Waterbuck | |
---|---|
Male K. e. defassa Queen Elizabeth National Park, Uganda | |
Female K. e. ellipsiprymnus Chobe National Park, Botswana | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Family: | Bovidae |
Genus: | Kobus |
Species: | K. ellipsiprymnus |
Binomial name | |
Kobus ellipsiprymnus (Ogilby, 1833) | |
Subspecies | |
See text | |
Distribution of subspecies of waterbuck |
The waterbuck (Kobus ellipsiprymnus) is a large antelope found widely in sub-Saharan Africa. It is placed in the genus Kobus of the family Bovidae. It was first described by Irish naturalist William Ogilby in 1833. Its 13 subspecies are grouped under two varieties: the common or ellipsiprymnus waterbuck and the defassa waterbuck. The head-and-body length is typically between 177 and 235 cm (70 and 93 in) and the typical height is between 120 and 136 cm (47 and 54 in). In this sexually dimorphic antelope, males are taller and heavier than females. Males reach roughly 127 cm (50 in) at the shoulder, while females reach 119 cm (47 in). Males typically weigh 198–262 kg (437–578 lb) and females 161–214 kg (355–472 lb). Their coat colour varies from brown to grey. The long, spiral horns, present only on males, curve backward, then forward, and are 55–99 cm (22–39 in) long.
Waterbucks are rather sedentary in nature. [2] As gregarious animals, they may form herds consisting of six to 30 individuals. These groups are either nursery herds with females and their offspring or bachelor herds. Males start showing territorial behaviour from the age of 5 years, but are most dominant from the six to nine. The waterbuck cannot tolerate dehydration in hot weather, and thus inhabits areas close to sources of water. Predominantly a grazer, the waterbuck is mostly found on grassland. In equatorial regions, breeding takes place throughout the year, but births are at their peak in the rainy season. The gestational period lasts 7–8 months, followed by the birth of a single calf.
Waterbucks inhabit scrub and savanna areas along rivers, lakes, and valleys. Due to their requirement for grasslands and water, waterbucks have a sparse ecotone distribution. The IUCN lists the waterbuck as being of least concern. More specifically, the common waterbuck is listed as of least concern. while the defassa waterbuck is near threatened. The population trend for both is downwards, especially that of the defassa, with large populations being eliminated from certain habitats because of poaching and human disturbance.
The scientific name of the waterbuck is Kobus ellipsiprymnus. The waterbuck is one of the six species of the genus Kobus in the family Bovidae. It was first described by Irish naturalist William Ogilby in 1833. The generic name Kobus is a Neo-Latin word, originating from an African name, koba. The specific name ellipsiprymnus refers to the white, elliptical ring on the rump, [3] from the Greek ellipes (ellipse) and prymnos (prumnos, hind part). [4] The animal acquired the vernacular name "waterbuck" due to its heavy dependence on water as compared to other antelopes and its ability to enter into water for defence. [5]
The type specimen of the waterbuck was collected by South African hunter-explorer Andrew Steedman in 1832. This specimen was named Antilope ellipsiprymnus by Ogilby in 1833. This species was transferred to the genus Kobus in 1840, becoming K. ellipsiprymnus. It is usually known as the common waterbuck. In 1835, German naturalist Eduard Rüppell collected another specimen, which differed from Steedman's specimen in having a prominent white ring on its rump. Considering it a separate species, Rüppell gave it the Amharic name "defassa" waterbuck and scientific name Antilope defassa. [3] Modern taxonomists, however, consider the common waterbuck and the defassa waterbuck a single species, K. ellipsiprymnus, given the large number of instances of hybridisation between the two. [3] Interbreeding between the two takes place in the Nairobi National Park owing to extensive overlapping of habitats. [6] Though both groups occur in Zambia as well, their ranges are separated by relief features or by the Muchinga escarpment. [7]
Not many fossils of the waterbuck have been found. Fossils were scarce in the Cradle of Humankind, occurring only in a few pockets of the Swartkrans. [8] On the basis of Valerius Geist's theories about the relation of social evolution and dispersal in ungulates during the Pleistocene, [9] the ancestral home of the waterbuck is considered to be the eastern coast of Africa, with the Horn of Africa to the north and the East African Rift Valley to the west. [3]
