From Wikipedia, the free encyclopedia - View original article
Temporal range: Late Pleistocene–Recent
|A bluebuck on display in the Naturhistorisches Museum Wien.|
|Former range (in red)|
Temporal range: Late Pleistocene–Recent
|A bluebuck on display in the Naturhistorisches Museum Wien.|
|Former range (in red)|
The bluebuck or blue antelope (Hippotragus leucophaeus), sometimes called blaubok, is an extinct species of antelope, the first large African mammal to disappear in historic times. It is related to the roan antelope and sable antelope, but slightly smaller than either. It lived in the southwestern coastal region of South Africa savannas, but was more widespread during the last glacial. It was probably a selective feeder, preferring high-quality grasses.
Europeans encountered the bluebuck in the 17th century, but it was already uncommon by then. European settlers hunted it avidly, despite its flesh being distasteful, while converting its habitat to agriculture. The bluebuck became extinct around 1800. Only four mounted specimens remain, in museums in Vienna, Stockholm, Paris, and Leiden, along with some bones and horns elsewhere. None of the museum specimens shows a blue colour, which may have derived from a mixture of black and yellow hairs.
Eighteenth-century travellers provided contradictory descriptions of this species, perhaps because some were embellishing, while others had not actually seen it and were simply repeating hearsay - Peter Kolb in 1719 incorrectly described it as having a long goat-like beard and tail, straight horns like an oryx, and short ears. They did send some skulls and skins back to Europe. In 1967, Erna Mohr reported the four existing mounted blue antelopes vary from 102 to 116 cm (3.35 to 3.81 ft) at the shoulder. Adult bluebuck probably rarely exceeded 160 kg (350 lb). None of the four museum specimens shows any sheen of blue. The dark skin showing through the thinning fur of older animals may have caused the blue colours described by several authors or the mix of black and yellow hairs.
The total length of the bluebuck was 250–300 cm (8.2–9.8 ft) for the male, and 230–280 cm (7.5–9.2 ft) for the female. The shoulder height was 100–120 cm (3.3–3.9 ft). The skull length was 396 mm (15.6 in). Horn length was 50–61 cm (20–24 in). It weighed 160 kg (350 lb).
Like most antelopes, the bluebuck had six teeth along the cheek in each half of the upper and lower jaws. These formed two distinct series, three premolars immediately followed by three molars. Its remains can be distinguished from those of the roan by smaller molars and premolars, and from the sable by larger premolars, and a higher ratio of premolar row length to molar row length.
It had a relatively long, strong neck with a very short, underdeveloped mane, long white legs with dark bands on the anterior, and a long tail, up to the hock, with a dark, horse-like whisk. It had a long muzzle. Its ears were long and donkey-like, rufous and narrow-pointed, without the black tufts of hair found in the roan.
The long, scimitar-shaped horns inserted directly above the orbits, extending upwards at almost right angles to the skull, and then curving back gently, without any torsion, towards the shoulders. These horns were heavily ridged, with 20-35 rings up to the tip of the horn, comparable to the roan (20-50 rings). Its horns were more lightly built than those of the roan and sable, though, and slightly transversely compressed to the inside. The back-curved horns reminded Jan van Riebeeck of the European ibex, and he called it the steinbok. It remains uncertain how long this name was used, or when it was changed to blaauwbok or bluebuck.
Its hair was short and glossy, and of a delicate light blue to grey - which quickly faded to a bluish grey after death. Its belly was pale white, and did not actually contrast with the colour of the flanks. Its forehead and the upper muzzle were brown, becoming lighter towards the cheeks and upper lips. It had distinct white patches in front of the eyes not reaching the white muzzle.
The bulls resembled the cows up to the age of three years, after which they became paler (almost white) and developed larger, more curved horns; the horns of the cows were more or less of the same length, although thinner and 10-20% smaller. The calves younger than two months were light tan, with no or very indistinct markings.
