Antelope

Antelope are ruminant hoofed mammals of the family Bovidae in the order of even-toed ungulates. These animals are spread relatively evenly throughout the various subfamilies of Bovidae and many are more closely related to cows or goats than to each other. There are many species of antelope, ranging in size from the tiny Royal Antelope to the ox-like Elands.

Male antelope are noted for their horns, which are permanent, unlike the annually-shed antlers of deer, and which often take on extravagant curved shapes such as arcs and helices. The midrange antelope, such as gazelles, impala, and blackbuck antelope, typically have a light and elegant frame, slender, graceful limbs, small cloven hoofs, and a short tail. Small antelope and large antelope can both be quite variable in form, but tend to have proportionally shorter legs and thicker builds than the mid-sized antelope.

Antelope exhibit different defensive behaviors based on their size, habitat, and number. Small solitary antelope tend to live in dense forested areas, and defend themselves by hiding. Duikers get their name from this ability to dive into the vegetation. Gazelle-sized antelope run and leap, and some species exhibit the unique behaviour of pronking or stotting. Large antelope congregate in larger herds and can depend on running or group defense.

Antelope are found in a wide range of habitats, typically woodland, forest, savannahs, grassland plains, and marshes. Several species are adapted to mountains and rocky outcrops, a few to deserts (both hot and cold), and a couple are semi-aquatic and live in swamps.

Species and Distribution

Antelopes occur naturally in Eurasia and Africa. There are about 90 species, most of which are native to Africa, where the largest herds are also to be found, in about 30 genera. About 15 species are endangered.

Antelope are typically divided into "tribes", or subfamilies under the family Bovidae.

Blackbuck antelope and Gemsbok have been imported into the United States, primarily for the purpose of "exotic game hunts", common in Texas. While blackbuck antelope and other species have established wild populations in parts of Texas, they are not native to the United States.

There are no true antelope native to the Americas. The Pronghorn "Antelope" of the Great Plains belongs to family Antilocapridae, not Bovidae. They can be distinguished by the horns, which are branched and shed. True antelope have horns which are unbranched and are never shed.

Most familiar species of antelope are located in Africa, but some exist in Asia as well. The Arabian peninsula is home to the Arabian Oryx and Dorcas gazelle, while India and Southeast Asia have the Four-horned Antelope, Tibetan antelope, Saiga antelope, Nilgai, Chinkara, and Blackbuck.

Antelope are not a cladistic or taxonomically defined group. The term is used loosely to describe all members of the family Bovidae which do not fall under the category of sheep, cattle, or goat. Usually all species of the Alcelaphinae, Antilopinae, Hippotraginae, Reduncinae, Cephalophinae, many Bovinae and the Impala are called antelopes.

Classification

There are at least two classification systems at the subfamily level of the Bovidae. In the "lumped" system (of, e.g., Kingdon 1997), antelope occur in both subfamilies—the Bovinae (alongside the cattle) and the Antilopinae (alongside the sheep and goats). The alternative classification of 10 subfamilies is given under " Bovid" in this encyclopaedia—in this classification, antelope occur in 9 of the 10 subfamilies (one of which is the single-species subfamily of the Tibetan Antelope).

Antelope are not a monophyletic group, but a miscellaneous category for members of the family Bovidae that are not cattle, sheep, goats, or bison. Confusingly, Pronghorn (commonly known as Pronghorn Antelope) are not antelope, but belong to their own family, Antilocapridae.

Physical characteristics

The characteristics of bovids in general are: long legs; even number of hoofed toes (as per all even-toed ungulates); in most species the males are horned, and in some species the females are also; most have horizontally oriented pupils; they ruminate. In all species, the males display horns (typically two, but sometimes four). Horns are not shed and are not made of bone, which distinguishes them from antlers.

These basic characteristics, however, mask huge differences in appearance between antelopes, cattle, goats and sheep, and among the antelopes themselves. For example, a male Common Eland can measure 178 cm at the shoulder and weigh almost 950 kg, whereas an adult Royal Antelope may stand only 24 cm at the shoulder and weigh a mere 1.5 kg.

Not surprisingly for animals with long slender yet powerful legs, many antelopes have long strides and can run fast. Some (e.g. Klipspringer) are also adapted to climbing in rock kopjes. Both Dibatags and Gerenuks habitually stand on their two hind legs to reach acacia and other tree foliage. Different antelope have different body types which can affect movement. Duikers are short, bush dwelling antelope that can pick through dense foliage and dive into the shadows rapidly. Gazelles and Springbok are known for their speed and leaping abilities. Even larger antelope, such as Nilgai, Elands, and Kudus, are capable of jumping 8 feet or greater, although their running speed is restricted by their greater mass.

Antelopes have a wide variety of coverings, through most have a dense coat of short fur. In most species, the coat (pelage) is some variation of a brown colour (or several shades of brown); often with white or pale under-bodies. Exceptions include the zebra-marked Zebra Duiker, the grey, black and white Jentink's Duiker and the Black Lechwe. Most of the "spiral-horned" antelopes have pale vertical stripes on their backs. Many desert and sub-desert species are particularly pale, some almost silvery or whitish (e.g. Arabian Oryx); the Beisa and Southern Oryxes have gray and black pelage with vivid black-and-white faces. Common features of various gazelles are a white rump, which flashes a warning to others when they run from danger, and a dark stripe mid-body (the latter feature is also shared by the Springbok and Beira). The Springbok also has a pouch of white brushlike hairs running along its back, which opens up when the animal senses danger, causing the dorsal hairs to stand on end.