On the basis of coat colour, 37 subspecies of the waterbucks had been initially recognised. They were classified into two groups: the ellipsiprymnus waterbuck group and the defassa waterbuck group. Owing to the large number of variations in the coat colour in the defassa waterbuck group, as many as 29 subspecies were included in it; the ellipsiprymnus waterbuck group consisted of eight subspecies. In 1971, however, the number of subspecies was reduced to 13 (4 for the ellipsenprymnus waterbuck group and 9 for the defassa waterbuck group). The subspecies are listed below, along with notes about the former subspecies which were recombined into a single subspecies: [3] [10]
The waterbuck is the largest amongst the six species of Kobus. [3] It is a sexually dimorphic antelope, with the males nearly 7% taller than females and around 8% longer. [3] The head-and-body length is typically 177–235 cm (70–93 in) and the typical height is 120–136 cm (47–54 in). [11] Males reach approximately 127 cm (50 in) at the shoulder, while females reach 119 cm (47 in). The waterbuck is one of the heaviest antelopes. A newborn typically weighs 13.6 kg (30 lb), and growth in weight is faster in males than in females. [3] Males typically weigh 198–262 kg (437–578 lb) and females 161–214 kg (355–472 lb). [12] The tail is 22–45 cm (8.7–17.7 in) long. [4]
The waterbuck has a robust build. The shaggy coat is reddish brown to grey, and becomes progressively darker with age. Males are darker than females. [13] Though apparently thick, the hair is sparse on the coat. The hair on the neck is, however, long and shaggy. When sexually excited, the skin of the waterbuck secretes a greasy substance with the odour of musk, giving it the name "greasy kob". [3] [12] The odor of this is so unpleasant that it repels predators. [14] This secretion also assists in water-proofing the body when the animal dives into water. [13] The facial features include a white muzzle and light eyebrows and lighter insides of the ears. A cream-coloured patch (called "bib") is on the throat. Waterbuck are characterised by a long neck and short, strong, black legs. [4] [11] Females have two nipples. [7] Preorbital glands, foot glands, and inguinal glands are absent. [15]
The common waterbuck and the defassa waterbuck are remarkably different in their physical appearances. Measurements indicate greater tail length in the latter, whereas the common waterbuck stands taller than the defassa waterbuck. [16] However, the principal differentiation between the two types is the white ring of hair surrounding the tail on the rump, which is a hollow circle in the common waterbuck, but covered with white hair in the defassa waterbuck. [12]
The long, spiral horns curve backward, then forward. Found only on males, the horns range from 55 to 99 cm (22 to 39 in) in length. [12] To some extent, the length of the horns is related to the bull's age. A rudimentary horn in the form of a bone lump may be found on the skulls of females. [13]
Waterbuck are rather sedentary in nature, though some migration may occur with the onset of monsoon. A gregarious animal, the waterbuck may form herds consisting of six to 30 individuals. The various groups are the nursery herds, bachelor herds and territorial males. Herd size increases in summer, whereas groups fragment in the winter months, probably under the influence of food availability. [17] As soon as young males start developing horns (at around seven to nine months of age), they are chased out of the herd by territorial bulls. These males then form bachelor herds and may roam in female home ranges. [4] Females have home ranges stretching over 200–600 hectares (0.77–2.32 sq mi ; 490–1,480 acres ). A few females may form spinster herds. [18] Though females are seldom aggressive, minor tension may arise in herds. [16]
