Gemsbok (Oryx gazella)

Oryx gazella (common name Gemsbok) is a large antelope distributed in southwestern Africa, whose range has been considerably diminished (a) in the country of South Africa due to human overpopulation, habitat destruction and overhunting; and in (b) southern Angola from destabilizing warfare which occurred in the latter part of the twentieth century when Russia and Cuba sent in large numbers of troops in an attempt to destabilise the region.

This species is well adapted to the harsh arid and semi-arid environments of the region, with morphological dentition features enabling both grazing and browsing, and remarkable thermo-regulatory physiology that prevents dehydration in these environments. The total population of O. gazella is estimated at approximately 370,000 individuals.

Distribution and subspecies

Native distribution includes the majority of Namibia and Botswana, along with vestigial populations in southwest Angola and extreme northwestern South Africa. The range was much more extensive in western South Africa and southern Angola even one century ago. The human population explosion in South Africa, with attendant habitat destruction, overhunting and habitat fragmentation has decimated most of the native population in that country. In Angola, more recent warfare surrounding the Russian financed Cuban mercenaries, with attendant neglect of wildlife conservation in the latter part of the twentieth century has created considerable species decline.

The majority of the native range is populated by O. gazella gazella, the Kalahari gemsbok; however, the Angolan population is generally considered to be the subspecies O. gazella blainei, the Angolan gemsbok.

There are non trivial introduced populations of O. gazella in western Zimbabwe (Wilson & Reeder. 1993) and in the White Sands Missile Range, New Mexico in the USA.

Morphology

Oryx gazella is a sizable bovid exhibiting a thick, muscular neck, overlain by dense, inelastic skin. O. gazella is, in fact, the most massive species within the genus Oryx. This antelope stands 1.15 to 1.25 meters high at the shoulder, and presents a tail to nose tip body length of 1.80 and 1.95 meters, with males being slightly larger than females. The female body mass ranges from about 178 to 225 kilograms, while the male body mass is from approximately 180 and 240 kilograms.

Gemsboks have the ability to increase their internal body temperature as high as 45 degrees Celsius, as a mechanism to cope with high environmental temperatures and as a means of coping with evaporative water loss in its arid habitats. Tissues in its large nose present a means of cooling this large animal, by exposing a large area of veined tissue to the surrounding air.

The dentition of O. gazella is well adapted to cropping the short tough desert grasses, with a wide row of incisors and high crowned molars. (Archer & Sanson. 2002)

Habitat

Preferred habitat for this antelope is semi-arid and arid desert, bushveldt and grassland, including harsh environments of the Kalahari and Namib Deserts. (World Wildlife Fund & Hogan. 2012) O. gazella may be found on stony plains, sand dunes, rocky slopes and alkaline flats. It may travel considerable distances to drink from springs and visit natural salt deposits or salt licks. The typical altitude range of this species is from approximately 800 to 1300 meters above sea level.

This herbivore chiefly consumes its food by grazing, but during the dry season their palette is broadened to include a greater fraction of browse vegetation such as acacia pods. Adapting to arid environments has involved the ability to consume water rich foods such as bulbs, roots, tubers and tsama melons. (Sponheimer et al. 2003) The subsurface varieties of these foods it acquires by skillful excavation. (SSC Antelope Specialist Group. 2008)