Nile monitor

800px-Nile_Monitor,_Lake_Manyara

Profile

The Nile monitor lizard is a rather large lizard living in most of Africa. Adults are colored a lot the same as juveniles, but the younger ones have brighter colors. All ages have brown or black scales with yellow markings. This individual is a juvenile. You can tell this because of the vibrant yellow and the alternating black and yellow stripes on the lizard’s tail. Adults don’t have these stripes. Nile monitors are powerful, yet relatively slender animals. Their middle body (the part in between their pairs of legs) is not much wider than the rest of their body. There are 78 total monitor lizard species including the Nile monitor. This number may be increased in the near future as sub-species turn into species.

What’s in a name?

There are two theories on how monitor lizards got their name. The first is from their ability to stand on their hind legs and monitor their territory. The other suggestion is that the name came from the lizards habit of monitoring female crocodiles so they can steal the crocodile eggs to eat when the nest is left unguarded. The monitor lizard genus (Varanus) is derived from the Aarabic word “waran” meaning “monitor.” Nile monitor lizards are sometimes called water monitors. In South Africa they are called “water leguaan.” The word “leguaan” translated from Afrikaans means “iguana.”

Size

Adult water monitors typically grow to four feet (1.2 m) long. They can be much longer, however. Maximum size is controversial, and reports range from 6 feet (1.8 m) to 7.5 feet (2.2 m). Nile monitors can weigh up to 150 pounds (70 kg). Males and females are about the same size. This species of monitor lizard is the largest lizards in Africa.

Habitat and range

Nile monitor lizards are primarily aquatic, so they live in areas near rivers. As you can see on the map below, they only inhabit areas near rivers. They do not live in most of northern Africa because this area is covered almost completely in the Sahara desert. There is an exception around the Nile River. Africa is a land of many different habitats, and given the large percentage of this land Nile monitors inhabit, it is evident that they call many habitats home. Swamps, forests, grasslands, lakes, and rivers all are possible places to find these animals. Almost any place near a constant water place is reasonable Nile monitor habitat.

Nile_monitor_(varanus_niloticus)_distribution_map

Diet

Nile monitor lizards are carnivorous, they eat mammals, birds, snakes, lizards, toads, insects, snails, and carrion. As you can see, they are not very picky. They will also consume crocodile eggs as I mentioned earlier. Sometimes they will work together to steal the eggs, as one lizard draws the female crocodile away from her nest and the other digs up and steals the eggs. Juveniles do not have the teeth necessary to tackle some of the larger, harder prey, so they eat mainly insects. Even a snail’s shell presents too much of a challenge for the youngsters.

Status and threats

The Nile monitor lizard is not listed by the IUCN Redlist yet, but CITES has it listed on Appendix II. This means that it is not threatened with extinction, but there is moderate concern about its future population stability. They are hunted for their meat and skin, but still remain relatively common throughout their range. As of 1985, international trade of this species was banned, but they are sometimes still sold as pets. This is not recommended due to their large size and the doubts about their future in the wild. Although some people have released their pet Nile monitor into the wild after it got too big to handle, there are no known invasive populations anywhere in the world. The Denver Zoo has a Nile monitor that was found roaming around in Wyoming. It was probably abandoned by its owner once they realized how big it could get.

There are only a few natural predators of the Nile monitor lizard. The most common of these are crocodiles and pythons. Although juveniles are the most common Nile monitors to fall prey to other animals, adults are also sometimes eaten by predators.

Reproduction and young

Throughout their whole range, Nile monitor breeding season runs from June to October. Males take part in violent wrestling matches to decide mating rights. Females will lay their eggs after the rainy season has ended. The months in which this happens change depending on on the area. The eggs, up to 60 of them, are laid either in a hole the female digs or in an active termite mound. Although this probably isn’t the place you would want your kids to be, it evidently works out for the Nile monitors. The eggs take up to one year to hatch, and the young either climb out after rain has softened the dirt, or the female will return in time to dig out her young. Nile monitors can live up to 20 years.

Don’t forget to scroll down and comment your guess about what the next animal is!

800px-Four_Giant_Otters

Sources:

Photo credits:

  • Nile monitor – D. Gordon E. Robertson
  • Nile monitor range map – Maximilian Dörrbecker
  • Mystery animal – ww.Araguaia.org

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One Response

  1. African Fish Eagle
    African Fish Eagle at |

    […] of the adults, but eggs and young can fall prey to animals such as snakes, monkeys, baboons, and nile monitors. Just as these birds steal food from other birds, animals such as the tawny eagle sometimes steal […]

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