When the Europeans settled in the Cape Colony in the 17th and 18th centuries, they found the bluebuck on the coastal plains of the southwestern Cape Province, east of the Hottentots Holland mountains. It was never very common, and was probably restricted to a grassland area of less than 4 000 km2 in the triangle formed by the towns of Caledon, Swellendam, and Bredasdorp, South Africa. Lieutenant W.J. St. John also recorded 'roans' of a bluish grey colour at Liebenbergsvlei (28º15’S, 28º29’E) near Bethlehem in the Free State Province on 28–29 July 1853, and it is now thought that he actually saw the last remnants of a relict population of bluebuck.
From archaeological and palaeontological evidence, the bluebuck had a wider distribution and was more common during the early Holocene epoch 10,000 years ago. At one time it could be found on the coastal plain of the Cape Province from Elands Bay in the northwest to Uniondale in the east. Researchers of the National Museum in Bloemfontein have found San (Bushman) rock paintings near Ficksburg and Golden Gate Highlands National Park, while Pleistocene deposits (100 000 to 10 000 years ago) confirm its existence at Rose Cottage cave near Ladybrand.
The early travellers found the bluebuck only in rolling grasslands with extensive marshes and open areas with perennial tuft grasses and little hillside scrub. It was also at home at higher elevations, up to 2 400 m above sea level. It was susceptible to droughts, and water was a necessary habitat requirement.
They avoided areas with short grass and woodland where trees formed a thick canopy or thickets. Habitat change, due to overgrazing of grassland by other species, such as sheep, thus threatened this species.
Like the roan and sable, it had to drink daily. Many other antelopes can obtain the moisture they need from the plants they eat and can go for long periods without drinking.
The bluebuck was a selective grazer of medium to long (0.5- to 1.5-m), perennial tuft grasses, such as high-quality red grass (Themeda triandra), spear grass (Heteropogon contortus), buffalo grass (Panicum spp.) and love grass (Eragrostis spp.). Unlike most other antelope, it was not particularly attracted to fresh grass, except during the dry season, when it would graze for short periods along drainage lines and on floodplains on the fresh growth following the yearly fires. However, like most grazers, it would probably browse during the dry season.
|This section does not cite any references or sources. (August 2009)|
Most of its activities took place during the day, especially early in the morning and late in the afternoon.
Bluebucks followed the conventional territorial system among the Hippotragini or 'horse antelopes': territorial bulls, herds of cows and calves, and bachelor herds which were kept segregated by the territorial bulls.
Bluebuck cows and calves lived in small to medium-sized herds of five to 20 individuals, but herds of 35 to 80 were not unusual. They normally occurred at a low density of about 4/km2. Cows shared a traditional home range, which included the territories of several bulls, and occupied it for up to 30 years. At very low densities in substandard habitats, the cows ranged across larger areas, and were accompanied by the same bull, which in the absence of resistance by territorial neighbours, defended a movable space around his own private harem.
Because they had long, dangerous horns, cows tended to be more aggressive than those antelopes whose females are hornless. Dominance hierarchies based on age and individual prowess were vigorously maintained by both sexes. Maternal herds, composed of animals with the same home range, were closed to outsiders. Herd members kept out of range of each other's horns, by increasing the individual space between them.
Herd composition changed daily and seasonally; members split into small groups during the rainy season, and concentrated into larger groups on the best available grazing near water during the dry season. The most cohesive groups were maintained by calves of different ages, which clustered around the youngest calf and usually lagged behind the herd.
Bulls were accepted in the natal herd up to the age of 15–18 months, which was unusually long. Until then, their similarity to cows suppressed the aggression of the territorial bulls. Subadult bulls were driven from the herd, and if they did not escape quickly enough, they were killed. They then joined bachelor herds, where they stayed until they reached five or six years of age, when they would be strong enough to defend their own territories.
