Lizards
Lizards belong to the sub-order SAURIA: this sub-order consists of typical lizards, skinks, agamas, geckos, chameleons and their relatives.
Many are highly specialized showing a variety of specific features.
Some species are legless and are often confused with snakes. In the legless forms, evidence of legs is still found.
The body is covered with granular scales which can be overlapping or not overlapping.
They usually have external ears and moveable eyelids.
Many lizards can shed their tails when in danger (autotomy). The detached part of the tail has many nerves causing the tail to wriggle. The intention is to distract the predator’s attention from the main body of the lizard and allow his/her escape. The tail will re-grow.
Skinks (Family scinicidae)
Physical features: the shiny, smooth scales of these reptiles are often brightly coloured. The legs are small, vestigial or, in some cases, there are no legs. Most skinks live above ground whilst a few are fossorial.
Food chain: they are secondary consumers: insectivores.
Defence mechanisms: they shed their tails to distract predators.
Breeding behaviour: skinks are both viviparous (Kalahari burrowing skinks) and oviparous (Kalahari tree skinks)
Monitor lizards (Family varanidae)
Physical features: Colour on the back and sides is grey with cream underbelly. They have strong, stout legs with long powerful claws and muscular, laterally compressed tails.
The long forked tongue is used as a sensory organ that is extended to pick up air borne particles and transfer this back to the Jacobson organ.
Defence: they cannot shed their tails but these can be used to inflict serious injuries to would-be predators. The larger specimens have powerful jaws.
They are diurnal (active during the day)
Breeding: they are oviparous (Nile monitor lay their eggs in termite mounds).
Two species are found in southern Africa and both of them occur in Botswana: the rock/white-throated monitor and the Nile/water monitor.
Nile monitor (water monitor lizard or leguaan).
Breeding: they frequently lay their eggs in termite mounds. During summer they dig a hole in the mound, lay their eggs and then leave, often without covering the hole. The termites close up the hole thus affording protection to the eggs as well as providing both thermo regulated environment and humidity. The young hatch and dig their way out of the mound.
Nile monitors have a varied diet including small aquatic vertebrates, bird’s eggs and chicks, aquatic invertebrates and crocodile eggs. They are a major predator of crocodile eggs and in some cases the main threat to crocodile populations in nature/game reserves.
White-throated monitors (rock or tree monitor lizard).
They lay eggs in rock cracks, abandoned animal burrows or cavities in trees. Their diet is varied from small vertebrates such as rodents, bird’s chicks and their eggs, other reptiles, frogs and various arthropods.