The Monitor Lizards of Southern Africa

Nile Monitor (Varanus niloticus)

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Family: Varanidae.

Length: 120-220cm.

Description: The lizard is black and yellow with an elongated head and a flat tail to aid in swimming. Juveniles are usually more vividly coloured than adults.

Distribution: The species is present in the eastern part of Southern Africa but it is also present along the Orange river all the way to the Atlantic ocean. The species reaches is southern-most  limit at Seekoei river, Eastern Cape and is thus not present in the Western Cape.

Habitat: Closely associated with water sources such as dams, pans and rivers where it can be found from 0-1600m above sea level.

Reproduction: Oviparous, a female can lay up to 60 eggs. females lay their eggs in live termite mounds and juveniles emerge from the termite mound 4-6 months later.

Diet:  Freshwater Crabs and  mussels, frogs, fish, birds and their eggs. Nile monitors are also known to eat the eggs of terrapins, sea turtles and crocodiles. Juveniles tend to stick to reed beds in shallow water where they hunt frogs and insects

Predators: Crocodiles and southern African pythons are among the main predators of the nile monitor.

Conservation concern: Common and widespread, no concern

Threat to humans: Non-venomous, but an adult may bite or thrash their powerful tail if they feel threatened.

Interesting facts: Africa’s largest lizard.

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Rock Monitor (Varanus albigularis)

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Family: Varanidae.

Length: 100-150cm.

Description: The rock monitor is smaller than the nile monitor. It has strong, stocky limbs and an large swollen snout. The tail is longer than the body and the body is dark brown/grey with dark blotches spread across the back. the juveniles are more vividly coloured than adults with a less pronounced snout.

Distribution: It is found throughout the savannah and semi-arid regions of the southern and eastern parts of Southern Africa. It is absent from western Western Cape and the southern Northern Cape.

Habitat: Closely associated with rocky outcrops where it tunnels underneath rock overhangs to create burrows. Also known to use abandoned animal burrows and climb trees.

Reproduction: Lays 8-50 eggs in soft soil.

Diet:  Mainly invertebrates but will hunt and eat animals small enough to swallow. Also eats carrion and baby tortoises.

Predators: The martial eagle is the main predator of adults.

Conservation concern: Common and widespread, no concern.

Threat to humans: Non-venomous, but an adult may bite or thrash their powerful tail if they feel threatened.

Interesting facts: If threatened, the rock monitor may eject its cloacal contents or sham death.

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Resources:

Bates, M.F., Branch, W.R., Bauer, A.M., Burger, M., Marais, J., Alexander, G.J. & de Villiers, M.S. (eds). 2014. (CD set). Atlas and Red List of the Reptiles of South Africa, Lesotho and Swaziland. Suricata 1. South African National Biodiversity Institute, Pretoria.

Branch, B. 1994. Snakes and other Reptiles of Southern Africa. Cape Town. STRUIK.

Branch, B. 2016. Snakes and other Reptiles of Southern Africa. Cape Town. STRUIK Nature.