The adult bull would advertise his presence and high social status by standing or lying alone or away from the herd, at a conspicuous place. The bull stood erect as a sign of high status, and it was self-advertising if it was not directed. When another bull approached his herd, the dominant bull would stand with his neck arched, head high, and ears turned sideways. Unless the intruder showed submission by lowering his head, the bull kept his ears erect, and waved his tail or tucked it between his legs, and a clash of horns and head-butting would take place. Its sound was a blowing snort.
One calf, with a birth mass of 12–14 kg, was dropped after a gestation period of 268–281 days at any time of the year, with a peak during late summer. Bluebuck are thought to have lived for up to 18 years.
The calves were vulnerable to attacks from spotted hyenas (Crocuta crocuta), leopards (Panthera pardus) and wild dogs (Lycaon pictus). The adults were large and formidable, and resistant to predation in areas with low predator densities. They did sometimes fall prey to lions (Panthera leo), but were attacked with caution. Normally, they would flee from predators, but when wounded, a bluebuck would lie down, preferably in a marsh, and defended itself with its razor-sharp horns - the angle-horn threat display indicating it intended to stab sideways or over its shoulder.
The bluebuck or blue antelope was the first large African mammal to become extinct in historical times.
Shortly after the last Ice Age, about 10 000 years ago, the bluebuck must have been common in the far south of Africa, which was largely covered with grassy plains. Numerous finds of subfossil bones indicate a former distribution area from Elands Bay in the present Western Cape to about 25°E at Uniondale, as well as in the eastern Free State. Bluebuck numbers dropped about 3 200-2 000 years ago, due to the change of grassland into bush and forest when the climate became warmer.
They showed a sharp decline around 400 AD, which coincided with the introduction of livestock, particularly sheep, by man at about that time. Competition for grazing with sheep, the resulting habitat degradation due to overgrazing, and diseases may all have contributed to a decline in bluebuck. Subsistence hunting could also have played a role. The Late Stone Age inhabitants of Rose Cottage cave are known to have hunted several game species, including bluebuck. To the San (Bushman), the bluebuck was an important animal, since rock art indicated these animals contained supernatural power.
Jan van Riebeeck mentioned a steinbok or ibex with back-curved horns near Cape Town, while the German Peter Kolb was the first to write about the existence of a blaauwbok or bluebuck in 1719. The bluebuck was clearly on its way to extinction when European naturalists and hunters finally discovered it. Its range was already small when Europeans who settled in the Cape Colony in the 17th and 18th centuries first saw this antelope. Swedish naturalist Carl Peter Thunberg noted in 1774 that these animals were becoming rare. European hunters and farmers hunted it mainly for its skin. Its meat was not fatty, and generally fed to the dogs, although it was just as tasty as that of deer. According to German zoologist Martin Lichtenstein, the last bluebuck in the Cape Province was killed in 1799/1800 in the Swellendam district. However,evidence suggests an isolated remnant population still existed further north in the 18th century, and the last bluebuck died in the eastern Free State more than 50 years later.
Cultivation of the Cape Colony and hunting with firearms quickly destroyed the last small herds. The bluebuck disappeared before the early natural history cabinets and museums had a chance to obtain a fair number of specimens.
The four mounted bluebuck skins are in the National Museum of Natural History “Naturalis” in Leiden (the Netherlands), and in the natural history museums of Stockholm (Sweden), Paris (France) and Vienna (Austria). Not counting the many bones excavated throughout the species' former range, there are two skulls, in Amsterdam (the Netherlands) and Glasgow (United Kingdom), and three pairs of horns, in Uppsala (Sweden), London (United Kingdom) and Cape Town (South Africa). None of these specimens is properly documented.
Two close relatives of the bluebuck are the roan antelope (H. equinus) and the sable antelope (H. niger). Although some naturalists in the past classified the bluebuck merely as a subspecies of the roan, it is now generally accepted as a separate species, because bluebuck and roan occurred in sympatry on the coastal plain of the southwestern Cape from Oakhurst to Uniondale during the early Holocene.
|Wikimedia Commons has media related to Hippotragus leucophaeus.|