Gerenuk

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Gerenuk
San Diego Zoo Avril 2013 05.JPG
Male
San Diego Zoo Avril 2013 13.JPG
Two female gerenuk in the San Diego Zoo
Scientific classification Red Pencil Icon.png
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)
Gerenuk Litocranius walleri distribution map.png
Distribution of gerenuk (2008) [1]
Synonyms [2]
  • Gazella walleri(Brooke, 1879)
  • Lithocranius walleri Thomas, 1891

The gerenuk ( /ˈɡɛrɪnʊk,ɡəˈrɛnək/ ; Somali : garanuug; Litocranius walleri), also known as the giraffe gazelle, is a long-necked antelope found in the Horn of Africa and the drier 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 28 and 52 kilograms (62 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+12 in).

Contents

Taxonomy and phylogeny

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". [3] Brooke used the scientific name Gazella walleri, on the request of Gerald Waller (who provided the specimens) to name it after his deceased brother. [3] The type locality was later corrected by John Kirk, who originally obtained the specimens on the "coast near the River Juba in southern Somaliland" before giving them to Waller. [4] In 1886, Franz Friedrich Kohl proposed a new genus for the gerenuk, Litocranius. [5] The common name derives from the Somali name for the animal (gáránúug); the first recorded use of the name dates back to 1895. [6] It is also known as the "giraffe gazelle" due to its similarity to the giraffe. [7]

Two subspecies have been proposed, but these are considered to be independent species by some authors. [2] [8] [9] [10]

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. [2] 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. [11] 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). [12]

Gazella

Blackbuck (Antilope cervicapra) Antilope cervicapra from velavadar.JPG

Eudorcas

Nanger

Gerenuk (Litocranius walleri)

Springbok (Antidorcas marsupialis) Antidorcas marsupialis, male (Etosha, 2012).jpg

Saiga (Saiga tatarica) Saiga antelope at the Stepnoi Sanctuary (cropped).jpg

Oribi (Ourebia ourebi) Sudan Oribi (Ourebia montana) male (18172324646).jpg

Description

Close-up view of a male. Note the white facial markings and the lyre-shaped horns. Gerenuk (3847435602).jpg
Close-up view of a male. Note the white facial markings and the lyre-shaped horns.

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+12 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). [9] [13]

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+12 in). [13] [9]

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). [14] 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. [9] 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. [14] The subspecies of the gerenuk are similar in colouration; the southern gerenuk is the smaller of the two. [9]

Ecology and behaviour

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. [15] 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. [9]

Fighting and travel are uncommon, possibly as a strategy to save energy for foraging. [7] Both sexes maintain home ranges 3–6 km2 (1–2+12 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. [10]

Diet

Gerenuks feeding Gerenuks in Samburu.jpg
Gerenuks feeding

Primarily a browser, the gerenuk feed on foliage of bushes as well as trees, shoots, herbs, flowers and fruits. [16] 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. [10] Acacia species are eaten whenever available, [10] while evergreen vegetation forms the diet during droughts. [13] The pointed mouth assists in extracting leaves from thorny vegetation. [10] The gerenuk does not drink water regularly. [16] Major predators of the antelope include African wild dogs, cheetahs, hyenas, lions and leopards. [9]

Reproduction

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). [16] 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. [17] Gerenuk can live thirteen years or more in captivity, and at least eight years in the wild. [16]

Related Research Articles

Springbok Antelope of southern and southwestern Africa

The springbok is a medium-sized antelope found mainly in southern and southwestern 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 fore leg to the buttocks across the flanks like the Thomson's gazelle, and a white rump flap.

Antelope Term referring to an even-toed ruminant

The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia.

Bovidae Family of mammals belonging to even-toed ungulates

The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes nilgai, bison, African buffalo, water buffalo, antelopes, wildebeest, hartebeest, Common tsessebe, bontebok, hirola, sheep, goats, muskoxen, and domestic cattle. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, the family Bovidae consists of eight major subfamilies apart from the disputed Peleinae and Pantholopinae. The family evolved 20 million years ago, in the early Miocene.

Klipspringer Species of mammal

The klipspringer is a small antelope found in eastern and southern Africa. The sole member of its genus, 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.

Sitatunga Species of swamp-dwelling antelope

The sitatunga or marshbuck is a swamp-dwelling antelope found throughout central Africa, centering on the Democratic Republic of the Congo, the Republic of the Congo, Cameroon, parts of Southern Sudan, Equatorial Guinea, Burundi, Ghana, Botswana, Rwanda, Zambia, Gabon, the Central African Republic, Tanzania, Uganda and Kenya. The sitatunga is confined to swampy and marshy habitats. Here they occur in tall and dense vegetation as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps.