Males start showing territorial behaviour from the age of 5 years, but are most dominant from 6 to 9 years. Territorial males hold territories 4–146 hectares (0.015–0.564 sq mi ; 9.9–360.8 acres ) in size. Males are inclined to remain settled in their territories, though over time they may leave inferior territories for more spacious ones. Marking of territories includes no elaborate rituals; dung and urine are occasionally dropped. [18] After the age of ten years, males lose their territorial nature and are replaced by a younger bull, following which they recede to a small and unprotected area. [16] There is another social group, that of the satellite males, which are mature bulls as yet without their own territories, who exploit resources, particularly mating opportunities, even in the presence of the dominant bull. The territorial male may allow a few satellite males into his territory, and they may contribute to its defence. However, gradually they may deprive the actual owner of his territory and seize the area for themselves. In a study in the Lake Nakuru National Park, only 7 percent of the adult males held territories, and only half of the territorial males tolerated one or more satellite males. [19] [20]
Territorial males may use several kinds of display. In one type of display, the white patch on the throat and between the eyes is clearly revealed, and other displays can demonstrate the thickness of the neck. These activities frighten trespassers. Lowering of the head and the body depict submission before the territorial male, who stands erect. [7] Fights, which may last up to thirty minutes, involve threat displays typical of bovids accompanied by snorting. [18] Fights may even become so violent that one of the opponents meets its death due to severe abdominal or thoracic wounds. [12] A silent animal, the waterbuck makes use of flehmen response for visual communication and alarm snorts for vocal communication. Waterbuck often enter water to escape from predators which include lions, spotted hyenas, leopards, cheetahs, African wild dogs and Nile crocodiles (leopards and hyenas prey on juveniles). [16] However, it has been observed that the waterbuck does not particularly like being in water. [21] Waterbuck may run into cover when alarmed, and males often attack predators. [12]
Waterbucks are susceptible to ulcers, lungworm infections, and kidney stones. Other diseases from which these animals suffer are foot-and-mouth disease, sindbis fever, yellow fever, bluetongue, bovine virus diarrhoea, brucellosis, and anthrax. They are more resistant to rinderpest than are other antelopes. They are unaffected by tsetse flies [22] because they produce volatiles which act as repellents. Waterbuck odor volatiles are under testing and development as repellents to protect livestock. [23] [24] : Suppl T1 However ticks may introduce parasitic protozoa such as Theileria parva , Anaplasma marginale , and Baberia bigemina ; 27 species of ixodid ticks have been found on waterbucks - a healthy waterbuck may carry over 4000 ticks in their larval or nymphal stages, the most common among them being Amblyomma cohaerens and Rhipicephalus tricuspis . Internal parasites found in waterbuck include tapeworms, liver flukes, stomach flukes, and several helminths. [16] [25]
The waterbuck exhibits great dependence on water. It can not tolerate dehydration in hot weather, and thus inhabits areas close to sources of water. However, it has been observed that unlike the other members of its genus (such as the kob and puku), the waterbuck ranges farther into the woodlands while maintaining its proximity to water. [21] With grasses constituting a substantial 70 to 95 percent of the diet, the waterbuck is predominantly a grazer frequenting grasslands. Reeds and rushes like Typha and Phragmites may also be preferred. [16] A study found regular consumption of three grass species round the year: Panicum anabaptistum , Echinochloa stagnina and Andropogon gayanus . Hyparrhenia involucrata , Acroceras amplectens and Oryza barthii along with annual species were the main preference in the early rainy season, while long life grasses and forage from trees constituted three-fourths of the diet in the dry season. [26]
Though the defassa waterbuck was found to have a much greater requirement for protein than the African buffalo and the Beisa oryx, the waterbuck was found to spend much less time on browsing (eating leaves, small shoots, and fruits) in comparison to the other grazers. In the dry season, about 32% of the 24-hour day was spent in browsing, whereas no time was spent on it during the wet season. The choice of grasses varies with location rather than availability; for instance, in western Uganda, while Sporobolus pyramidalis was favoured in some places, Themeda triandra was the main choice elsewhere. The common waterbuck and the defassa waterbuck in the same area may differ in their choices; while the former preferred Heteropogon contortus and Cynodon dactylon , the latter showed less preference for these grasses. [16]
