Tortoises > Angulate tortoise

Angulate tortoise / Rooipensskilpad, Ploegskaarskilpad

click to enlarge click to enlarge

Chersina angulata

Size This is a medium-sized tortoise species in which males grow larger than females. Adult males grow to approximately 270 mm in carapace length, 110 mm in shell height and may reach a mass of just over 2 kg. Adult females may reach 215 mm in carapace length, a shell height of just under 100 mm and could weigh up to 1.8 kg. Exceptionally large angulate tortoises of up to 300 mm may be encountered, but interestingly, cannot always be sexed accurately.

Description Angulate tortoises have elongated, more or less convex shells which are never flattened, and with steep sides. The outstanding characteristic of angulate tortoise shells is the single gular or chinshield below the head. This is the only South African species which possesses a single gular shield; all the other species have a pair of widened gular shields, which never protrudes further than the head. There are five claws on the front feet with four on each hind foot. The colour pattern of these tortoises varies, but the normal pattern is light-brown and black. The vertebral scutes on the carapace usually have a dark centre surrounded by a light-brown border. The rest of the shield is dark-brown to black. Characteristically, each marginal shield on the side of the shell has a black triangle. The plastron or underside of the shell may be light-brown to pale yellow, but may be vividly coloured with yellow, orange or red, hence the common names: “rooipensskilpad” (=red-bellied tortoise) or “geelpensskilpad” (=yellow-bellied tortoise). Unconfirmed reports relate the colour of the plastron with its regional diet. Often, older specimens become uniformly brown-coloured and one can expect to find specimens in the Karoo with uniformly black carapaces.

Biology The angulate tortoise occurs in a variety of natural habitats ranging from the Succulent Karoo in the Northwest, to West Coast strandveld and Fynbos habitats in the South, to inland Karoo habitats in the southeastern parts of its range, as well as the Subtropical Thicket or Valley Bushveld in the East. It is therefore unlikely that it has specialised habits and may be viewed as a true generalist species. These tortoises may remain active throughout the year, except in winter when their activity would normally be lower. Courtship and breeding behaviour is usually observed during spring when males actively court females and defend their territories against other males. Males will actively engage in combat with each other and will use the protruding gular shield to fight and attempt turning each other over. Females will lay 2 to 6 eggs a year, usually 1 to 2 per occasion. Eggs laid in spring will usually hatch after the first winter rains in the winter rainfall region, but may take longer to hatch if laid in summer, autumn or during early winter. Their natural diet is varied and is representative of the region in which they occur. Relatively dense populations are found in coastal regions, with the densest-known population on Dassen Island off Yzerforntein on the West Coast.

Distribution Angulate tortoises occur in a broad coastal region from North of Alexander Bay (into Namibia), southwards along the West Coast to the southwestern Cape or Boland, and eastwards through the southern Cape to East London. Inland, populations extend into the Cederberg, Tankwa Karoo, the Little Karoo and the eastern Great Karoo. There is also a population recorded in the Karoo National Park.

Distribution in GCBC Angulate tortoises occur in healthy numbers virtually throughout the Greater Cederberg Region, especially in the coastal (Lambert’s Bay and Eland’s Bay) and lowland areas to the West, and valley bottoms, for example at Algeria, except perhaps in true mountain fynbos habitats. One will find them in the Tankwa Karoo to the East, as well as in the Maskam and Gifberg areas to the North.

Conservation status Angulate tortoises are classified as Protected Wild Animals by the Nature Conservation Ordinance No. 19 of 1974 (as ammended in 2000) and may not be collected, transported, or possessed in, or imported into or exported from the Western Cape Province without special permission. Nationally, healthy populations occur throughout their range and they are not regarded as threatened. However, local populations may be threatened by a specific threat such as the clearing of land for agriculture or development, or collection for the pet trade. Similar to all other terrestrial tortoises, they are listed internationally in Appendix II of the Convention on the International Trade in Endangered Species of Fauna and Flora (CITES); legislation which regulates the international trade in these animals.

Threats Habitat destruction through indiscriminate agricultural and urban development , illegal collection for the pet trade, and the killing of specimens for food are all threats that threaten healthy angulate populations throughout their range. Fire in natural habitats also kills many specimens. They also fall prey to many natural predators such as baboons, jackal, mongoose, badgers and predatory birds. Hatchlings may be captured and impaled on thorns by fiscal shrikes, and every year thousands of hatchlings fall prey to the ever-increasing Pied Crow population in the West Coast regions. Domestic dogs and motorists who deliberately run over tortoises on roads may be added to this list. For example, every year, many angulate tortoises die on the R27 regional road along the West Coast.

Current studies For many years this species was poorly studied, but recently, a suite of ecological and other studies on the angulate tortoises of the Western Cape had been performed by workers of the University of the Western Cape, as part of a collaborative research programme with the Western Cape Nature Conservation Board. These studies enable conservation agencies to compile well-informed strategies to conserve healthy natural populations.

 

 
Developed by Ricardo Davids - 083 505 4129