Wildebeest (, ; , ,), also called gnu (, or , ), are antelopes of the genus Connochaetes and native to Eastern and Southern Africa. They belong to the family Bovidae, which includes true antelopes, cattle, goats, sheep, and other even-toed horned ungulates. There are two species of wildebeest: the black wildebeest or white-tailed gnu (C. gnou), and the blue wildebeest or brindled gnu (C. taurinus).
Fossil records suggest these two species diverged about one million years ago, resulting in a northern and a southern species. The blue wildebeest remained in its original range and changed very little from the ancestral species, while the black wildebeest changed more as adaptation to its open grassland habitat in the south. The most obvious ways of telling the two species apart are the differences in their colouring and in the way their horns are oriented.
In East Africa, the blue wildebeest is the most abundant big-game species; some populations perform an annual migration to new grazing grounds, but the black wildebeest is merely nomadic. Breeding in both takes place over a short period of time at the end of the rainy season and the calves are soon active and are able to move with the herd, a fact necessary for their survival. Nevertheless, some fall prey to large carnivores, especially the spotted hyena.
Wildebeest often graze in mixed herds with zebras, which gives heightened awareness of potential predators. They are also alert to the warning signals emitted by other animals such as baboons. Wildebeest are a tourist attraction but compete with domesticated livestock for pasture and are sometimes blamed by farmers for transferring diseases and parasites to their cattle. Illegal hunting does take place but the population trend is fairly stable. Wildebeest can also be found in national parks or on private land. The International Union for Conservation of Nature lists both kinds of wildebeest as least-concern species.
Etymology is Dutch for 'wild beast', 'wild ox' or 'wild cattle' in Afrikaans (bees 'cattle'). The name was given by Dutch settlers who saw them on their way to the interior of South Africa in about 1700 because they resemble wild ox. The blue wildebeest was first known to westerners in the northern part of South Africa a century later, in the 1800s.
Some sources claim the name gnu originates from the Khoekhoe name for these animals, t'gnu. Others contend the name and its pronunciation in English go back to the word !nu: used for the black wildebeest by the San people.
Classification Taxonomy and evolution The genus name Connochaetes derives from the Ancient Greek words , 'beard',. and χαίτη, 'flowing hair, mane'.. It is placed under the family Bovidae and subfamily Alcelaphinae, where its closest relatives are the hartebeest (Alcelaphus spp.), the hirola (Beatragus hunteri), and species in the genus Damaliscus, such as the topi, the tsessebe, the blesbok and the bontebok. The name Connochaetes was given by German zoologist Hinrich Lichtenstein in 1812.
In the early 20th century, one species of the wildebeest, C. albojubatus, was identified in eastern Africa. In 1914, two separate races of the wildebeest were introduced, namely Gorgon a. albojubatus ("Athi white-bearded wildebeest") and G. a. mearnsi ("Loita white-bearded wildebeest"). However, in 1939, the two were once again merged into a single race, Connochaetes taurinus albojubatus. In the mid-20th century, two separate forms were recognised, Gorgon taurinus hecki and G. t. albojubatus. Finally, two distinct types of wildebeest – the blue and black wildebeest – were identified. The blue wildebeest was at first placed under a separate genus, Gorgon, while the black wildebeest belonged to the genus Connochaetes. Today, they are united in the single genus Connochaetes, with the black wildebeest being named (C. gnou) and the blue wildebeest (C. taurinus).
According to a mitochondrial DNA analysis, the black wildebeest are estimated to have diverged from the main lineage during the Middle Pleistocene and became a distinct species around a million years ago. A divergence rate around 2% has been calculated. The split does not seem to have been driven by competition for resources, but instead because each species adopted a different ecological niche and occupied a different trophic level.
Blue wildebeest fossils dating back some 2.5 million years ago are common and widespread. They have been found in the fossil-bearing caves at the Cradle of Humankind north of Johannesburg. Elsewhere in South Africa, they are plentiful at such sites as Elandsfontein, Cornelia, and Florisbad. The earliest fossils of the black wildebeest were found in sedimentary rock in Cornelia in the Free State and dated back about 800,000 years. Today, five subspecies of the blue wildebeest are recognised, while the black wildebeest has no named subspecies.
Genetics and hybrids The diploid number of chromosomes in the wildebeest is 58. Chromosomes were studied in a male and a female wildebeest. In the female, all except a pair of very large submetacentric chromosomes were found to be acrocentric. Metaphases were studied in the male's chromosomes, and very large submetacentric chromosomes were found there, as well, similar to those in the female both in size and morphology. Other chromosomes were acrocentric. The X chromosome is a large acrocentric and the Y chromosome a minute one.
