Rock monitor

Taxonomy

First described by François Marie Daudin in 1802, V. albigularis has been classified as a subspecies of V. exanthematicus, but has since been declared a distinct species based upon differences in hemipenal morphology. The generic name Varanus is derived from the Arabic word waral ورل, which is translated to English as "monitor". The specific name albigularis comes from a compound of two Latin words: albus meaning "white" and gula meaning "throat".

The subspecies of V. albigularis are:

• White-throated monitor, V. a. albigularis
• Angolan white-throated monitor, V. a. angolensis
• Eastern white-throated monitor, V. a. microstictus
• Black-throated monitor, V. a. ionidesi (but may be synonymous with V. a. microstictus)

Description

Varanus albigularis is the heaviest-bodied lizard in Africa, as adult males average about 6 to 8 kg (13 to 18 lb) and females weigh from 3.2 to 5 kg (7.1 to 11.0 lb). Large mature males can attain 15 to 17 kg (33 to 37 lb). It is the second longest African lizard after the Nile monitor (Varanus niloticus). Varanus albigularis reaches 2 meters (6 ft 7 in) in total length (including tail), with its tail and body being of equal size. Mature specimens more typically will measure 0.85 to 1.5 meters (2 ft 9 in to 4 ft 11 in). The head and neck are the same length, and are distinct from each other. The bulbous, convex snout gives an angular, box-like appearance. The forked tongue is pink or bluish, and the body scales are usually a mottled gray-brown with yellowish or white markings.

Diet

V. albigularis are generalists, feeding opportunistically on a broad variety of prey in the wild. Tortoises make up a significant part of their diet, and are swallowed whole due to the hard shell. Otherwise, this species consumes very little vertebrate prey, eating primarily invertebrates, especially millipedes, beetles, molluscs and orthopterans. Millipedes for example form nearly a quarter of their diet; the monitors are apparently resistant to its poisonous secretions. They are not averse to occasionally scavenging the corpses of vertebrate prey, even those as large as vervet monkeys, which are sometimes torn to pieces by "death rolling" like a crocodilian prior to consumption. Live vertebrate prey other than tortoises are usually too fast to catch for these monitors, and therefore form very little of their diet. This contrasts with what is often a diet of mostly vertebrates in captivity, such as rodents or poultry.

Intelligence

An intelligent lizard, several specimens of V. albigularis have demonstrated the ability to count as high as six in an experiment conducted by Dr. John Philips at the San Diego Zoo in 1999. Philips offered varying numbers of snails, and the monitors were able to distinguish numbers whenever one was missing.

Geographic range

V. albigularis is found in Central Africa (Democratic Republic of the Congo/Zaire), Southern Africa (Namibia, Botswana, Republic of South Africa, Swaziland, Zimbabwe, Mozambique, Zambia, Angola), the African Great Lakes (Kenya, Uganda, Tanzania), and the Horn of Africa (Ethiopia, Somalia).

Habitat

V. albigularis is found in a variety of dry habitats, including steppes, prairies, and savannahs, but is absent from desert interiors, rainforests, and thick scrub forests.

Folklore

People living with the virus of HIV/AIDS in Yumbe-district of Uganda have been reported injecting themselves with the blood of rock-monitors, which they believe to be a cure for the virus. Many are reportedly discontinuing anti-retroviral therapy to pursue this anecdotal treatment.

As a result, V. albigularis is reported to have become an expensive item in the Ugandan black market, selling for more than 175 US$ each.