Lesser kudu Species of antelope

The lesser kudu is a forest antelope found in East Africa. It is placed in the genus Tragelaphus and family Bovidae. It was first scientifically described by the English zoologist Edward Blyth in 1869. The head-and-body length is typically 110–140 cm (43–55 in). Males reach about 95–105 cm (37–41 in) at the shoulder, while females reach 90–100 cm (35–39 in). Males typically weigh 92–108 kg (203–238 lb) and females 56–70 kg (123–154 lb). The females and juveniles have a reddish-brown coat, while the males become yellowish grey or darker after the age of 2 years. Horns are present only on males. The spiral horns are 50–70 cm (20–28 in) long, and have two to two-and-a-half twists.

Roan antelope Species of mammal

The roan antelope is a savanna antelope found in western, central, and southern Africa.

Hirola Species of antelope

The hirola, Hunter's hartebeest or Hunter's antelope, is a critically endangered antelope species found on the border between Kenya and Somalia. They were discovered by the big game hunter and zoologist H.C.V. Hunter in 1888, although the African peoples of the region knew of its existence even before this "discovery". 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".

Common tsessebe

The topi, sassaby, tiang or tsessebe 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.

Royal antelope Species of mammal

The royal antelope is a West African antelope, recognized as the world's smallest antelope. It was first described by Swedish zoologist Carl Linnaeus in 1758. It stands up to merely 25 centimetres (10 in) at the shoulder and weighs 2.5–3 kilograms (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 centimetres (1.0–1.2 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.

Blackbuck Antelope native to India and Nepal

The blackbuck, also known as the Indian antelope, is an antelope native to India and Nepal. It inhabits grassy plains and lightly forested areas with perennial water sources. It stands up to 74 to 84 cm high at the shoulder. Males weigh 20–57 kg (44–126 lb), with an average of 38 kg (84 lb). Females are lighter, weighing 20–33 kg (44–73 lb) or 27 kg (60 lb) on average. Males have 35–75 cm (14–30 in) long, ringed horns, though females may develop horns as well. The white fur on the chin and around the eyes is in sharp contrast with the black stripes on the face. The coats of males show a two-tone colouration; while the upper parts and outsides of the legs are dark brown to black, the underparts and the insides of the legs are white. Females and juveniles are yellowish fawn to tan. The blackbuck is the sole living member of the genus Antilope and was scientifically described by Carl Linnaeus in 1758. Two subspecies are recognized.

Antilopinae Subfamily of mammals

The Antilopinae are a subfamily of Bovidae. The gazelles, blackbucks, springboks, gerenuks, dibatags, and Central Asian gazelles are often referred to as "true antelopes", and are usually classified as the only representatives of the Antilopinae. 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 saigas and Tibetan antelopes are related to true antelopes (Antilopinae) and goats (Caprinae), but often placed in their own subfamily, Saiginae. These animals inhabit much of central and western Asia. The dwarf antelopes are sometimes placed in a separate subfamily, Neotraginae, and live entirely in sub-Saharan Africa. The antilopinae are a subfamily of bovidaes that roam the East African savannas, they have acclimated to possess wider insertion muscles to enable them to avoid predators in the open savanna.

Rhim gazelle Species of mammal

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, and Libya, and possibly Chad, Mali, Niger, and Sudan.

Thomsons gazelle Species of gazelle

Thomson's gazelle is one of the best-known 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. Thomson's gazelles can be found in numbers exceeding 200,000 in Africa and are recognized as the most common type of gazelle in East Africa. The Thomson's gazelle can reach speeds of 80–90 km/h (50–55 mph). It is the fourth-fastest land animal, after the cheetah, pronghorn, and springbok.

Oribi Species of mammal

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. 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.

Dibatag Genus of mammals

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.

Zebra duiker Species of mammal

The zebra duiker is a small antelope found primarily in Liberia, as well as the Ivory Coast, Sierra Leone, and occasionally Guinea. They are sometimes referred to as the banded duiker or striped-back duiker. It is believed to be one of the earliest duiker species to have evolved.

Red-fronted gazelle Species of mammal

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.

Antilopini Tribe of mammals

Antilopini is a tribe of medium-sized gazelles and dwarf antelopes that 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.

Heuglins gazelle Species of mammal

Heuglin's gazelle, also known as the 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.

References

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