The two species of the wildebeest are known to hybridise. Male black wildebeest have been reported to mate with female blue wildebeest and vice versa. The differences in social behaviour and habitats have historically prevented interspecific hybridisation between the species, but hybridisation may occur when they are both confined within the same area. The resulting offspring are usually fertile. A study of these hybrid animals at Spioenkop Dam Nature Reserve in South Africa revealed that many had disadvantageous abnormalities relating to their teeth, horns, and the wormian bones in the skull. Another study reported an increase in the size of the hybrid as compared to either of its parents. In some animals, the tympanic part of the temporal bone is highly deformed, and in others, the radius and ulna are fused.
Characteristics of the species
Both species of wildebeest are even-toed, horned, greyish-brown ungulates resembling cattle. Males are larger than females and both have heavy forequarters compared to their hindquarters. They have broad muzzles, Roman noses, and shaggy manes and tails. The most striking morphological differences between the black and blue wildebeest are the orientation and curvature of their horns and the colour of their coats. The blue wildebeest is the bigger of the two species. In males, blue wildebeest stand tall at the shoulder and weigh around , while the black wildebeest stands tall and weighs about . In females, blue wildebeest have a shoulder height of and weigh while black wildebeest females stand at the shoulder and weigh . The horns of blue wildebeest protrude to the side, then curve downwards before curving up back towards the skull, while the horns of the black wildebeest curve forward then downward before curving upwards at the tips. Blue wildebeest tend to be a dark grey colour with stripes, but may have a bluish sheen. The black wildebeest has brown-coloured hair, with a mane that ranges in colour from cream to black, and a cream-coloured tail. The blue wildebeest lives in a wide variety of habitats, including woodlands and grasslands, while the black wildebeest tends to reside exclusively in open grassland areas. In some areas, the blue wildebeest migrates over long distances in the winter, whereas the black wildebeest does not. The milk of the black wildebeest contains a higher protein, lower fat, and lower lactose content than the milk of the blue wildebeest. Wildebeest can live more than 40 years, though their average lifespan is around 20 years.
Interdigital glands The wildebeest only has interdigital (hoof) glands in its fore legs. Analysis of chemical constituents from a free ranging blue wildebeest from Zimbabwe (Cawston Block) showed this gland contains cyclohexanecarboxylic acid, phenol, 2-phenylethanol, methyl cyclohexanecarboxylate , and six short-chain carboxylic acids.
Distribution and habitat Wildebeest inhabit the plains and open woodlands of parts of Africa south of the Sahara. The black wildebeest is native to the southernmost parts of the continent. Its historical range included South Africa, Eswatini, and Lesotho, but in the latter two countries, it was hunted to extinction in the 19th century. It has now been reintroduced to them and also introduced to Namibia, where it has become well established. It inhabits open plains, grasslands, and Karoo shrublands in both steep mountainous regions and lower undulating hills at altitudes varying between . In the past, it inhabited the highveld temperate grasslands during the dry winter season and the arid Karoo region during the rains. However, as a result of widespread hunting, the black wildebeest no longer occupies its historical range or makes migrations, and is now largely limited to game farms and protected reserves.
The blue wildebeest is native to eastern and southern Africa. Its range includes Kenya, Tanzania, Botswana, Zambia, Zimbabwe, Mozambique, South Africa, Eswatini and Angola. It is no longer found in Malawi but has been successfully reintroduced into Namibia. Blue wildebeest are mainly found in short grass plains bordering bush-covered acacia savannas, thriving in areas that are neither too wet nor too dry. They can be found in habitats that vary from overgrazed areas with dense bush to open woodland floodplains. In East Africa, the blue wildebeest is the most abundant big game species, both in population and biomass. It is a notable feature of the Serengeti National Park in Tanzania, the Maasai Mara National Reserve in Kenya and the Liuwa Plain National Park in Zambia.
Migration
Not all wildebeest are migratory. Black wildebeest herds are often nomadic or may have a regular home range of . Bulls may occupy territories, usually about apart, but this spacing varies according to the quality of the habitat. In favourable conditions, they may be as close as , or they may be as far apart as in poor habitat. Female herds have home ranges of about in size. Herds of nonterritorial bachelor males roam at will and do not seem to have any restrictions on where they wander.
Blue wildebeest have both migratory and sedentary populations. In the Ngorongoro, most animals are sedentary and males maintain a network of territories throughout the year, though breeding is seasonal in nature. Females and young form groups of about 10 individuals or join in larger aggregations, and nonterritorial males form bachelor groups. In the Serengeti and Tarangire ecosystems, populations are mostly migratory, with herds consisting of both sexes frequently moving, but resident subpopulations also exist. During the rutting season, the males may form temporary territories for a few hours or a day or so, and attempt to gather together a few females with which to mate, but soon they have to move on, often moving ahead to set up another temporary territory.
In the Maasai Mara game reserve, a non-migratory population of blue wildebeest had dwindled from about 119,000 animals in 1977 to about 22,000 in 1997. The reason for the decline is thought to be the increasing competition between cattle and wildebeest for a diminishing area of grazing land as a result of changes in agricultural practices, and possibly fluctuations in rainfall.