Oryx gazella (Linnaeus, 1758)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 646-647

141.

Gemsbok

Oryx gazella

French: Gemsbok / German: Sudliche Oryx / Spanish: Oryx de El Cabo

Other common names: Southern Oryx

Taxonomy. Capra gazella Linnaeus, 1758 ,

“ India.” Restricted by Thomas in 1911 to South Africa.

Gemsboks from Angola, Namibia, and the Kalahari are in general very much alike, but there is some evidence that those from the Nata River, north-eastern Botswana, are unexpectedly small, with small teeth and less spreading horns, which may represent undescribed subspecies. This species is considered monotypic here.

Distribution. The arid zone in Namibia, most of Botswana and the Northern Cape of South Africa, extending marginally into Zimbabwe, the Western Cape, the Eastern Cape, the North West, and the Free State of South Africa; formerly also SW Angola but now possibly extinct.

Descriptive notes. Head-body 180-195 cm (both sexes), tail 48-52. 5 cm, shoulder height 120-125 cm (males) and 112 (females), ear 19-23 cm, hindfoot 51-52 cm; weight 200-240 kg (males) and 190-210 kg (females). Skull is larger than in the northeastern African species, and as in the Fringe-eared Oryx ( O. callotis ), the horns are thick and tend to diverge more than in other oryxes. The general color is pale fawngray; there is a short dark mane down the neck. The flank band separating the colored flanks from the white underside is very wide, 119-229 mm; anteriorly, it merges with the dark color of the upper segment of the forelegs, and posteriorly with that on the upper segment of the hindlegs. The dorsal stripe is also very wide (90-116 mm) and well marked; in juveniles, it is much narrower. It runs all along the back, broadening out over the croup, and then narrowing again toward the tail base. The lower segments of the limbs are white, with dark brown bands above the front hooves. The face is white, with a blackish patch between the horns. The black continues forward as a thin line, then broadens out to a triangular blackish patch over the muzzle; from the sides of the horns, a wide blackish band extends forward through the eyes to the lower jaw, joining up with the lateral angles of the muzzle patch. The black under the lower jaw continues down the throat, with an elongated dark tuft marking a small dewlap. Newborns are fawn-colored, and attain the adult color by 4-6 months of age. The horns are extremely long, 70-150 cm, ringed for about one-third of the length; the thickness of the base is about the same as in the Fringe-eared Oryx , 12-14. 5 cm, and they diverge even more widely, the tips being about 30-50 cm apart; they have the same number of rings as in the East African species, about 15-25. Diploid chromosome number is 56, differing from the Beisa Oryx ( O. beisa ) and the Fringe-eared Oryx in having a centric fusion between chromosomes 2 and 17. DNA sequences from the control region indicate that the Gemsbok is probably a sister species to all other oryxes. Dental formula is 10/3, C0/1,P3/3,M3/3(x2)=32.

Habitat. Open arid country, including dune country, open grassland, and bush savanna, and they penetrate savanna woodland to travel between more open areas.

Food and Feeding. Gemsboks eat mainly grass, preferably when green. Grasses make up about 90% of the diet (according to stable isotope analysis, the figure is about 81%), but they also eat dry grass and some browse, and dig up to 1 m deep for roots, bulbs, tubers, wild melons, and cucumbers. They also dig waterholes in dry riverbeds.

Breeding. There appears to be no restricted breeding season, although there may be calving peaks. Only dominant males herd females and mate with them. During courtship, the male and female circle each other close together, the female with her head low and ears back; she squats and urinates, he tests the urine, begins close following, performs the ritualized foreleg kicking called “laufschlag,” rests his chin on her rump, and nudges with his muzzle. Unlike related species of Hippotragus and the Addax ( Addax nasomaculatus ), but like other oryxes, Gemsboks perform laufschlag with the foreleg straight. Gestation is 8-5 months, with a postpartum estrus. Females become sexually mature at about two years. The newborn young spontaneously hides itself in a curled up position and joins the herd after 3—4 weeks, at which time the horns have begun to sprout. In the herd, suckling appears to be synchronized among all the females after the adults have rested and ruminated. Weaning occurs at about five months.

Activity patterns. Like all oryxes, Gemsboks amble and nod their heads up and down when walking fast, and move at speed with a flowing trot.

Movements, Home range and Social organization. Like other oryxes, the Gemsbok lives in mixed herds with some solitary males. In Central Kalahari Game Reserve, Botswana, the home range of females is 6-21-7 km? (average 12-7 km?®), which are apparently territorial, 10-16 km?*in Namaqualand (Northern Cape), territories are 4-2-9-8 km? but an old male ranged over 66-88 km®, returning repeatedly to the same places, as females do, and often remaining within less than 1 km?® for 3-10 weeks. Mean distance travelled in 24 hours is only 2: 6 km (females) and 1-6 km (males). When competing for access to the waterholes that they have dug in dry riverbeds, males take precedence over females. Territorial males may be spaced at 0-5-1 km intervals; these males may dominate, even fight and defeat, the males in mixed herds, and then mate with their females. Territorial males may also accompany the herds,at least until they enter another male’s territory.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Despite being widely hunted for the trophy value of their horns, they survive in good numbers over most of their current range. Population estimates available give a total population of 326,000, but actual numbers could be even higher. Overall population trend is increasing in private farms and protected areas. Free-ranging introduced populations exist in New Mexico, USA.

Bibliography. Ansell (1972), Estes (1991a, 1991b), IUCN/SSC Antelope Specialist Group (2008an), Skinner & Chimimba (2005), Sponheimer et al. (2003).

Figures

138. Beisa Oryx (Oryx beisa), 139. Galla Oryx (Oryx gallarum), 140. Fringe-eared Oryx (Oryx callotis), 141. Gemsbok (Oryx gazella), 142. Scimitar-horned Oryx (Oryx dammah), 143. Arabian Oryx (Oryx leucoryx)

Distribution. The arid zone in Namibia , most of Botswana and the Northern Cape of South Africa , extending marginally into Zimbabwe , the Western Cape, the Eastern Cape, the North West, and the Free State of South Africa ; formerly also SW Angola but now possibly extinct.