are strong and the claws are sharp. The powerful tail is long and keeled dorsally.
The common Nile monitor has a dark tongue (easily seen, for a monitor will protrude its tongue, as a snake does, to gather scents as it explores its surroundings) while the tongue of the ornate Nile monitor is quite pink. Counted from shoulder to hips, the common Nile monitor has a “busier” pattern (usually seven crossbands formed of light ocelli) of smaller markings than the ornate race. The dorsal pattern of the latter is usually of five crossbands formed of large and well-defined ocelli. Albino Nile monitors have occasionally been found.
Several other monitor species are of somewhat similar appearance and are available in the pet trade, but all are considerably more expensive. Hatchling Nile monitors are very slender but adults can be of heavy build.
The Nile monitor is a large, rather heavy-bodied, predatory lizard. Young specimens can climb well, but adults are not prone to indulge in arboreal endeavors. Wild Nile monitors bask extensively. This lizard has very strong jaws and sharp teeth, a formidable combination if you happen to be bitten. Additionally, the claws are sharp and the strong tail is used as a whip. As would be expected, wild-collected adults can be difficult to handle, but with persistence, some babies tame reasonably well.
Farmed baby Nile monitors are the best choice for pets. However, unless you are prepared to offer these large lizards the care and space they need as an adult, do not purchase one.
Sexually active male Nile monitors and females that are about to lay, or that have recently laid eggs, can be very aggressive and difficult to handle. Even if your monitor is very tame do not give it an opportunity to bite.
Proper Feeding Choices
Captive monitors are traditionally and routinely fed a diet of small rodents and baby chicks. On this diet the lizards soon become unnaturally obese and lethargic. This is probably no healthier for them than it would be for a human. It has recently been demonstrated that a diet of insects and other low fat animal protein is better than rodents for the long-term well being of Nile monitors.
Crickets, roaches, grasshoppers and king mealworms are all avidly eaten by these lizards and should form a large percentage of the diet, even of large monitors. Augment this with some prepared commercial monitor food (chicken and fish based), and some mice. If you happen to be raising your own mice, raise them on a low fat diet. It is probable that if mice constitute only 30 percent to 45 percent of your monitor’s diet, there should be no problem.
A sizable shallow container of fresh drinking and bathing water should always be present. This should be provided in a container that can’t be tipped and is very easily cleaned.
Fast growing babies and ovulating female monitors should be given a D3-calcium supplement twice weekly. For adult males, provide vitamin-mineral supplements at least once every 2 weeks.
Wild Nile monitors are alert and fast. They depend on fleeing rather than aggression to avoid predators but, if cornered, can be frighteningly defensive. They bite, scratch and whip painfully with their tail. Some hatchling Nile monitors may allow themselves to be gently handled, but many will bite and scratch energetically. They are usually more wary of approach from above than from the side.
It is likely that your Nile monitor will quickly learn to associate your presence with the introduction of food. Because of their large size, voracious eating habits, and unpredictable behavior, large Nile monitors should never be fed by hand. Always use long, very sturdy forceps for offering food to these lizards.
If well maintained, Nile monitors grow fast, and adult Nile monitors need more cage-space than many owners can allocate to them. When well cared for, a lifespan of 10 to 15 years is not an unreasonable expectation. Greenhouses and spare rooms can also be adapted as a monitor home.
Although a 7- to 10-inch long baby Nile monitor could, in a pinch, be kept in a 15-gallon terrarium, a larger cage is always better. An adult Nile monitor needs a cage at least 8 feet long by 4 feet wide by 4 feet high.
Crisscross the cage with sizable diagonal and elevated horizontal limbs (at least the diameter of the lizard’s body) and provide both a sizable but easily cleaned water container and a hidebox. Visual barriers offer the lizards a feeling of security that is important to them. Illuminate and warm one end of a secure and often used perch (this will not necessarily be the highest perch) to 95 to –100 degrees Fahrenheit with a full-spectrum UV-B-heat bulb. The terrarium’s ambient daytime temperature should be about 85 F. Provide a natural photoperiod. Nighttime temperatures can drop by a few degrees. A substrate of mulch (of some non-aromatic form) can provide ease of cleaning. Many monitors regularly defecate in their water receptacles. Be prepared to change this as necessary.