Nile monitor (Varanus niloticus)

KingdomAnimalia
PhylumChordata
ClassReptilia
OrderSquamata
FamilyVaranidae
GenusVaranus (1)
SizeLength: up to 2 m (2)

The Nile monitor is listed on Appendix II of CITES (1).

The Nile monitor (Varanus niloticus) is not only Africa’s largest lizard but also one of the continent’s most voracious predators (3). Stout-bodied and powerful, this formidable reptile has an elongated snake-like head, sharp claws, and a long, compressed tail which it uses to great effect when under threat (3) (4) (5).

The tough, beady skin of the adult is greyish-brown with regular yellow spots arranged in distinctive bands down the head, body and tail. The colour patterning of juveniles is more vibrant, with dark black skin covered in bright yellow spots and blotches (3) (5).

The distribution of the Nile monitor extends through much of sub-Saharan Africa, from Senegal across to Somalia and down to northeast South Africa (2) (5) (6) (7). It also occurs along the Nile up into southern Egypt (2).

Given its colossal range, it is no surprise that the Nile monitor occurs in a wide variety of habitats, wherever there are permanent bodies of water (6). Although this excludes deserts, this species has been found in most other habitats including grassland, scrub, forests, mangroves, swamps, lakes and rivers (2).

With an almost insatiable appetite, the Nile monitor is renowned for eating just about anything it can overpower or find as carrion. Consequently, its diet includes everything from arthropods, amphibians and fish, to birds, small mammals and other reptiles (2) (3). Hunting strategies vary, but it is rare for the Nile monitor to shy away from a challenge, and it will even team up with other individuals to steal eggs from larger predators such as Nile crocodiles. While one monitor provokes a female crocodile away from a nesting site, another will dig up the unguarded eggs (2).

Propelled by its powerful tail, the Nile monitor is an excellent swimmer and can reportedly spend up to one hour submerged (2). Although largely aquatic, the mornings are often spent basking in the sun on rocky outcrops or sandy banks (3). On land, it walks with a sinuous swagger and will sometimes climb trees to bask, feed or sleep (2) (5). However, this species is more vulnerable on land and if threatened will normally do its best to avoid injury and will flee to the safety of deep water. When escape is not an easy option, it will boldly defend itself, using its hefty tail, sharp teeth and powerful claws to injure or frighten away the aggressor (2) (3) (5).

Following mating, which takes place at the end of the rainy season, the female lays up to 60 eggs (the largest clutch size of any lizard) in termite mounds or burrows (2) (3) (8). Under fairly constant temperature and humidity, the unattended eggs are incubated over a period of six to nine months before hatching (3). The brightly coloured hatchlings survive on a diet comprised of insects, spiders, snails and other small animals, and reach maturity after three to four years (2) (9).

Although the Nile monitor is exploited for its meat and skin, and to a lesser extent in the pet trade (10), it remains widespread and common (2) (4).

There are no specific conservation measures in place for the Nile monitor but it is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) which makes it an offence to trade Nile monitors without a permit (1).

For further information on reptile conservation see:

Authenticated (24/12/11) by Olivier S. G. Pauwels, Research Associate at the Royal Belgian Institute for Natural Sciences, Brussels, Belgium.
http://www.pauwelsolivier.com

  1. CITES (June, 2008)
    http://www.cites.org/
  2. Pianka, E.R. and King, D.R. (2004) Varanoid lizards of the world. Indiana University Press, Bloomington, Indiana.
  3. Capula, M. (1990) The Macdonald Encyclopedia of Amphibians and Reptiles. Macdonald and Co Ltd., London and Sydney.
  4. Burnie, D. (2001) Animal. Dorling Kindersley, London.
  5. Alden, P.C., Estes, R.D., Schlitter, D. and McBride, B. (1996) Collins Guide to African Wildlife. HarperCollins Publishers, London.
  6. Faust, R.J. (2001) Nile Monitors: Everything About History, Care, Nutrition, Handling, and Behavior. Barron’s Educational Series, Hauppauge, New York.
  7. The Reptile Database (December, 2011)
    http://reptile-database.reptarium.cz/species?genus=Varanus&species=niloticus&search_param=%28%28taxon%3D%27Varanidae%27%29%29
  8. Pianka, E.R. and Vitt, L.J. (2003) Lizards: windows to the evolution of diversity. University of California Press, Berkeley.
  9. Bennett, D. (2002) Diet of juvenile Varanus niloticus (Sauria: Varanidae) on the Black Volta River in Ghana. Journal of Herpetology, 36(1): 116-117. Available at:
    http://www.anu.edu.au/BoZo/Scott/PDF%20Files/Byrne.JH.2002.pdf
  10. Enge, K.M., Krysko, K.L., Hankins, K.R., Campbell, T.S. and King, F.W. (2004) Status of the Nile monitor (Varanus niloticus) in southwestern Florida. Southeastern Naturalist, 3: 571-582.