Antelopes are ruminants, and thus have well-developed molar teeth, which grind cud (food balls stored in the stomach) into a pulp for further digestion. They have no upper incisors, but rather a hard upper gum pad, against which their lower incisors bite to tear grass stems and leaves.

Like many other herbivores, antelopes rely on keen senses to avoid predators. Their eyes are placed on the sides of their heads, giving them a broad radius of vision with minimal binocular vision. The fact that most species have their pupils elongated horizontally also helps in this respect. Acute senses of smell and hearing, give antelope the ability to perceive danger at night out in the open (when predators are often on the prowl). These same senses play an important role in contact between individuals of the same species: markings on head, ears, legs and rumps are used in such communication—many species "flash" such markings, as well as their tails; vocal communications include loud barks, whistles, "moos" and trumpeting; many species also use scent marking to define their territories or simply to maintain contact with their relatives and neighbours.

Many antelope are sexually dimorphic. In most species, both sexes have horns, but those of males tend to be larger. There is a tendency for males to be larger than the females; however, exceptions in which the females tend to be heavier than the males include the Bush Duiker, Dwarf Antelope, Cape Grysbok and Oribi, all rather small species. A number of species have hornless females (e.g. Sitatunga, Red Lechwe, and Suni). In some species, the males and females have different coloured pelage (e.g. Blackbuck and Nyala).

Size and shape of horns varies immensely. Those of the duikers and dwarf antelopes tend to be simple "spikes", but differ in the angle to the head from backward curved and backward pointing (e.g. Yellow-backed Duiker) to straight and upright (e.g. Steenbok). Other groups have twisted (e.g. Common Eland), spiral (e.g. Greater Kudu), "recurved" (e.g. the reedbucks), lyrate (e.g. Impala), or long, curved (e.g. the oryxes) horns. Horns are efficient weapons and tend to be better developed in those species where males genuinely fight over females—horns are clashed in combat. It is much more common for males to use their horns against each other than against another species. The boss of the horns is typically arranged in such a way that two antelope striking at each other's horns cannot crack each other's skulls, making a fight via horn more ritualized than dangerous. Many species have ridges in their horns for at least 2/3 the length of their horns.

It is difficult to determine how long antelope live in the wild. With the preferance of predators towards old and infirm individuals who can no longer sustain peak speeds, few wild prey-animals live as long as their biological potential. In captivity, wildebeest have lived beyond 20 years old, and Impalas have reached their late teens. In the wild, few individuals of prey species live to old age, as the old and weak fall easier prey to their predators; antelopes are no exception to this rule.

Behaviour

With food that does not move, antelopes (like other herbivores) do not need any great intelligence. However, they do need to be able to react quickly in the presence of a predator—thus, they tend to be fast runners. They are agile (able to execute fast turns on the run) and have good endurance (ability to keep running for some time)—these are advantages when pursued by sprint-dependent predators like cheetah, which are the fastest of land animals, but tire quickly.

Different species differ in their behaviour in the presence of predators, and these differences are often associated with habitat. For example, the Steenbok of open woodland will lie low until the last minute and then bound away. Plains-living species, such as gazelles, do not have this choice and must flee at speed when a predator approaches. Reaction distances vary with predator species and predator behaviour. For example, gazelles may not flee from a lion until it is closer than 200 m (650 ft)—lions hunt as a pride or by surprise, usually by stalking, one that can be seen clearly is unlikely to attack. However, sprint-dependent cheetahs will cause gazelles to flee at a range of over 800 m (0.5 mile).

Species of forest, woodland or bush tend to be sedentary, but many of the plains species undertake huge migrations. These migrations enable grass-eating species to follow the rains and therefore their food supply. The gnus and gazelles of East Africa perform some of the most impressive mass migratory circuits of all mammals.

Hybrid Antelope

A wide variety of antelope hybrids have been recorded in zoos, game parks, and wildlife ranches. This is due to either a lack of more appropriate mates in enclosures shared with other species or a misidentification of species. The ease of hybridization shows how closely related some antelope species are. It is probable that some so-called species are actually variant populations of the same species and are prevented from hybridization in the wild by behavioural or geographical differences.

Most hybrids occur between species within the same genus. All reported examples occur within the same sub-family. As with most mammal hybrids, the less closely related the parents, the more likely that the offspring will be sterile.

Cultural aspects

The antelope's horn is prized for medicinal and magical powers in many places. The horn of the male saiga in Eastern practice is ground as an aphrodisiac, for which it has been hunted nearly to extinction. In the Congo, it is thought to confine spirits. Christian iconography sometimes uses the antelope's two horns as a symbol of the two spiritual weapons that Christians possess: the Old Testament and the New Testament. Their ability to run swiftly has also led to their association with the wind, such as in the Rig Veda, as the steeds of the Maruts and the wind god Vayu.