Waterbuck are slower than other antelopes in terms of the rate of maturity. [12] While males become sexually mature at the age of six years, females reach maturity within two to three years. [11] Females may conceive by the age of two-and-a-half years, and remain reproductive for another ten years. [16] In equatorial regions, breeding takes place throughout the year, and births are at their peak in the rainy season. However, breeding is seasonal in the Sudan (south of Sahara), with the mating season lasting four months. The season extends for even longer periods in some areas of southern Africa. Oestrus lasts for a day or less. [12]
Mating begins after the male confirms that the female is in oestrus, which he does by sniffing her vulva and urine. A resistive female would try to bite or even fight off an advancing male. The male exhibits flehmen, and often licks the neck of the female and rubs his face and the base of his horns against her back. There are several attempts at mounting before the actual copulation. The female shifts her tail to one side, while the male clasps her sides with his forelegs and rests on her back during copulation, which may occur as many as ten times. [7] [12]
The gestational period lasts for seven to eight months, followed by the birth of a single calf. Twins are rare. Pregnant females isolate themselves in thickets as parturition approaches. Newborn calves can stand on their feet within a half-hour of birth. [11] The mother eats the afterbirth. She communicates with the calf by bleating or snorting. [7] Calves are kept hidden from two to three weeks up to two months. At about three to four weeks, the calf begins following its mother, who signals it to do so by raising her tail. Though bereft of horns, mothers will fiercely defend their offspring from predators. Calves are weaned at eight months, following which time they join groups of calves of their own age. [12] Young females remain with their mothers in nursery herds, or may also join bachelor herds. [7] The waterbuck lives to 18 years in the wild and 30 years in captivity. [16]
The waterbuck is native to southern and eastern Africa (including countries such as Angola, Botswana, The Democratic Republic of Congo, Ethiopia, Kenya, Namibia, South Africa, Tanzania and Uganda) besides a few countries of western and northern Africa such as Chad, Côte d'Ivoire, Ghana, Mali, Niger, Nigeria and Senegal. Though formerly widespread in sub-Saharan Africa, its numbers have now decreased in most areas. [1]
The common waterbuck is found east of the Eastern African Rift. Its southern range extends to the Hluhluwe-Umfolozi Game Reserve (KwaZulu Natal) and to central Namibia. By contrast, the defassa waterbuck inhabits western and central Africa. The defassa waterbuck occurs west of the Albertine Rift and ranges from Eritrea to Guinea Bissau in the southern Sahel, its most northerly point of distribution being in southern Mali. Its range also stretches east of the Congo basin through Zambia into Angola, while another branch extends to the Zaire River west of the Congo basin. While the common waterbuck is now extinct in Ethiopia, the defassa waterbuck has become extinct in Gambia. [1]
Waterbuck inhabit scrub and savanna areas alongside rivers, lakes and valleys. [13] Due to their requirement for grasslands as well as water, the waterbuck have a sparse distribution across ecotones (areas of interface between two different ecosystems). A study in the Ruwenzori Range showed that the mean density of waterbuck was 5.5 per square mile, and estimates in the Maasai Mara were as low as 1.3 per square mile. It has been observed that territorial size depends on the quality of the habitat, the age and health of the animal and the population density. The greater the age of the animal or the denser the populations, the smaller are the territories. In Queen Elizabeth National Park, females had home ranges 21–61 hectares (0.081–0.236 sq mi ; 52–151 acres ) in area whereas home ranges for bachelor males averaged between 24–38 hectares (0.093–0.147 sq mi ; 59–94 acres ). The oldest female (around 18 years old) had the smallest home range. [12]
