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Description:

This is the second largest African lizard. It has a stout body with powerful limbs and strong claws. The skin is tough and covered with small, bead-like scales. The head has an elongate snout and the nostrils are round and situated midway between the eyes and the end of the snout. The tongue is dark. The tail is much longer than the body and is laterally compressed with a low dorsal crest. Adults are greyish-brown to dirty olive-brown on top of the head and back, with scattered darker blotches and from 6-11 light yellow bands or spots on the body and 10-18 light crossbands on the tail. The limbs are spotted and the belly and throat are paler with black bars. Juveniles are beautifully patterned in black and yellow.

Biology and breeding:


The Nile monitor is common in major river valleys foraging for food in the marginal vegetation. It is an excellent swimmer using its long oar-like tail. It often basks on rock outcrops or tree stumps. In temperate regions it may hibernate communally in a large rock crack on a rocky cliff or koppie bordering a river. The diet is varied. Adults forage in fresh water pools for crabs and mussels, but will also take frogs, fish and bird and their eggs. They also excavate and eat the eggs from terrapin, sea turtle and unattended crocodile nests. Juveniles rarely enter deep water, but shelter in marginal reed beds where they hunt for frogs and insects. Adults' teeth are rounded and peg-like (ideal for crunching crabs) unlike the sharp recurved teeth of juveniles. When disturbed they dive into the water and swim underwater to the safety of the reed beds. If cornered they bite and lash the tail in defence like the Rock monitor. Crocodiles and pythons are major predators on adults. Their flesh is edible and the fat is used for tribal medicine. They are however, protected by Provincial legislation.

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After spring rains (August - September) the female excavates a hole in a living termite nest and lay 20-60 eggs (54-64 x 30-40 mm). This may take 2-3 days to complete. The termites then repair their nest and the monitor eggs develop inside it, incubated at a constant temperature and humidity. It may take up to a year before the young emerge, although in captivity (at 30C) they hatch in 129-175 days. The young (200-320 mm TL, 23-32 g) emerge together, digging themselves out of the rain-softened nest the following summer.

Habitat:

Rivers, pans and major lakes.

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Range:


Sub-Saharan Africa, extending along the Nile River to Egypt. On the subcontinent, it occurs through the eastern part of the region, extending along the Orange River to the Atlantic Ocean, Fish River Canyon into central Namibia and along the south coast to the Kromme River valley; absent from the W. Cape.

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