Photograph: Jaco Powell www.kalaharisafari.com
J du P Bothma
The blue wildebeest or brindled gnu differs from the migratory white-bearded wildebeest of the Serengeti Plains of Tanzania.
There are five subspecies of wildebeest in Africa but the is only a coat colour variation of the blue wildebeest and should be called a . The brindled wildebeest group was first described scientifically as in 1788 by Zimmermann. The blue wildebeest was originally thought to be a separate species when Burchell described it as in 1824, based on a specimen that had been shot near Klein Heuningvlei north-west of Kuruman in the Northern Cape province. Because only occurs in India the genus was renamed by Lichtenstein in 1812. Early travellers gave it the local name of . Fossil wildebeest are known from the early Pleistocene in Africa some 2,5 million years ago.
The coat colour of the blue wildebeest is silvery grey, sometimes with a brown tint. Under certain light conditions a blue wildebeest appears to be bluish-grey, hence its common name. The forequarters are heavy, with humped shoulders and deep necks that contrast with the slender legs. The head is massive and elongated and the chin has a distinct, long, black beard. The dark, brownish bars that occur over the neck and shoulders and extend to the middle of the back create the brindled appearance. There is a mane of long, black hair and a long black whisk at the tip of the tail. The juveniles and adult cows are browner and have more russet foreheads than the adult bulls. The young calves are fawn in colour over all but some with black faces are known.
The shoulder height of an adult bull is around 1,4 m and that of a cow 1,3 m. The body weights are 250 kg and 183 kg respectively. Both sexes have smooth horns, which sweep outward and slightly downward before rising upward to end in tips that point inward. However, the horns are heavier in the bulls than in the cows. The blue wildebeest has pedal (interdigital) glands on the front feet and large pre-orbital glands on the face.
The blue wildebeest occurs in two geographic regions that are widely separated, from south-western Kenya to northern Mozambique, and again from south-western Zambia to southern Africa. In South Africa, it was historically confined to areas north of the Orange River but has now been introduced widely in bushveld regions.
The blue wildebeest prefers savanna woodlands, and shade and water are vital. They migrate seasonally in the dry season when occurring on large areas to find better grazing, as do the white-bearded wildebeest on the Serengeti Plains, and follow recent rainfall in response to the sound of thunder. There is a habitat separation from the black wildebeest because the latter prefers open, moist, bunch-grass areas. The blue wildebeest never moves far from cover and water and often selects old lands and heavily grazed grasslands with a poor veldt condition index, while the black wildebeest prefers taller stands of grass. The blue wildebeest also avoids rocky grasslands and southerly aspects, while the black wildebeest prefers less rocky northerly aspects.
The blue wildebeest is a grazer of short, lawn-like grasslands. It selects fresh green sprouts after veldt fires and rarely eats grasses that are more than 150 mm tall, but the grass selection changes seasonally with availability. Nevertheless, browse forms 13 per cent of the diet. When feeding, a blue wildebeest is selective of plant parts. Where available in high-rainfall years in arid regions the blue wildebeest will eat large volumes of moisture-rich tsamma melons .
The blue wildebeest is gregarious and herds of thousands of animals can gather when migrating. The usual breeding herd consists of 20 to 30 females and their young, but in the Kruger National Park it is 13 animals. Territorial bulls occur and bachelor herds also form. The territorial bulls retain their territories throughout the year unless drought forces them away, while the bachelor herds remain on the fringes of the population. A territorial bull goes down on his knees to mark his territory by rubbing the tar-smelling secretions of the pre-orbital glands onto bushes, tree trunks or the ground. The pedal glands are used to demarcate areas where grazing has recently occurred and to help individuals to follow each other when moving about. During cool weather, the blue wildebeest is active for the entire day, but it is usually less active at night except on moonlit nights. It is water dependent and drinks nine litres of water per day at any time of the day, but especially in the morning, and prefers natural waterholes.
