Rock or White-throated Monitor Varanus albigularis
SVL 400-500mm; max. SVL 850mm, TL 1 750mm.
This very large, stout lizard has strong, stocky limbs and sharp claws. The skin is tough and covered with small, bead-like scales in 110-167 rows at midbody. The head has a bulbous snout, with the nostrils slit-like and nearer to the eyes than to the end of the snout. The tail is longer than the body and cylindrical at the base but compressed towards the tip. The back is dark gray-brown above, with 5-6 pale yellow dark-edged blotches. The top of the head and neck are dark brown. The limbs are spotted with pale yellow, and the tail is banded in dark brown and off-white. The belly is dirty yellow with scattered spots. Juveniles are more intensely marked, and despite the common name which refers to the white throat of adults, have blackish throats.
Biology and Breeding
This monitor lives in a tunnel that it digs under rock overhangs, or in a disused animal burrow, a hole in a tree or a rock crack. It is usually solitary and hibernates, semi-dormant in its retreat in winter. Its skin is usually dulled with dirt and grime, and sullied with patches of unshed skin. It is also well-adorned with ticks in the soft skin around the eyes, nostrils and limb joints. The diet consist mainly of invertebrates (millipedes, beetles, grasshoppers and land snails) although it will kill and eat any animal small enough to swallow and also scavenges on carrion; baby tortoises are frequently ateen. In defense it adopts a side-on posture and lashes its tail. It will bite and hold on like a bulldog; if held behind the head it usually ejects it cloacal contents, and finally it may sham death, hanging limp (but still keeping its eyes open). If this ruse works and it is releases, it scampers to safety at the first opportunity.
The martial eagle (wingspan 188-227 cm (6.17-7.45 ft) and ratel are main predators on adults.
It rarely tames in captivity and because of its size needs a large enclosure. The flesh is reported to taste like chicken, but this monitor is protected by Provincial legislation (CITES, Appendix 11). They are great wanderers and may have home ranges up to 28sq km.
Mating occurs in August-September. The female may occasionally lay her eggs in a live termite nest, as does the Nile monitor, or even in a hollow tree, but normally uses a hole dug in soft moist soil. She may dig several 'test holes' before selecting a suitable spot. In early summer (October-November) from eight to 51 eggs (53-61 x 35-39 mm, 32-46g) are laid, depending on the size of the female. The eggs hatch in 110-120 days in captivity (27C), but take much longer in the wild. Hatchlings measure 220-282mm TL and weigh 18-21g. Many clutches are eaten by the band mongoose.
Habitat & Range
Savannah and moister karroid areas. Through the Savannah and semi-desert regions of the subcontinent, but absent from W. Cape. Elsewhere, to the Savannah of East Africa.
Only the typical race occurs on the subcontinent. It has 137-167 midbody scale rows and white throat in adults. A poorly defined race, Va angolensis, from Angola and adj. NW Zambia, has large scales on the head and along the backbone, and retains the black throat in adults. It has only 110-138 midbody scale rows. A small species V. exanthematicus from the West African Savannah's has a more uniform color pattern, lacks the white throat, and has enlarged scales on the back on of the neck and only 75-100 midbody scale rows; it is now treated as a separate species.