Gerenuk | |
---|---|
Male | |
Two female gerenuk in the San Diego Zoo | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Family: | Bovidae |
Subfamily: | Antilopinae |
Tribe: | Antilopini |
Genus: | Litocranius Kohl, 1886 |
Species: | L. walleri |
Binomial name | |
Litocranius walleri (Brooke, 1879) | |
distribution of gerenuk (2008) [2] | |
Synonyms [3] | |
|
The gerenuk [lower-alpha 1] (Litocranius walleri), also known as the giraffe gazelle, is a long-necked, medium-sized antelope found in parts of East Africa. The sole member of the genus Litocranius, the gerenuk was first described by the naturalist Victor Brooke in 1879. It is characterised by its long, slender neck and limbs. The antelope is 80–105 centimetres (2 feet 7 inches – 3 feet 5 inches) tall, and weighs between 18 and 52 kilograms (40 and 115 pounds). Two types of colouration are clearly visible on the smooth coat: the reddish brown back or the "saddle", and the lighter flanks, fawn to buff. The horns, present only on males, are lyre-shaped. Curving backward then slightly forward, these measure 25–44 cm (10–17+1⁄2 in).
The gerenuk was first described by Victor Brooke in 1879 on the basis of three male specimens procured on "the mainland of Africa, north of the island of Zanzibar". [4] Brooke used the scientific name Gazella walleri, on the request of Gerald Waller (who provided the specimens) to name it after his deceased brother. [4] The type locality was later corrected by John Kirk, who originally obtained the specimens on the "coast near the River Juba in southern Somalia" before giving them to Waller. [5] In 1886, Franz Friedrich Kohl proposed a new genus for the gerenuk, Litocranius. [6] The common name derives from the Somali name for the animal (gáránúug); the first recorded use of the name dates back to 1895. [7] It is also known as the "giraffe gazelle" due to its similarity to the giraffe. [8]
Two subspecies have been proposed, but these are considered to be independent species by some authors. [3] [9] [10] [11]
In 1997 Colin Groves proposed that Litocranius is a sister taxon of the similarly long-necked dibatag (Ammodorcas clarkei), but withdrew from this in 2000. [3] A 1999 phylogenetic study based on cytochrome b and cytochrome c oxidase subunit III analysis showed that the tribe Antilopini, to which the gerenuk belongs, is monophyletic. [12] In 2013, Eva Verena Bärmann and colleagues (of the University of Cambridge) revised the phylogeny of tribe on the basis of nuclear and mitochondrial gene analysis. The cladogram prepared by them (given below) showed that the springbok (Antidorcas marsupialis) forms a clade with the gerenuk; this clade is sister to the saiga (Saiga tatarica, tribe Saigini) and the genera Antilope (blackbuck), Eudorcas , Gazella and Nanger (of Antilopini). [13]
The gerenuk is a notably tall, slender antelope that resembles gazelles. It is characterised by its long, slender neck and limbs, the flat, wedge-like head and the large, round eyes. Males are nearly 89–105 cm (35–41+1⁄2 in) tall, and the shorter females 80–100 cm (31–39 in); the head-and-body length is typically between 140 and 160 cm (55 and 63 in). Males weigh between 31 and 52 kg (68 and 115 lb); females are lighter, weighing 28–45 kg (62–99 lb). The species is sexually dimorphic. The tail, that ends in a black tuft, measures 25–35 cm (10–14 in). [10] [14]
Two types of colouration are clearly visible on the smooth coat: the reddish brown dorsal parts (the back or the "saddle"), and the lighter flanks, fawn to buff. The underbelly and insides of the legs are cream in colour. The eyes and the mouth are surrounded by white fur. Females have a dark patch on the crown. The horns, present only on males, are lyre-like (S-shaped). Curving backward then slightly forward, these measure 25–44 cm (10–17+1⁄2 in). [14] [10]
The gerenuk resembles the dibatag, with which it is sympatric in eastern and central Somalia and southeastern Ethiopia. Both are brachyodonts and share several facial and cranial features, along with a two-tone colouration of the coat and strong thick horns (only in males). [15] However, there are also some features distinguishing it from the gerenuk, including major morphological differences in horns, horn cores, tail, postorbital area and basioccipital processes. The gerenuk has a longer, heavier neck and a shorter tail. [10] A finer point of difference is the absence of an inward-curving lobe in the lower edge of the ear (near its tip) in the gerenuk. [15] The subspecies of the gerenuk are similar in colouration; the southern gerenuk is the smaller of the two. [10] The Gerenuk stages of growth have a timespan from 4 months to 2.5 years: at four months, their shoulder height is about two-thirds of adult female, at six months their shoulder height is about three-quarters of adult female, at eight months their horn tips are clearly visible (about 1cm long), at one year their shoulder height is nearly equal to adult female but body more lightly built, their horns are slightly less than half ear-length, then curve, at two years their horns are about 1.5 times their ear length and the second curve becomes noticeable with the tips turning forwards, and finally at two and a half years the double curve in the horns are nearly completed. [16]