The International Union for the Conservation of Nature and Natural Resources (IUCN) lists the waterbuck as of least concern (LC). More specifically, the common waterbuck is listed as of Least Concern while the defassa waterbuck is near threatened (NT). The population trend for both the common and defassa waterbuck is decreasing, especially that of the latter, with large populations being eliminated from their habitats due to poaching and human settlement. Their own sedentary nature too is responsible for this to some extent. Numbers have fallen in Queen Elizabeth National Park, Murchison Falls National Park, Akagera National Park, Lake Nakuru National Park, and Comoé National Park. [1] Population decrease in the Lake Nakuru National Park has been attributed to heavy metal poisoning. While cadmium and lead levels were dangerously high in the kidney and the liver, deficiencies of copper, calcium and phosphorus were noted. [27]
Over 60 percent of the defassa waterbuck populations thrive in protected areas, most notably in Niokolo-Koba, Comoe, Mole, Bui, Pendjari, Manovo-Gounda St. Floris, Moukalaba-Doudou, Garamba, Virunga, Omo, Mago, Murchison Falls, Serengeti, and Katavi, Kafue and Queen Elizabeth National Parks, the national parks and hunting zones of North Province (Cameroon), Ugalla River Forest Reserve, Nazinga Game Ranch, Rukwa Valley, Awash Valley, Murule and Arly-Singou. The common waterbuck occurs in Tsavo, Tarangire, Mikumi, Kruger and Lake Nakuru National Parks, Laikipia, Kajiado, Luangwa Valley, Selous and Hluhluwe-Umfolozi game reserves and private lands in South Africa. [1] [16]
Scientists with the ICIPE have developed tsetse-fly-repellant collars for cattle based on the smell of the waterbuck. [28]
The impala or rooibok is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus Aepyceros, and tribe Aepycerotini, it was first described to Europeans by German zoologist Hinrich Lichtenstein in 1812. Two subspecies are recognised—the grassland-dwelling common impala, and the larger and darker black-faced impala, which lives in slightly more arid, scrubland environments. The impala reaches 70–92 cm (28–36 in) at the shoulder and weighs 40–76 kg (88–168 lb). It features a glossy, reddish brown coat. The male's slender, lyre-shaped horns are 45–92 cm (18–36 in) long.
The sitatunga or marshbuck is a swamp-dwelling medium-sized 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 mostly 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.
The greater kudu is a large woodland antelope, found throughout eastern and southern Africa. Despite occupying such widespread territory, they are sparsely populated in most areas due to declining habitat, deforestation, and poaching. The greater kudu is one of two species commonly known as kudu, the other being the lesser kudu, T. imberbis.
The sable antelope is a large antelope which inhabits wooded savanna in East and Southern Africa, from the south of Kenya to South Africa, with a separated population in Angola.
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 common tsessebe or sassaby is the southern, nominate subspecies of Damaliscus lunatus, although some authorities have recognised it as an independent species. It is most closely related to the Bangweulu tsessebe, sometimes also seen as a separate species, less to the topi, korrigum, coastal topi and tiang subspecies of D. lunatus, and less to the bontebok in the same genus. Common tsessebe are found in Angola, Zambia, Namibia, Botswana, Zimbabwe, Eswatini, and South Africa.
The hartebeest, also known as kongoni or kaama, is an African antelope. It is the only member of the genus Alcelaphus. Eight subspecies have been described, including two sometimes considered to be independent species. A large antelope, the hartebeest stands just over 1 m at the shoulder, and has a typical head-and-body length of 200 to 250 cm. The weight ranges from 100 to 200 kg. It has a particularly elongated forehead and oddly-shaped horns, a short neck, and pointed ears. Its legs, which often have black markings, are unusually long. The coat is generally short and shiny. Coat colour varies by the subspecies, from the sandy brown of the western hartebeest to the chocolate brown of the Swayne's hartebeest. Both sexes of all subspecies have horns, with those of females being more slender. Horns can reach lengths of 45–70 cm (18–28 in). Apart from its long face, the large chest and the sharply sloping back differentiate the hartebeest from other antelopes. A conspicuous hump over the shoulders is due to the long dorsal processes of the vertebrae in this region.
