WILDEBEEST

Facts

Blue Wildebeest

The Blue Wildebeest exhibits sexual dimorphism, with males being larger and darker than females. The Blue Wildebeest is typically 170–250 cm (67–98 in) in head-and-body length. The average height of the species is 115–151 cm (45–59 in). Males typically weigh 170 to 410 kg (370 to 900 lb) and females weigh 140 to 260 kg (310 to 570 lb). A characteristic feature is the long, Black tail, which is around 60–100 cm (24–39 in) in length. All features and markings of this species are bilaterally symmetrical for both sexes. The average life span is 20 years in captivity. The age that Blue Wildebeest live to in the wild is debatable. They can travel up to 80 km (50 mi) in 5 days without drinking water, with average temperatures of 38 °C (100 °F) in peak times of the day.

This broad-shouldered antelope has a muscular, front-heavy appearance, with a distinctive robust muzzle. Young are born tawny brown, and begin to take on their adult colouration at the age of 2 months. The adults’ hues range from a deep slate or bluish-grey to light grey or even greyish-brown. The back and flanks are slightly lighter than the ventral surface and underparts. Dark brown, vertical stripes mark the area between the neck and the back of the ribcage, thus giving it the name “Brindled Gnu”. The manes of both sexes appear long, stiff, thick, and jet Black, the same colour as the tail and face. While the manes of the western and eastern White-Bearded Wildebeest are lank, those of the Nyassaland Wildebeest and common Wildebeest stick up. Scent glands, which secrete a clear oil, are present in the forefeet and are larger in males than females.

In terms of skull length, the smallest subspecies of the Blue Wildebeest is the western White-Bearded Wildebeest. It is also the darkest subspecies; the Eastern White-Bearded Wildebeest is the lightest race. Both subspecies possess a creamy white beard, whereas the beard is Black in both the Nyassaland Wildebeest and the Common Wildebeest. The longest muzzles are found in the Nyassaland Wildebeest, and the shortest in female Western White-Bearded Wildebeest.

Both sexes possess a pair of large horns, which are shaped like parentheses. These extend outward to the side, and then curve upward and inward. In the males, the horns can be 83 cm (33 in) long, while the horns of the females are 30–40 cm (12–16 in) long. Despite being an antelope, the Blue Wildebeest possesses various bovine characteristics. For instance, the horns resemble those of the female African Buffalo. Furthermore, the heavy build and disproportionately large forequarters give it a bovine appearance.

The Blue Wildebeest is mostly active during the morning and the late afternoon, with the hottest hours of the day being spent in rest. These extremely agile and wary animals can run at speeds up to 80 km/h (50 mph), waving their tails and tossing their heads. The Wildebeest usually rest close to others of their kind and move about in loose aggregations. Males form bachelor herds, and these can be distinguished from juvenile groups by the lower amount of activity and the spacing between the animals. Around 90% of the male calves join the bachelor herds before the next mating season. Bulls become territorial at the age of four or five years, and become very noisy (most notably in the western White-Bearded Wildebeest) and active. The bulls tolerate being close to each other and one square kilometre (0.39 sq mi) of plain can accommodate 270 bulls. Most territories are of a temporary nature and fewer than half of the male population hold permanent territories. In general, Blue Wildebeest rest in groups of a few to thousands at night, with a minimum distance of 1–2 m (3–7 ft) between individuals (though mothers and calves may remain in contact). They are a major prey item for Lion, Cheetah, Leopard, African Wild dog, Hyena, and Nile Crocodile.

Female calves will stay with their mothers and other related females of the herd throughout their lives. Female individuals in a herd are from a wide range of ages, from yearlings to the oldest cow. During the wet season, the females generally lead the herd towards nutritious areas of grasses and areas where predators can be avoided. This is to ensure that newborn calves have the highest chance of survival as well as gaining the most nutritious milk.

Bulls mark the boundaries of their territories with heaps of dung, secretions from their scent glands, and certain behaviours. Body language used by a territorial male includes standing with an erect posture, profuse ground pawing, and horning, frequent defecation, rolling and bellowing, and the sound “ga-noo” being produced. When competing over territory, males grunt loudly, paw the ground, make thrusting motion with their horns, and perform other displays of aggression.

