Gemsbok / Southern Gemsbuck / Southern Oryx

Oryx gazella (Linnaeus, 1785)

Photo: Doug Lee

IUCN Conservation Status:

Gemsbok, Beisa oryx, Fringe-eared oryx = Lower Risk, conservation dependent (LR/cd);
Scimitar-horned oryx = Endangered (EN);
Arabian oryx = Critically endangered (CR).
“Unicorn” – the legend originated in Egypt from the appearance of several individuals of the scimitar-horned oryx that have developed only a single horn; this was not the remaining of the consequence of a prior break-off of the other horn. Further more: sunset, red sand dunes and gemsbok are the most majestic features catching most peoples mind when hearing the phrase “Kalahari”. The name oryx originated from Greek and refers to horns like pick-handles; were as the name “gems” is a Dutch term used for the chamois antelope Rupicapra rupicapra of Europe, which has little resemblance to the gemsbok. 

Taxonomy

Classification

The genus is presently divided into four species and four subspecies of which only the gemsbok or southern oryx occurs naturally in South Africa.
The species are:
• the gemsbok or southern oryx Oryx gazella gazella of southern Africa
• the Angolan gemsbok O.g. blainei of Angola
• the Beisa oryx O. beisa beisa of north-eastern Africa
• the fringe-eared oryx O.b. callotis of central East Africa
• the scimitar-horned oryx O. dammah of northern Africa
• the Arabian oryx, also known as white oryx, O. leucoryx of Arabia and Iraq

Although recognised by the Rowland Ward trophy register, discrepancy exists still among taxonomists regarding the validity of the sub-speciation of the Angolan Gemsbok. There is also a dispute on the recognition of beisa as an species, rather than a subspecies. Genetic research has not yet confirmed the issue.

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Description

The gemsbok is a large antelope with exceptionally long, almost straight horns which are heavily grooved, elongated pointed ears, long tail with a thick brush of long black hair, and a dark face-mask. The snout are totally covered with white hair, this is in contrast to all other antelope having bare snouts. Skin colour is a fawn-grey with a dark band on the the spine, down the throat and along the lower flanks, and on the upper legs. The front quarters are larger than the hind.
• Angolan gemsbok is slightly smaller than the gemsbok and with white ears.
• Beisa oryx is more slender build, shoulder height 115-122 cm, mass 150-204 kg.
• Arabian oryx is white toned across the entire body, with dark feet and a face-mask, and is the smallest, shoulder height 80-90 cm, mass 65-70 kg.
• Scimitar-horned oryx is white toned, with a faint brown face-mask, but has white legs and is reddish-brown around the neck and throat, shoulder height 110-125 cm, mass 180-200 kg.

Comparison To Man

Trophy

Horns are present in both sexes and are long, 38-42”, almost straight, heavily grooved with smooth ends. The horns of the cow are longer, but thinner, and usually narrower with a lesser tip-to-tip diameter, than that of the bull. Best trophies are generally found with cows. Horn buds are 2-3 cm long at 6 weeks age, and reach Rowland Ward trophy status after 6.5 years with cows and after 8 years with bulls.

Habitat requirement

Sandy soil, short annual sweet grasses (2-6cm), perennial broadleaved forbs, dwarf shrubs, low density large shrubs, and an annual rainfall of 50-300 mm. These conditions are mainly associated with dry, karroid scrubland, semi-desert shrub-vegetation, semi-arid open savannah as found in the Kalahari-sandveld, and arid grassland. Thicket and closed woodland are used only for refuge. Frequent disturbance by humans tend to transform gemsbok in becoming bush-dwellers. Moist drainage lines on especially alluvial and clay soils, tall grasses and forests are totally avoided. Gemsbok does not hesitate to roam steep, dry mountain slopes. They are not dependent on surface drinking water. Gemsbok cope with intensified heat of the day by rising its body temperature with 4° to 42°C. It is a poor jumper, but a master in crawling underneath fences.

Distribution

Feeding & Nutrition

Most activity takes place in early morning, late afternoon and deep into the night. During hot daylight hours they stand ruminating either in the sun or in shade. It is a partly selective mixed feeder of both grass and browse, consuming large quantities of roughage that are rich in fibre when surface drinking water is available. Without drinking water they become highly selective. The diet consists of 70-85% grass and broadleaved forbs and 25-30% browse from low growing shrubs. Succulents, tsamma-melons, gemsbok-cucumbers and digged out bulbs and roots are important sources of moisture in winter. Grasses taller than 30 cm and sourveld is unsuitable

Territory & Home range

Gemsbok groups are nomadic and will cover great distances wondering at random across large areas without following any fixed route. Thus can home ranges not be defined, nor the sizes be calculated. They will roam the entire area within the boundaries of any given farm or fenced land-unit, therefore a minimum land-area size of 1 200 ha is recommended for the keeping of gemsbok.
Adult bulls have large fixed territories of 420-890 ha (mean 760 ha), which are poorly demarcated. The boundaries tend to follow terrain morphological structures such as drainage lines, hills and koppies, dunes etc. Stranger solitary bulls rarely enter the territory and bull-fights are unknown. The inhabitant sporadically leaves its territory temporarily to join a passing mixed group that wonders across several territories, only to return to its territory at a later stage. At any given time of the year only 13% of the dominant bulls will be found single and within their own territories.
Territorial bulls defecate in a specialized manner of heeling down on the hind legs reducing the distance of fall of the dung. This behaviour results in the pellets dropping in a small compact pile that retains the odour for much longer than would it be spread out from a high fall, as with the standing cows who do not heel. Before defecating the bull scratches the soil with the front feet to translocate the secretions from the inter-digital glands between the hoofs. Some times they intentionally break branches and shrubs with the horns to demonstrate their dominance over the area.

Social structure

Gemsbok are predominantly semi-gregarious forming
• mixed groups of 5-40 individuals, which include several territorial bulls as temporarily associates, adult non-lactating cows, and subadult cows
• family groups of 4-12 animals, which include adult cows and calves and sometimes accompanied by a territorial bull
• bachelor herds of 2-7 bulls of all ages
• solitary territorial bulls

Photo: Doug Lee
During dry periods the groups split into smaller groups of 4-12 individuals, but congregate again when conditions become more favourable. Groups are unstable with poor family bonding, allowing for active exchange of individuals. In desert habitats groups tend to migrate after localised rains when temporarily aggregations of up to 300 gemsbok may occur. Groups are nomadic without any fixed home range.

Disease

Gemsbok are arid environment animals that developed evolutionary in absence of tropical diseases and parasites. Yet they also lack inter-animal contact and grooming behaviour that helps to eliminate external parasites. Therefore they can not tolerate high levels of parasite and tick infections. They are susceptive to both hartwater and lame-sickness, and especially to pneumonia during wet cold spells.

Information Table

Bibliography