Size Males attain larger body sizes than females. Populations in the Namaqualand region attain significantly larger body sizes than elsewhere within the range of the species. Maximum snout-vent length recorded for males from Namaqualand is 139 mm and from elsewhere 109 mm. Maximum snout-vent length for females from Namaqualand is 110 mm and from elsewhere 100 mm.
Description The head is short and triangular, the body flattened dorso-ventrally and the limbs well-developed with long toes. The tail is slightly longer than the snout-vent length. The body is covered with small scales. On the dorsal body, enlarged spines occur scattered among the small scales. Clusters of spines also occur around the ear opening. There is a weakly-developed dorsal crest which extends onto the tail. In males the tail is laterally compressed posteriorly and the crest well-developed, while in females the tail is more cylindrical and the crest weakly developed. The eyes are large and bulging like that of a chameleon, with round pupils.
When they are displaying their territorial colours, particularly during the breeding season, adult males are olive-green to red-brown above, with dark maroon to black markings. A distinct whitish to orange-yellow vertebral line extends from the neck to the tip of the tail. The head and forelimbs are blue to a greenish-blue. The throat is intense purple-blue in colour. The tail is grayish-white to yellow, usually with dark cross-bands. Females and non-displaying males are mottled in tan, cream, silvery green, and dark-brown above making them difficult to spot on the lichen-coverd rocks. The belly is off-white and there is a bluish network on the throat. Breeding females may have orange-yellow flanks with scattered red blotches.
Biology The southern Rock Agama is probably the most well-known lizard in South Africa . This is because of its extensive range and the conspicuousness of the brightly coloured males perching on rocks and fence poles along roads. It is diurnal and mainly rock-dwelling. It may form dense colonies and both males and females maintain territories, but those of males are larger and may contain those of several females. It has a polygynous mating system and a dominant male will mate with several females within its territory. Females will mate with any male that gains access. A dominant male normally perches on the highest point in its territory and does a characteristic pushup display and head nodding when intruders come too close. When danger threatens it hugs the rock and its bright colours fade quickly so that it becomes camouflaged against the lichen-covered rocks. It can run at great speed over the rocks and also jump from rock to rock.
Many people believe that it is highly poisonous. A farmer in the Kamiesberg once told us that the Rock Agama is responsible for many deaths among his cattle, particularly calves. According to him the lizard will jump on the back of the calve from a rock and then bite the calve in the neck region. The calf will die within minutes. There are of course no poisonous lizards in southern Africa, in fact there are only two poisonous species in the world, occurring in North and South America. It is, however, true that the rock agama can inflict a painful bite, drawing blood, because it has two fang-like teeth in the upper jaw.
Its diet consists mainly of ants and termites, but it will also eat other invertebrates. It is oviparous and two clutches of 7-18 oval, soft-shelled eggs are laid in a shallow hole dug in damp soil, the first clutch during October-November and the second in January-February. Incubation takes 2-3 months.
Agamas are closely related to chameleons, as is obvious from their ability to change their body colour and from the way they use the tongue in feeding. The tongue is, however, much shorter than that of chameleons.
Distribution It occurs over the whole of South Africa, with the exception of the sandy areas of the Northern Cape and parts of the Northern Province, Mpumalanga, and Kwazulu-Natal.
Distribution in the GCBC Probably occurs throughout the Biodiversity Corridor.
Conservation status Not listed.
Threats None identified.
Current studies None.
Recent studies include:
Swart B.L. 2005. The phylogeography of the southern rock agama (Agama atra) in the Cape Fold Mountains. Unpublished M.Sc. thesis, University of Stellenbosch.