Geometric Tortoise

The geometric tortoise is naturally restricted to the far south-western corner of the Western Cape Province, South Africa. It used to occur as far north as Piketberg, as far south as Gordons Bay and eastwards into the Breede River valley. The habitat type of geometric tortoise is known as the renosterveld, which is located at the extreme southwestern part of the Western Cape Province of South Africa. The renosterveld forms part of the Fynbos biome, a vegetation zone characterised by a Mediterranean climate. There is a fusion of heathlands and shrublands with beginning and ending points hard to distinguish. Shrublands can then be further broken down into strandveld, coastal renosterveld and intercoastal renosterveld. The geometric tortoise is able to have specific dietary preferences, adaptation to wet habitats and topographical factors to survival in the habitat. The distribution range of the geometric tortoise lies within a winter rainfall area, which has 350–600 mm annual precipitation. The agriculture utilisation and urban development of the renosterveld are the major factors responsible for the massive decline on the number of tortoises. The destruction of renosterveld reduced the habitat of geometric tortoises to less than 3% of its original size, which has only 4000-5000 hectares remaining. …

The geometric tortoise's diet consists mainly of the leaves, geophytes, flowers, and shoots of a wide range of indigenous fynbos and renosterveld plant and grass species. Some of its more common food plants include Crassula ciliata, Oxalis species, local geophyte species, such as Cyanella hyacinthoides, Babiana angustifolia and Lachenalia contaminata; as well as a variety of grass species such as Themeda triandra, Briza maxima, Cynodon dactylon, Ehrharta calycina, Pentaschistis curvifolia and Eragrostis curvula. A failure to have the full range of these, and other specific local plant species, means that the geometric tortoise soon dies when taken out of its natural habitat or kept in captivity. The specific diet, together with climate, humidity and soil differences, are the principal reasons why the species does not survive for long outside of its habitat. It also means that the geometric tortoise is restricted to south-western Cape alluvial fynbos and shale renosterveld vegetation types. The geometric tortoise consumes at least 14 plant species as food, which includes 64% of Aspalathus species, 60% of Oxalis species and 66% of Berkheya species occur in Swartland Shale Renosterveld. Since the distribution range of geometric tortoise lies within a winter rainfall area, the annual grasses, geophytes and other herbaceous taxa are important food items during winter. …