Waterbuck

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Waterbuck
Male K. e. defassa
Queen Elizabeth National Park, Uganda
Female K. e. ellipsiprymnus
Chobe National Park, Botswana

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this 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

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.

gestational period
lasts 7–8 months, followed by the birth of a single calf.

Waterbucks inhabit

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.

Taxonomy and etymology

Common waterbuck in Botswana

The

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

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]

Evolution

Not many fossils of the waterbuck have been found. Fossils were scarce in the

East African Rift Valley to the west.[3]

Subspecies

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]

  • K. e. ellipsiprymnus (ellipsen waterbuck, common or ringed waterbuck) group: Found in the Webi Shebeli river valley in southeastern Ethiopia; the Juba and Webi Shebeli river valleys in Somalia; essentially east of the Rift Valley in Kenya and Tanzania; east of the Rift Valley in the middle Zambezi and Luangwa valleys in Zambia; Malawi; Mozambique; east of the Kwando River in the Caprivi Strip of Namibia; eastern and northern Botswana; Zimbabwe; and eastern and northern Transvaal in South Africa. Its distribution slightly overlaps that of the typical defassa along the Rift Valley in Kenya and Tanzania, and that of the Crawshay defassa in the Rift Valley in Zambia.
Includes the following four subspecies:
Includes the following subspecies:
  • Angolan defassa waterbuck (K. e. penricei) W. Rothschild, 1895 Can be found in Southern Gabon, southern Congo (Brazzaville), Angola, southwestern Congo (Kinshasa), and marginally in Namibia along the Okavango River.
  • Crawshay defassa waterbuck or Rhodesian defassa waterbuck (K. e. crawshayi) P. L. Sclater, 1894 (including K. e. uwendensis, K. e. frommiand K. e. münzneri) Can be found in Zambia, from the upper Zambezi River eastward to the Muchinga escarpment (which is a southern extension of the Great Rift Valley). Also in adjoining parts of Katanga Province in Congo (Kinshasa).
  • East African defassa waterbuck
  • K. e. adolfi-friderici Matschie, 1906 (including K. e. fulvifrons, K. e. nzoiae and K. e. raineyi) (northeastern Tanzania west of the Rift Wall, and north into Kenya)
  • K. e. defassa Rüppell, 1835 (including K. e. matschiei and K. e. hawashensis) (central and southern Ethiopia)
  • K. e. harnieri Murie, 1867 (including K. e. avellanifrons, K. e. ugandae, K. e. dianae, K. e. ladoensis, K. e. cottoni, K. e. breviceps, K. e. albertensis and K. e. griseotinctus) (northeastern Congo [Kinshasa], Sudan, western Ethiopia, Uganda, western Kenya, Rwanda, Burundi and northwestern Tanzania)
  • K. e. tjäderi Lönnberg, 1907 (including K. e. angusticeps and K. e. powelli) (Laikipia Plateau in Kenya)
  • Sing-sing waterbuck
  • K. e. annectens Schwarz, 1913 (including K. e. schubotzi) (C.A.R.)
  • K. e. tschadensis Schwarz, 1913 (Chad)
  • K. e. unctuosus Laurillard, 1842 (including K. e. togoensis) (Cameroon west to Senegal)

Description

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.

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]

Ecology and behaviour

A female herd in the Samburu National Park (Kenya)

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

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

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]

Diseases and parasites

Waterbucks are susceptible to

helminths.[16][25]

Diet

The waterbuck is predominantly a grazer.

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

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]

Reproduction

A female waterbuck with her young

Waterbuck are slower than other antelopes in terms of the rate of maturity.

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

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]

Distribution and habitat

Waterbuck inhabit grasslands close to water.

The waterbuck is native to southern and eastern Africa (including countries such as

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

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.

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]

Threats and conservation

The International Union for the Conservation of Nature and Natural Resources (IUCN) lists the waterbuck as of

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

Luangwa Valley, Selous and Hluhluwe-Umfolozi game reserves and private lands in South Africa.[1][16]

Research

Scientists with the ICIPE have developed tsetse-fly-repellant collars for cattle based on the smell of the waterbuck.[28]

References

  1. ^
    doi:10.2305/IUCN.UK.2016-2.RLTS.T11035A50189324.en
    . Retrieved 19 November 2021.
  2. ^ "Defassa Waterbuck Facts and Information | SeaWorld Parks & Entertainment". seaworld.org. Retrieved 2023-06-06.
  3. ^
    ISBN 0-12-657720-X
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  4. ^ a b c d Huffman, B. "Waterbuck". Ultimate Ungulate. Retrieved 21 March 2014.
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    ISBN 0521844185
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  9. S2CID 85008015
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  10. OCLC 62265494
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  11. ^ a b c d Newell, T. L. "Kobus ellipsiprymnus (Waterbuck)". University of Michigan Museum of Zoology. Animal Diversity Web. Retrieved 21 March 2014.
  12. ^
    ISBN 0-520-08085-8
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  13. ^
    ISBN 0-226-43724-8
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  14. ^ "Waterbuck". African Wildlife Foundation. Retrieved 29 January 2017.
  15. ISBN 978-1-4214-0093-8
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  16. ^ a b c d e f g h i j Kingdon, J.; Hoffman, M. Mammals of Africa (Volume VI): Hippopotamuses, Pigs, Deer, Giraffe and Bovids. Bloomsbury. pp. 461–8.
  17. ^ Melton, D. A. (1978). Ecology of waterbuck Kobus ellipsiprymnus (Ogilby, 1833) in the Umfolozi Game Reserve (PDF). Pretoria: University of Pretoria.
  18. ^
    doi:10.1111/j.1469-7998.1969.tb08452.x
    .
  19. S2CID 29277312
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  20. doi:10.1111/j.1439-0310.1982.tb00322.x
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  21. ^
    ISBN 0-8018-5789-9
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  22. PMID 5340724
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  23. PMID 34283848. {{cite journal}}: External link in |author3= (help)CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
    )
  24. S2CID 23463014
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  25. S2CID 31618196
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  26. hdl:2268/117092
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  27. S2CID 13736671
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  28. ^ Ali, Laila (15 January 2013). "How the stink of a waterbuck could prevent sleeping sickness in Kenya". The Guardian. Mombasa. Retrieved 12 March 2015.
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External links

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