The gerenuk is a diurnal animal (active mainly during the day), though it typically stands or rests in shade during the noon. Foraging and feeding is the major activity throughout the day; females appear to spend longer time in feeding. The gerenuk may expose itself to rain, probably to cool its body. [17] The social structure consists of small herds of two to six members. Herds typically comprise members of a single sex, though female herds additionally have juveniles. Some males lead a solitary life. [10]
Fighting and travel are uncommon, possibly as a strategy to save energy for foraging. [8] Both sexes maintain home ranges 3–6 km2 (1–2+1⁄2 sq mi) large, and might overlap. Those of males are scent-marked with preorbital gland secretions and guarded - hence these may be termed territories. The sedentary tendency of the antelope appears to increase with age. [11]
Primarily a browser, the gerenuk feed on foliage of bushes as well as trees, shoots, herbs, flowers and fruits. [18] It can reach higher branches and twigs better than other gazelles and antelopes by standing erect on its hindlegs and elongating its neck; this helps it reach over 2 m (6 ft 7 in) above the ground. [11] Acacia species are eaten whenever available, [11] while evergreen vegetation forms the diet during droughts. [14] The pointed mouth assists in extracting leaves from thorny vegetation. [11] The gerenuk does not drink water regularly. [18] Major predators of the antelope include African wild dogs, cheetahs, hyenas, lions and leopards. [10]
Gerenuk reproduce throughout the year. Females reach sexual maturity at around one year, and males reach sexual maturity at 1.5 years, although in the wild they may only be successful after acquiring a territory (perhaps 3.5 years). [18] The gestation period is about seven months. They are born one at a time, weighing about 3 kg (7 lb) at birth. Offspring were produced through artificial insemination for the first time in 2010 at White Oak Conservation in Yulee, Florida. Four female calves were born, and one of the four was later inseminated successfully by White Oak and SEZARC (South-East Zoo Alliance for Reproduction & Conservation), creating a second generation of calves born from artificial insemination. [19] Gerenuk can live thirteen years or more in captivity, and at least eight years in the wild. [18]
The springbok or springbuck is an antelope found mainly in south and southwest Africa. The sole 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 71 to 86 cm at the shoulder and weighs between 27 and 42 kg. Both sexes have a pair of black, 35-to-50 cm (14-to-20 in) 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.
The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Eastern Europe. Antelopes do not form a monophyletic group, as some antelopes are more closely related to other bovid groups, like bovines, goats, and sheep, than to other antelopes.
The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, sheep and goats. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, the family Bovidae consists of 11 major subfamilies and thirteen major tribes. The family evolved 20 million years ago, in the early Miocene.
The klipspringer is a small antelope found in eastern and southern Africa. The sole member of its genus and subfamily/tribe, the klipspringer was first described by German zoologist Eberhard August Wilhelm von Zimmermann in 1783. The klipspringer is a small, sturdy antelope; it reaches 43–60 centimetres at the shoulder and weighs from 8 to 18 kilograms. The coat of the klipspringer, yellowish gray to reddish brown, acts as an efficient camouflage in its rocky habitat. Unlike most other antelopes, the klipspringer has a thick and coarse coat with hollow, brittle hairs. The horns, short and spiky, typically measure 7.5–9 cm.
The lesser kudu is a medium-sized bushland antelope found in East Africa. The species is a part of the ungulate genus Tragelaphus, along with several other related species of striped, spiral-horned African bovids, including the related greater kudu, the bongo, bushbuck, common and giant elands, nyala and sitatunga. It was first scientifically described by English zoologist Edward Blyth (1869).
The hirola, also called the Hunter's hartebeest or Hunter's antelope, is a critically endangered antelope species found as of now, only in Kenya along the border of Somalia. It was first described by the big game hunter and zoologist H.C.V. Hunter in 1888. It is the only living member of the genus Beatragus, though other species are known from the fossil record. The global hirola population is estimated at 300–500 animals and there are none in captivity. According to a document produced by the International Union for Conservation of Nature "the loss of the hirola would be the first extinction of a mammalian genus on mainland Africa in modern human history".
The royal antelope is a West African antelope recognized as the world's smallest. It was first described by Swedish zoologist Carl Linnaeus in 1758. It stands up to merely 25 cm (10 in) at the shoulder and weighs 2.5–3 kg (5.5–6.6 lb). A characteristic feature is the long and slender legs, with the hindlegs twice as long as the forelegs. Horns are possessed only by males; the short, smooth, spiky horns measure 2.5–3 cm (0.98–1.18 in) and bend backward. The soft coat is reddish to golden brown, in sharp contrast with the white ventral parts. In comparison to Bates's pygmy antelope, the royal antelope has a longer muzzle, broader lips, a smaller mouth and smaller cheek muscles.
