Springbok


The springbok or springbuck is an antelope found mainly in south and southwest Africa. The sole living member of the genus Antidorcas, this bovid was first described by the German zoologist Eberhard August Wilhelm von Zimmermann in 1780. Three subspecies are identified. A slender, long-legged antelope, the springbok reaches at the shoulder and weighs between. Both sexes have a pair of black, long horns that curve backwards. The springbok is characterised by a white face, a dark stripe running from the eyes to the mouth, a light brown coat marked by a reddish-brown stripe that runs from the upper foreleg to the buttocks across the flanks like the Thomson's gazelle, and a white rump flap.
Active mainly at dawn and dusk, springbok form harems. In earlier times, springbok of the Kalahari Desert and Karoo migrated in large numbers across the countryside, a practice known as trekbokking. A feature, peculiar but not unique, to the springbok is pronking, in which the springbok performs multiple leaps into the air, up to above the ground, in a stiff-legged posture, with the back bowed and the white flap lifted. Primarily a browser, the springbok feeds on shrubs and succulents; this antelope can live without drinking water for years, meeting its requirements through eating succulent vegetation. Breeding takes place year-round, and peaks in the rainy season, when forage is most abundant. A single calf is born after a five- to six-month-long pregnancy; weaning occurs at nearly six months of age, and the calf leaves its mother a few months later.
Springbok inhabit the dry areas of south and southwestern Africa. The International Union for Conservation of Nature and Natural Resources classifies the springbok as a least concern species. No major threats to the long-term survival of the species are known; the springbok is one of the few antelope species considered to have an expanding population. They are popular game animals and are valued for their meat and skin. The springbok is the national mammal of South Africa.

Etymology

The common name "springbok", first recorded in 1775, comes from the Afrikaans words spring and bok. The scientific name of the springbok is Antidorcas marsupialis. is Greek for "opposite", and for "gazelle" – identifying the animal as not a gazelle. The specific epithet marsupialis comes from the Latin marsupium, and refers to a pocket-like skin flap which extends along the midline of the back from the tail, distinguishing the springbok from true gazelles.

Taxonomy and evolution

The springbok, in the family Bovidae, was first described by the German zoologist Eberhard August Wilhelm von Zimmermann in 1780, who assigned the genus Antilope to the springbok. In 1845, Swedish zoologist Carl Jakob Sundevall placed the springbok as the sole living member of the genus Antidorcas.

Subspecies

Three subspecies of Antidorcas marsupialis are recognised:
Fossil springbok are known from the Pliocene; the antelope appears to have evolved about three million years ago from a gazelle-like ancestor. Three fossil species of Antidorcas have been identified, in addition to the extant form, and appear to have been widespread across Africa. Two of these, A. bondi and A. australis, became extinct around 7,000 years ago. The third species, A. recki, probably gave rise to the extant form A. marsupialis during the Pleistocene, about 100,000 years ago. Fossils have been reported from Pliocene, Pleistocene, and Holocene sites in northern, southern, and eastern Africa. Fossils dating back to 80 and 100 thousand years ago have been excavated at Herolds Bay Cave and Florisbad, respectively.

Adaptations for speed

Convergent shared mutations have been found between the pronghorn and antilopines such as the springbok in genes related to the mitochondrial electron transport chain. Two mutations unique to the Antilopinae and two mutations unique to pronghorns have been found in additional mitochondrial electron transport chain genes. These genes partly explain the speed of these animals.
Springbok have a 58% concentration of glycolytic fast twitch muscle fibres along with an activity of the anaerobic enzyme lactate dehydrogenase four times higher than that of humans in the vastus lateralis muscle, and a high antioxidant capacity. Although their concentration of type IIx fibres and LDH activity are lower than equivalent muscle in wild cheetahs, have an activity of the aerobic enzyme citrate synthase comparable to human endurance runners, and their muscles in general are rich in iron. Females have higher concentrations of type IIx fibres and a higher amount of muscle glycogen than males.