Both sexes become sexually mature when 16 months old but a bull will only breed once it has become territorial. The sex ratio in the wild is around 1.5 adult cows per adult bull. Mating occurs from April to June in the Lowveld but it is bimodal in KwaZulu-Natal. Oestrus synchronization is possible and may be influenced by the lunar cycle. The gestation period lasts 250 days, the calf weighs 16 to 22 kg at birth and runs with its mother within a few minutes of birth. It starts to nibble at grass when it is two weeks old, but only weans when it is eight months old. The horn buds appear when a calf is three months old and the horns remain straight for the first eight months of life before starting to curve outwards. A blue wildebeest population can increase rapidly but in the Kruger Park with its large carnivores the mean population growth rate is 13,4 per cent. During periods of high rainfall the grass sward can become so rank that it allows lions to kill blue wildebeest with ease. The life-span is around 18 years.
Management and utilisation
The blue wildebeest should not be stocked in the same area as rare tall-grass grazers, such as the roan and sable antelope, because it destroys their preferred habitat. It will cross-breed with an adult black wildebeest bull when there is no adult blue wildebeest bull in the population, or where there is only a single adult bull of either type. For extensive production, a sex ratio of 10 adult cows per adult bull is recommended. The blue wildebeest does not require electrified fencing.
The blue wildebeest can be captured in capture bomas with the aid of a herding helicopter. Adults can also be immobilised chemically with 4 to 5 mg of M-99 in combination with 100 mg azaperone and 8 to 10 mg of M-5050 as an antidote. When using A3080, a dose of 5 mg in combination with 20 mg of azaperone is recommended. Short-term tranquillisation requires 10 to 20 mg of haloperidol for an adult bull, 10 mg for an adult cow, 5 mg for a juvenile and 2 to 5 mg for a calf, while the long-term tranquillisation of adults requires 100 to 150 mg of perphenazine enanthate.
Bulls should be transported in individual crates under tranquillisation, while family groups of cows and young can be transported in mass crates with 0,9 m2 of floor space per animal and seven to eight animals per crate. In all cases the horns should be piped. An individual crate for a blue wildebeest should be 1,9 m long x 0,7 m wide x 1,8 m high.
When keeping blue wildebeest in temporary captivity, aggressive adult bulls and cows should be kept in individual pens while young animals can be kept with non-aggressive cows.
A crude stocking density is 0.5 Large Animal Units per blue wildebeest (2 blue wildebeest per Large Animal Unit) but a more refined stocking density is 1 Grazer Unit per blue wildebeest (1 blue wildebeest per Grazer Unit) and 1.21 Browser Units per blue wildebeest (0.83 blue wildebeest per Browser Unit).
Blue wildebeest meat is higher (22,28 per cent) in crude protein and lower (1,06 per cent) in lipid than beef and is being exported. The dressed carcass yields 104 to 157 kg of meat. The mean weight of an animal in a population is 180 kg and the mean live sale price of R2 907 per blue wildebeest in 2011 translates into R16.15 per kg. The mean live sale price of R2 156 per blue wildebeest in 2012, a reduction of some 28 per cent over that in 2011, translates into a low meat price of R11.98 per kg. The record price is R29 000.
Although being hunted as a trophy animal there is no sign of a loss of trophy quality over time in South Africa. Trophy-sized animals can be judged on the basis of the horn curve span relative to the length of the ears.
Rowland Ward: Minimum horn length: 28,500 inches (72,390 cm); longest on record: 34,250 inches (86,995 cm) collected by L de Villiers in 2003, although there are uncertain reports of a trophy of 36,000 inches (91,440 cm) possibly collected in Musina.
Safari Club International: Minimum horn points: 70; best on record: 94,750 points and collected by B Hennings in 1983.
South African Method: Minimum horn length: 28,000 inches (71,120 cm); longest on record: 31,875 inches (80,963 cm) and collected by S C J Botha in 1982.
Selected sources available from the editor