The Blue Wildebeest is a herbivore, feeding primarily on the short grasses which commonly grow on light, and alkaline soils that are found in savannah grasslands and on plains. The animal’s broad mouth is adapted for eating large quantities of short grass and it feeds both during the day and night. When grass is scarce, it will also eat the foliage of shrubs and trees. Wildebeest commonly associate with Plains Zebra as the latter eat the upper, less nutritious grass canopy, exposing the lower, greener material which the Wildebeest prefer. Whenever possible, the Wildebeest likes to drink twice daily and due to its regular requirement for water, it usually inhabits moist grasslands and areas with available water sources. The Blue Wildebeest drinks 9 to 12 litres of water every one to two days. Despite this, it can also survive in the arid Kalahari desert, where it obtains sufficient water from melons and water-storing roots and tubers.

Male Blue Wildebeest become sexually mature at about 2 years of age, while females can conceive at 16 months if adequately nourished. Nevertheless, most females do not start to breed until a year later. The mating season, which lasts for about 3 weeks, coincides with the end of the rainy season. This means that the animals are in good condition, having been feeding on highly nutritious new grass growth, and the conception rate is often as high as 95%. The mating season, or rut, typically begins on the night of a full moon, suggesting that the lunar cycle influences breeding. At this time, testosterone production peaks in males, resulting in increased calling and territorial behaviour. The activities of these sexually excited males may also stimulate the female to come into oestrus. As they stake out their territories and compete for females, males exhibit rivalry. When they clash, they face up to each other with bent knees and exchange horn thrusts. Elaborate individual displays are made during their rivalry, and they may bellow, snort, and dig their horns into the ground. Once dominance has been established, each male attempts to lure the female into his domain. Mating may be repeated several times and may take place twice or more times within a minute. The male neither eats nor rests when a female is present in his territory, and during this time, the female keeps close to the male. While in season, a female may visit several territories and mate with several different males.

The gestation period is about 8.5 months, and between 80 and 90% of the calves are born within a 3-week time period. Female Wildebeest give birth in the middle of a herd rather than alone, and typically in the middle of the day. This allows time for the newborn to become steady on its feet before night falls and the predators become more active. Calves weigh about 19 kg (42 lb) at birth, and can usually stand on their own within a few minutes of birth. To escape predation, calves remain close to their mothers for a significant time, and may continue suckling until the next year’s calf is nearly due. Male calves leave their mother at about 8 months and form herds with other male juveniles. In large female herds, 80% of the Wildebeest offspring survive the first month, compared to a 50% survival rate in smaller herds.

Black Wildebeest

Black Wildebeest are sexually dimorphic, with females being shorter and more slender than males. The head-and-body length is typically between 170 and 220 cm (67 and 87 in). Males reach about 111 to 121 cm (44 to 48 in) at the shoulder, while females reach 106 to 116 cm (42 to 46 in). Males typically weigh 140 to 157 kg (309 to 346 lb) and females 110 to 122 kg (243 to 269 lb). A distinguishing feature in both sexes is the tail, which is long and similar to that of a horse. Its bright-white colour gives this animal the vernacular name of “White-Tailed Gnu” and also distinguishes it from the Blue Wildebeest, which has a Black tail. The length of the tail ranges from 80 to 100 cm (31 to 39 in).

The Black Wildebeest has a dark brown or Black coat, which is slightly paler in summer and coarser and shaggier in the winter. Calves are born with shaggy, fawn-coloured fur. Males are darker than females. They have bushy and dark-tipped manes that, as in the Blue Wildebeest, stick up from the back of the neck. The hairs that compose this are white or cream-coloured with dark tips. On its muzzle and under its jaw, it has Black bristly hair. It also has long, dark-coloured hair between its forelegs and under its belly. Other physical features include a thick neck, a plain back, and rather small and beady eyes.

Both sexes have strong horns that curve forward, resembling hooks, which are up to 78 cm (31 in) long. The horns have a broad base in mature males, and are flattened to form a protective shield. In females, the horns are both shorter and narrower. They become fully developed in females in the third year, while horns are fully grown in males aged four or five. Scent glands secrete a glutinous substance in front of the eyes, under the hair tufts, and on the forefeet. Females have two teats. Apart from the difference in the appearance of the tail, the two species of Wildebeests also differ in size and colour, with the Black being smaller and darker than the Blue.

The Black Wildebeest can maintain its body temperature within a small range in spite of large fluctuations in external temperatures. It shows well-developed orientation behaviour towards solar radiation, which helps it thrive in hot, and often shadeless, habitats. Individuals may live for about 20 years.

Black Wildebeest are mainly active during the early morning and late afternoon, preferring to rest during the hottest part of the day. The animals can run at speeds of 80 km/h (50 mph). When a person approaches a herd to within a few hundred metres, the Wildebeest snort and run a short distance before stopping and looking back, repeating this behaviour if further approached. They communicate with each other using pheromones detected by flehmen and several forms of vocal communication. One of these is a metallic snort or an echoing “hick”, that can be heard up to 1.5 km (1 mi) away. They are preyed on by the Lion, Spotted Hyena, Cape Hunting Do, Leopard, Cheetah and Nile Crocodile. Of these, the calves are targeted mainly by the Hyena, while Lion attacks the adult.