The kob is an antelope found across Central Africa and parts of West Africa and East Africa. Together with the closely related reedbucks, waterbucks, lechwe, Nile lechwe, and puku, it forms the Reduncinae tribe. Found along the northern savanna, it is often seen in Murchison Falls and Queen Elizabeth National Park, Uganda; Garamba and Virunga National Park, and the Democratic Republic of the Congo, as well as grassy floodplains of South Sudan. Kob are found in wet areas, where they eat grasses. Kob are diurnal, but inactive during the heat of the day. They live in groups of either females and calves or just males. These groups generally range from five to 40 animals.
The lechwe, red lechwe, or southern lechwe is an antelope found in wetlands of south-central Africa.
The Nile lechwe or Mrs Gray's lechwe is an endangered species of antelope found in swamps and grasslands in South Sudan and Ethiopia.
The puku is a medium-sized antelope found in wet grasslands in southern Democratic Republic of Congo, Namibia, Tanzania, Zambia and more concentrated in the Okavango Delta in Botswana. Nearly one-third of all puku are found in protected areas, zoos, and national parks due to their diminishing habitat.
The bohor reedbuck is an antelope native to central Africa. The animal is placed under the genus Redunca and in the family Bovidae. It was first described by German zoologist and botanist Peter Simon Pallas in 1767. The bohor reedbuck has five subspecies. The head-and-body length of this medium-sized antelope is typically between 100–135 cm (39–53 in). Males reach approximately 75–89 cm (30–35 in) at the shoulder, while females reach 69–76 cm (27–30 in). Males typically weigh 43–65 kg (95–143 lb) and females 35–45 kg (77–99 lb). This sturdily built antelope has a yellow to grayish brown coat. Only the males possess horns which measure about 25–35 cm (9.8–13.8 in) long.
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.
The common duiker, also known as the gray duiker or bush duiker, is a small antelope and the only member of the genus Sylvicapra. This species is found everywhere in Africa south of the Sahara, excluding the Horn of Africa and the rainforests of the central and western parts of the continent. Generally, they are found in habitats with sufficient vegetation cover to allow them to hide—savannah and hilly areas, including the fringes of human settlements.
The blue wildebeest, also called the common wildebeest, white-bearded gnu or brindled gnu, is a large antelope and one of the two species of wildebeest. It is placed in the genus Connochaetes and family Bovidae, and has a close taxonomic relationship with the black wildebeest. The blue wildebeest is known to have five subspecies. This broad-shouldered antelope has a muscular, front-heavy appearance, with a distinctive, robust muzzle. Young blue wildebeest are born tawny brown, and begin to take on their adult coloration at the age of 2 months. The adults' hues range from a deep slate or bluish-gray to light gray or even grayish-brown. Both sexes possess a pair of large curved horns.
The Ugandan kob is a subspecies of the kob, a type of antelope. It is found in sub-Saharan Africa in South Sudan, Uganda and the Democratic Republic of the Congo. The Ugandan kob is normally reddish-brown, differentiating it from other kob subspecies.
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.
The wildlife of Kenya refers to its fauna. The diversity of Kenya's wildlife has garnered international fame, especially for its populations of large mammals. Mammal species include lion, cheetah hippopotamus, African buffalo, wildebeest (Connochaetes), African bush elephant, zebra (Equus), giraffe (Giraffa), and rhinoceros. Kenya has a very diverse population of birds, including flamingo and common ostrich.
The Cape lechwe or Venter's lechwe is an extinct species similar to the red lechwe, Kobus leche. It was described by Robert Broom from a frontlet and horn core from Haagenstad, which Broom believed to be an intermediate form between lechwe and waterbuck. However others have failed to find justification for separating the species from Kobus leche.
The Mbéré Valley National Park is a national park in eastern-central Cameroon.
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