The antilopines are even-toed ungulates belonging to the subfamily Antilopinae of the family Bovidae. The members of tribe Antilopini are often referred to as true antelopes, and include the gazelles, blackbucks, springboks, gerenuks, dibatags, and Central Asian gazelles. True antelopes occur in much of Africa and Asia, with the highest concentration of species occurring in East Africa in Sudan, Eritrea, Ethiopia, Somalia, Kenya, and Tanzania. The saiga inhabits Central and Western Asia, mostly in regions from the Tibetan Plateau and north of the Indian Subcontinent. The dwarf antelope species of tribe Neotragini live entirely in sub-Saharan Africa.
The rhim gazelle or rhim, also known as the slender-horned gazelle, African sand gazelle or Loder's gazelle, is a pale-coated gazelle with long slender horns and well adapted to desert life. It is considered an endangered species because fewer than 2500 are left in the wild. They are found in Algeria, Egypt, Tunisia and Libya, and possibly Chad, Mali, Niger, and Sudan.
Thomson's gazelle is one of the best known species of gazelles. It is named after explorer Joseph Thomson and is sometimes referred to as a "tommie". It is considered by some to be a subspecies of the red-fronted gazelle and was formerly considered a member of the genus Gazella within the subgenus Eudorcas, before Eudorcas was elevated to genus status.
Antidorcas is a genus of antelope that includes the living springbok and several fossil species.
The oribi is a small antelope found in eastern, southern and western Africa. The sole member of its genus, it was described by the German zoologist Eberhard August Wilhelm von Zimmermann in 1783. While this is the only member in the genus Ourebia, eight subspecies are identified. The oribi reaches nearly 50–67 centimetres (20–26 in) at the shoulder and weighs 12–22 kilograms (26–49 lb). It possesses a slightly raised back, and long neck and limbs. The glossy, yellowish to rufous brown coat contrasts with the white chin, throat, underparts and rump. Only males possess horns; the thin, straight horns, 8–18 centimetres (3.1–7.1 in) long, are smooth at the tips and ringed at the base.
The dibatag, or Clarke's gazelle, is a medium-sized slender antelope native to Ethiopia and Somalia. Though not a true gazelle, it is similarly marked, with long legs and neck. It is often confused with the gerenuk due to their striking resemblance. The typical head-and-body length is about 103 to 117 cm. They stand up to about 80 to 90 cm. Male dibatag weigh between 20 and 35 kg, whereas females range from 22 and 29 kg. The length of the curved horns, present only on males, is typically between 10 and 25 cm. The upper parts are gray to fawn, while the dorsal and lateral areas are cinnamon to rufous. The underparts, rump and the insides of the legs are all white. While markings are visible on the face, there are none on the flanks or the buttocks.
The mountain reedbuck is an antelope found in mountainous areas of much of sub-Saharan Africa.
The red-fronted gazelle is widely but unevenly distributed gazelle across the middle of Africa from Senegal to northeastern Ethiopia. It is mainly resident in the Sahel zone, a narrow cross-Africa band south of the Sahara, where it prefers arid grasslands, wooded savannas and shrubby steppes.
Damaliscus lunatus is a large African antelope of the genus Damaliscus and subfamily Alcelaphinae in the family Bovidae, with a number of recognised geographic subspecies. Some authorities have split the different populations of the species into different species, although this is seen as controversial. Common names include topi, sassaby, tiang and tsessebe.
Salt's dik-dik is a small antelope found in semidesert, bushland, and thickets in the Horn of Africa, but marginally also in northern Kenya and eastern Sudan. It is named after Henry Salt, who was the first European to acknowledge the species in Abyssinia in the early 19th century.
The Grand Bara, Bara Wein or Bada Wein, is a desert in southern Djibouti. It consists of large areas of sand flats, with sparse, semi-desert and desert grasses and scrub vegetation. A road built in 1981 passes through the area, connecting the capital Djibouti City with the south. Prior to the arrival of the French, the extremely arid interior was inhabited primarily by the Issa Somali. Runners make their way across the Grand Bara Desert during the Annual Grand Bara 15K race.
Antilopini is a tribe of bovids often referred as true antelopes like gazelles. They live in and around the Sahara, Horn of Africa, throughout eastern and southern Africa, and Eurasia. Depending on species, the females have either very short and/or thin horns compared with the males, or no horns at all. They have smooth and glossy tan and white coats. Most species have black stripes and facial markings. They have a territorial male as a leader in herds and sometimes group with other species, such as Grant's gazelle joining with Thomson's gazelle. They can reach top speeds of 50 miles per hour (80 km/h) and have the ability to jump and turn sharply. They have adapted well to running in open environments.
Eritrean gazelle is a species of gazelle found east of the Nile River in Eritrea, Ethiopia and Sudan. It was considered a subspecies of the red-fronted gazelle or conspecific with Thomson's gazelle and Mongalla gazelle by some authors in the past. This small gazelle stands nearly 67 cm (26 in) at the shoulder and weighs between 15 and 35 kg. The coat is dark reddish brown with a dark reddish stripe on the flanks, except for the underparts and the rump which are white. Horns, present in both sexes, measure 15 to 35 cm in length.