The Black Wildebeest is a gregarious animal with a complex social structure comprising three distinct groups, the female herds consisting of adult females and their young, the bachelor herds consisting only of yearlings and older males, and territorial bulls. The number of females per herd is variable, generally ranging from 14 to 32, but is highest in the densest populations  and also increases with forage density. A strong attachment exists among members of the female herd, many of which are related to each other. Large herds often get divided into smaller groups. While small calves stay with their mothers, the older ones form groups of their own within the herd. These herds have a social hierarchy, and the females are rather aggressive towards others trying to join the group. Young males are generally repelled by their mothers before the calving season starts. Separation of a young calf from its mother can be a major cause of calf mortality. While some male yearlings stay within the female herd, the others join a bachelor herd. These are usually loose associations, and unlike the female herds, the individuals are not much attached to each other. Another difference between the female and bachelor herds is the lesser aggression on the part of the males. These bachelor herds move widely in the available habitat and act as a refuge for males that have been unsuccessful as territorial bulls, and also as a reserve for future breeding males.

Mature bulls, generally more than 4 years old, set up their own territories through which female herds often pass. These territories are maintained throughout the year, with animals usually separated by a distance around 100–400 m (330–1,310 ft), but this can vary according to the quality of the habitat. In favourable conditions, this distance is as little as 9 m (30 ft), but can be as large as 1,600 m (5,200 ft) in poor habitat. Each bull has a patch of ground in the centre of his territory in which he regularly drops dung, and in which he performs acts of display. These include urinating, scraping, pawing, and rolling on the ground and thumping it with his horns – all of which demonstrate his prowess to other bulls. An encounter between two bulls involves elaborate rituals. The bulls approach each other with their heads lowered, resembling a grazing position (sometimes actually grazing). This is usually followed by movements such as standing in a reverse-parallel position, in which one male urinates and the opponent smells and performs flehmen, after which they may reverse the procedure. During this ritual or afterwards, the two can toss their horns at each other, circle one another, or even look away. Then begins the fight, which may be of low intensity (consisting of interlocking the horns and pushing each other in a standing position) or high intensity (consisting of their dropping to their knees and straining against each other powerfully, trying to remain in contact while their foreheads are nearly touching the ground). Threat displays such as shaking the head may also take place.

Black Wildebeest are predominantly grazers, preferring short grasses, but also feeding on other herbs and shrubs, especially when grass is scarce. Shrubs can comprise as much as 37% of the diet, but grasses normally form more than 90%. Water is essential, though they can exist without drinking water every day. The herds graze either in line or in loose groups, usually walking in single file when moving about. They are often accompanied by cattle Egret, which pick out and consume the insects hidden in their coats or disturbed by their movements.

Male Black Wildebeest reach sexual maturity at the age of 3 years, but may mature at a younger age in captivity. Females first come into oestrus and breed as yearlings or as 2-year-olds. They breed only once in a year.

A dominant male Black Wildebeest has a harem of females and will not allow other males to mate with them. The breeding season occurs at the end of the rainy season and lasts a few weeks between February and April. When one of his females comes into oestrus, the male concentrates on her and mates with her several times. The pair usually separates after copulation, but the female occasionally follows her mate afterwards, touching his rump with her snout. During the breeding season, the male loses condition, as he spends little time grazing.

The gestation period lasts for about 8.5 months, after which a single calf is born. Females in labour do not move away from the female herd and repeatedly lie down and get up again. Births normally take place in areas with short grass when the cow is in the lying position. She stands up immediately afterwards, which causes the umbilical cord to break, and vigorously licks the calf and chews on the afterbirth. In spite of regional variations, around 80% of the females give birth to their calves within a period of 2–3 weeks after the onset of the rainy season – from mid-November to the end of December.

The calf has a tawny, shaggy coat and weighs about 11 kg (24 lb). By the end of the fourth week, the four incisors have fully emerged and about the same time, two knob-like structures, the horn buds, appear on the head. These later develop into horns, which reach a length of 200–250 mm (8–10 in) by the fifth month and are well developed by the eighth month. The calf is able to stand and run shortly after birth, a period of great danger for animals in the wild. It is fed by its lactating mother for 6–8 months, begins nibbling on grass blades at 4 weeks, and remains with the mother until her next calf is born a year later.