Description

The springbok is a slender antelope with long legs and neck. Both sexes reach at the shoulder with a head-and-body length typically between. The weights for both sexes range between. The tail, long, ends in a short, black tuft. Major differences in the size and weight of the subspecies are seen. A study tabulated average body measurements for the three subspecies. A. m. angolensis males stand tall at the shoulder, while females are tall. The males weigh around, while the females weigh. A. m. hofmeyri is the largest subspecies; males are nearly tall, and the notably shorter females are tall. The males, weighing, are heavier than females, that weigh. However, A. m. marsupialis is the smallest subspecies; males are tall and females tall. Average weight of males is, while for females it is. Another study showed a strong correlation between the availability of winter dietary protein and the body mass.
Dark stripes extend across the white face, from the corner of the eyes to the mouth. A dark patch marks the forehead. In juveniles, the stripes and the patch are light brown. The ears, narrow and pointed, measure. Typically light brown, the springbok has a dark reddish-brown band running horizontally from the upper foreleg to the edge of the buttocks, separating the dark back from the white underbelly. The tail, buttocks, the insides of the legs and the rump are all white. Two other varieties – pure black and pure white forms – are artificially selected in some South African ranches. Though born with a deep black sheen, adult black springbok are two shades of chocolate-brown and develop a white marking on the face as they mature. White springbok, as the name suggests, are predominantly white with a light tan stripe on the flanks.
The three subspecies also differ in their colour. A. m. angolensis has a brown to tawny coat, with thick, dark brown stripes on the face extending two-thirds down to the snout. While the lateral stripe is nearly black, the stripe on the rump is dark brown. The medium brown forehead patch extends to eye level and is separated from the bright white face by a dark brown border. A brown spot is seen on the nose. A. m. hofmeyri is a light fawn, with thin, dark brown face stripes. The stripes on the flanks are dark brown to black, and the posterior stripes are moderately brown. The forehead patch, dark brown or fawn, extends beyond the level of the eyes and mixes with the white of the face without any clear barriers. The nose may have a pale smudge. A. m. marsupialis is a rich chestnut brown, with thin, light face stripes. The stripe near the rump is well-marked, and that on the flanks is deep brown. The forehead is brown, fawn, or white, the patch not extending beyond the eyes and having no sharp boundaries. The nose is white or marked with brown.
The skin along the middle of the dorsal side is folded in, and covered with white hair erected by arrector pili muscles. This white hair is almost fully concealed by the surrounding brown hairs until the fold opens up, and this is a major feature distinguishing this antelope from gazelles. Springbok differ from gazelles in several other ways; for instance, springbok have two premolars on both sides of either jaw, rather than the three observed in gazelles. This gives a total of 28 teeth in the springbok, rather than 32 of gazelles. Other points of difference include a longer, broader, and rigid bridge to the nose and more muscular cheeks in springbok, and differences in the structure of the horns.
Both sexes have black horns, about long, that are straight at the base and then curve backward. In A. m. marsupialis, females have thinner horns than males; the horns of females are only 60 to 70% as long as those of males. Horns have a girth of at the base; this thins to towards the tip. In the other two subspecies, horns of both sexes are nearly similar. The spoor, narrow and sharp, is long.

Ecology and behaviour

Springbok are mainly active around dawn and dusk. Activity is influenced by weather; springbok can feed at night in hot weather, and at midday in colder months. They rest in the shade of trees or bushes, and often bed down in the open when weather is cooler.
The social structure of the springbok is similar to that of Thomson's gazelle. Mixed-sex herds or harems have a roughly 3:1 sex ratio; bachelor individuals are also observed. In the mating season, males generally form herds and wander in search of mates. Females live with their offspring in herds, that very rarely include dominant males. Territorial males round up female herds that enter their territories and keep out the bachelors; mothers and juveniles may gather in nursery herds separate from harem and bachelor herds. After weaning, female juveniles stay with their mothers until the birth of their next calves, while males join bachelor groups.
A study of vigilance behaviour of herds revealed that individuals on the borders of herds tend to be more cautious, and vigilance decreases with group size. Group size and distance from roads and bushes were found to have major influence on vigilance, more among the grazing springbok than among their browsing counterparts. Adults were found to be more vigilant than juveniles, and males more vigilant than females. Springbok passing through bushes tend to be more vulnerable to predator attacks as they cannot be easily alerted, and predators usually conceal themselves in bushes. Another study calculated that the time spent in vigilance by springbok on the edges of herds is roughly double that spent by those in the centre and the open. Springbok were found to be more cautious in the late morning than at dawn or in the afternoon, and more at night than in the daytime. Rates and methods of vigilance were found to vary with the aim of lowering risk from predators.
During the rut, males establish territories, ranging from, which they mark by urinating and depositing large piles of dung. Males in neighbouring territories frequently fight for access to females, which they do by twisting and levering at each other with their horns, interspersed with stabbing attacks. Females roam the territories of different males. Outside of the rut, mixed-sex herds can range from as few as three to as many as 180 individuals, while all-male bachelor herds are of typically no more than 50 individuals. Harem and nursery herds are much smaller, typically including no more than 10 individuals.
In earlier times, when large populations of springbok roamed the Kalahari Desert and Karoo, millions of migrating springbok formed herds hundreds of kilometres long that could take several days to pass a town. These mass treks, known as trekbokking in Afrikaans, took place during long periods of drought. Herds could efficiently retrace their paths to their territories after long migrations. Trekbokking is still observed occasionally in Botswana, though on a much smaller scale than earlier.
Springbok often go into bouts of repeated high leaps of up to into the air – a practice known as pronking or stotting. In pronking, the springbok performs multiple leaps into the air in a stiff-legged posture, with the back bowed and the white flap lifted. When the male shows off his strength to attract a mate, or to ward off predators, he starts off in a stiff-legged trot, leaping into the air with an arched back every few paces and lifting the flap along his back. Lifting the flap causes the long white hairs under the tail to stand up in a conspicuous fan shape, which in turn emits a strong scent of sweat. Although the exact cause of this behaviour is unknown, springbok exhibit this activity when they are nervous or otherwise excited. The most accepted theory for pronking is that it is a method to raise alarm against a potential predator or confuse it, or to get a better view of a concealed predator; it may also be used for display.
Springbok are very fast antelopes, clocked at. They generally tend to be ignored by carnivores unless they are breeding. Cheetahs, lions, leopards, spotted hyenas, African wild dogs, caracals, crocodiles and pythons are major predators of the springbok. Southern African wildcats, black-backed jackals, Verreaux's eagles, martial eagles, and tawny eagles target juveniles. Springbok are generally quiet animals, though they may make occasional low-pitched bellows as a greeting and high-pitched snorts when alarmed.