Black Wildebeest / White-tailed gnu

Connochaetes gnou (Zimmermann, 1780)

Photo: Sam Bash

IUCN Conservation Status:

Lower Risk, least concern (LR/lc)

This odd animal is certainly the most bizarre living antelope with the mane and tail of a horse, the face of a steer and the delicate legs of a buck. Its appearance is matched by its freaky behaviour. A phrase by W Cornwallis Harris (1840), read as follows, “A more whimsical compound than the Gnoo could scarcely have been thrown together, or a monster imagined of more fantastical and anomalous exterior”. The name ‘black” is misleading as the animal is a dark brown, while the name “white-tailed gnou”, which refers to the cream-white tail, is more relevant. “Gnu” is a Khoi-khoi word named after the animals’ alarm snort, a “ger-nu”.

Taxonomy

Classification

The tribe Alcelaphini evolved in Africa about 6 million years BP and includes the three genera Connochaetus or wildebeest, Damaliscus the blesbok and tsessebe and Alcelaphus the hartebeest. There are two species and four subspecies of wildebeest

• Connochaetes gnou the black wildebeest
• Connochaetes taurinus the blue wildebeest; subspecies
• C.t. taurinus the southern brindled gnu (blue wildebeest)
• C.t. cooksoni the Nyassa or Luangwa valley brindled gnu
• C.t. johnstoni the Mozambique brindled gnu
• C.t. albojubatus the East African white-bearded gnu.

The black wildebeest is endemic to South Africa and never existed elsewhere. Hundreds of thousands once roamed the open grasslands of the Free State and the Northern Cape Provinces, and lesser numbers in the central grasslands of most other provinces.

Description

A large antelope with a stiff, straight mane of long, pale-cream hair tipped with brown; a long white, horse-like tail; and the brush of brown, curly hair on the muzzle. The body is a dark yellow-brown that appears black from a distance. The face is darker in colour than the body. The back is hollow with both the shoulders and the buttocks at a higher level than the rump. A long beard stretches from the throat across the centre of the breast to the navel. Calves are a cream to light-brown at birth that continues to darken until an age of 18 months.

Comparison to Man

Trophy

Both genders have well-developed horns that have their origins in a thickened boss on the head and then extend forwards in a deep, downwards curve. The anterior halves of the horns are straight and then project vertically upwards with the tips bent slightly backwards. The horns of cows are thinner than those of the bulls and are thus lighter. Horn development is relatively rapid and trophy status may be reached at 2.5 years of age.

Habitat requirement

Open grassy plains, with short grasses and without trees and shrubs are preferred. The grass composition may be either a sweet or a mixed veld type but preferably not exclusively sour. Highveld areas and mountain plateaux’s are favoured, especially at an annual rainfall of 400-700 mm. Semi-arid and desert conditions and sub-tropical or tropical habitats are unsuitable. Forests, thickets, closed woodland, bushveld and wooded drainage lines are also generally avoided. If located in a habitat that is not optimal, black wildebeest will transform the structure of the herbaceous vegetation destructively by ploughing the soil with the horns and front hooves. Tall grass is not tolerated but new growth on recently burnt veld is a major attraction. Surface water for daily drinking is essential.

Distribution

Feeding & Nutrition

Most feeding takes place during the cooler daylight hours of the early morning and late afternoon. Hot midday hours are spend lying in open sunlight ruminating. Black wildebeest are exclusively grazers and highly selective of both the species of grass and its vegetative part. Artificial licks and supplementary, concentrated pellets are not easily accepted. The natural diet consists of between 63-93% short grasses below 6 cm of both sweet and sour species, 3-34% karroid dwarf shrubs and brush and 3% dicot forbs. Grasses above 12 cm are marginal to unsuitable.

Social structure

Black wildebeest are social gregarious animals. The structure of a population consists of:

• family groups of 10-60 individuals consisting of adult cows, heifers, post-mature cows and calves of both sexes
• bachelor groups of 10-30 individuals including sub-adult bulls of 1-3 years and non-dominant adult bulls
• territorial breeding bulls which are dominant and mostly solitary.

Adult cows maintain a hierarchy of female dominance that is mostly age related. The highest ranked female acts as group leader. Family bonds between cows and their female offspring are very tight and can last for life. Male calves of 12-14 months are chased from the herd by the dominant bulls as the herd moves through their territories. Post-mature bulls cast out from the herd usually reunite with bachelor groups. In absence of competition by developing bulls, a single territorial bull in an area will often attack heifers and calves aggressively out of frustration. They are area bound and will remain in the same home range as long as the veld condition remains suitable and sufficient, otherwise they will migrate over long distances. The adult body size is reached at 2 years.

As black and blue wildebeest crossbreed successfully, the two species should not be kept together on small management units or within the same habitat. In the wild however, the two species rarely interact due to their different habitat preferences. A manager must be constantly aware of the potential risk of crossbreeding. Nature Conservation authorities do not issue permits for keeping both species on the same management unit. Crossbreeds are known commercially as red wildebeest. Red wildebeest hybrids must not be confused with the recent commercially bred golden wildebeest, which is not a genetic hybrid but a colour variation of the blue wildebeest.

Diseases

Black wildebeest are commonly resistant to the majority of diseases. Exceptions are the larvae of the nasal butt-flies Kirkioestrus minentus and Oestrus variolosus, ocular-vascular myiasis caused by the larvae of the fly Gidoelstia sp. and malignant catarrhal fever. As the latter two diseases are highly contagious in domestic livestock, especially in cattle, both black and blue wildebeest must be separated from them by a corridor of at least 1 km. However malignant catarrhal fever is more commonly found in blue wildebeest with their sub-tropical origin, than in black wildebeest from the cooler temperate regions. Exposing black wildebeest to either blue wildebeest or to warmer sub-tropical conditions increases the risk of infection.

Information Table

Bibliography