The blue wildebeest (Connochaetes taurinus), also called the common wildebeest, white-bearded wildebeest, or brindled gnu, is a large antelope and one of the two species of wildebeest. It is placed in the genus Connochaetes and family Bovidae, and has a close taxonomic relationship with the black wildebeest. The blue wildebeest is known to have five subspecies. This broad-shouldered antelope has a muscular, front-heavy appearance, with a distinctive, robust muzzle. Young blue wildebeest are born tawny brown, and begin to take on their adult coloration at the age of 2 months. The adults' hues range from a deep slate or bluish-gray to light gray or even grayish-brown. Both sexes possess a pair of large curved horns.
The blue wildebeest is a herbivore, feeding primarily on short grasses. It forms herds which move about in loose aggregations, the animals being fast runners and extremely wary. The mating season begins at the end of the rainy season and a single calf is usually born after a gestational period of about 8.5 months. The calf remains with its mother for 8 months, after which it joins a juvenile herd. Blue wildebeest are found in short-grass plains bordering bush-covered acacia savannas in southern and eastern Africa, thriving in areas that are neither too wet nor too arid. Three African populations of blue wildebeest take part in a long-distance migration, timed to coincide with the annual pattern of rainfall and grass growth on the volcanic soil short-grass plains where they can find the nutrient-rich forage necessary for lactation and calf growth.
The blue wildebeest is native to Angola, Botswana, Kenya, Mozambique, South Africa, Swaziland, Tanzania, Zambia, and Zimbabwe. Today, it is extinct in Malawi, but has been successfully reintroduced in Namibia. The southern limit of the blue wildebeest range is the Orange River, while the western limit is bounded by Lake Victoria and Mount Kenya. The blue wildebeest is widespread and is being introduced into private game farms, reserves and conservancies. So, the International Union for Conservation of Nature and Natural Resources rates the blue wildebeest as being of least concern. The population has been estimated to be around 1.5 million, and the population trend is stable. They are among the most specialized and successful of African herbivores and are dominant in plains ecosystems.
Description & appearance
The blue wildebeest exhibits sexual dimorphism, with males being larger and darker than females. The blue wildebeest is typically 170–240 cm (67–94 in) in head-and-body length. The average height of the species is 115–145 cm (45–57 in). While males weigh up to 290 kg (640 lb), females seldom exceed 260 kg (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 the wild, and 21 years in captivity. The oldest known captive individual lived for 24.3 years. 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 coloration at the age of 2 months. The adults' hues range from a deep slate or bluish-gray to light gray or even grayish-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. Further, the heavy build and disproportionately large forequarters give it a bovine appearance.
Distribution & habitat
The blue wildebeest is native to Kenya, Tanzania, Botswana, Zambia, Zimbabwe, Mozambique, South Africa, Swaziland, and Angola. Today, it is extinct in Malawi, but has been successfully reintroduced into Namibia.
Blue wildebeest are mainly found in short-grass plains bordering bush-covered acacia savannas in southern and eastern Africa, thriving in areas that are neither too wet nor too arid. They can be found in habitats that vary from overgrazed areas with dense bush to open woodland floodplains. Trees such as Brachystegia and Combretum spp. are common in these areas. Blue wildebeest can tolerate arid regions as long as a potable water supply is available, normally within about 15–25 km (9.3–15.5 mi) distance. The southern limit of the blue wildebeest stops at the Orange River, while the western limit is bounded by Lake Victoria and Mount Kenya. The range does not include montane or temperate grasslands. These wildebeest are rarely found at altitudes over 1,800–2,100 m (5,900–6,900 ft). With the exception of a small population of Cookson's wildebeest that occurs in the Luangwa Valley (Zambia), the wildebeest is absent in the wetter parts of the southern savanna country, and particularly is not present in miombo woodlands.
Three African populations of blue wildebeest take part in long-distance migrations, timed to coincide with the annual pattern of rainfall and grass growth on the volcanic soil short-grass plains, where they can find the nutrient-rich forage necessary for lactation and calf growth.The timing of the migration in both directions can vary considerably from year to year. At the end of the rainy season, they migrate to dry-season areas in response to a lack of drinking water. When the rainy season begins again a few months later, the animals trek back to their wet-season range. These movements and access to nutrient-rich forage for reproduction allow migratory wildebeest populations to grow to much larger numbers than resident populations. Many long-distance migratory populations of wildebeest existed 100 years ago, but currently, all but three migrations (Serengeti, Tarangire, and Kafue) have been disrupted, cut off, and lost. Food
The blue wildebeest is a herbivore, feeding primarily on the short grasses which commonly grow on light, and alkaline soils that are found in savanna 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 zebras 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.
In a study of the dietary habits of the wildebeest, the animals were found to be feeding on the three dominant kinds of grass of the area, namely: Themeda triandra, Digitaria macroblephara and Pennisetum mezianum. The time spent grazing increased by about 100% during the dry season. Though the choice of the diet remained the same in both the dry and the wet season, the animals were more selective during the latter. Reproduction
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 behavior. The activities of these sexually excited males may also stimulate the female to come into estrus.
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. During courtship, urination and low-stretch are common activities, and the male soon attempts to mount the female. A receptive female holds her tail to one side and stands still while copulation takes place. Matings 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, often rubbing her head on his torso and sniffing his penis. 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. Some calves leave their mother at about 8 months and form herds with other juveniles. In large female herds, 80% of the wildebeest offspring survive the first month, compared to a 50% survival rate in smaller herds.