Tragelaphus spekii (Speke, 1863)
Photo: Deon Furstenburg
|Afrikaans:||Waterkoedoe / Sitatunga|
IUCN Conservation Status:
Lower Risk, near threatened (LR/nt).
The sitatunga is the most aquatic antelope in Africa, and one of the
most poorly researched animals. Its Afrikaans name “water-kudu” refers
to its aquatic behaviour and its relationship to the kudu Tragelaphus
strepsiceros, but the origin of the English name sitatunga is unknown.
This genus represents all of the spiral-horned antelope of Africa and includes nine related species:
- Tragelaphus spekii, the sitatunga
- T. strepciseros, the greater kudu
- T. imberbis, the lesser kudu
- T. eurycerus, the bongo
- T. angasii, the nyala
- T. buxtoni, the mountain nyala
- T. scriptus, the bushbuck
- T. oryx, the eland
- T. derbianis, the giant or Lord Derby eland
Five sitatunga subspecies have been listed:
- T. spekii selousi, the Zambezi or southern sitatunga, also referred to as Selous’s sitatunga
- T.s. gratus, the forest or West African sitatunga
- T.s. spekii, Speke’s or East African sitatunga
- T.s. larkeni, the Nile or Sudan sitatunga
- T.s. sylvestris, from isolated islands in Lake Victoria.
The sitatunga can
crossbreed with the lesser kudu, bushbuck and bongo. Bongo hybrids are
fertile and can reproduce. Several hybrids between the subspecies of
sitatunga have been reported by zoos.
The sitatunga strongly
resembles the nyala with a woolly and water resistant coat of long hair
up to 70 mm. Subspecies differ in size with shoulder height ranging
form 75 to125 cm and body mass from 40 to120 kg, the East African form
being the smallest and the forest subspecies the largest. In common
with the nyala, sitatunga females are distinctly smaller than the
males, and referred to as ewes rather than cows. Ewes are a bright
chestnut brown and immature males a rufous-red. Bulls turn a grey
chocolate-brown to grey-black. Both sexes have characteristic white
markings on the face, ears, cheeks, body, legs and feet. Ewes have a
prominent black dorsal stripe along the spine. Bulls grow a prominent
mane around the neck. The East African bulls are grey-brown with faint
shadow stripes and silky hair; Nile bulls have exceptionally bright
stripes and thin, scanty hair; Zambezi bulls are a dull dark-brown,
lack body stripes, and have long, coarse, shaggy hair.
Comparison To Man
Only the bulls possess
horns, spiralled with 1.5-2 twists (compared to 3.5 twists for the
greater kudu bull), and 45-90 cm long. The horn buds appear at 6 months
age and are ivory tipped when fully developed.
semi-aquatic, spending their entire lives in close vicinity of open
water habitats, especially of marshes, swamps and floodplains bordering
lakes and rivers. Most essential is permanent water, evergreen
vegetation cover, and a tropical or subtropical climate. Optimal
habitat is a swamp with a water depth of up to 1 m with dense stands of
papyrus Cyperus papyrus, reed beds of Phragmites mauritianus and
Echinochloa sp and beds of bulrush Typha sp, bordered by an ecotone of
terrestrial thicket or woodland. These reeds generally stand 3-6 m
above the water surface. Areas with shrubby growth, herbs, sedges, tall
grasses and palms that border forest waterways are also favoured.
Feeding & Nutrition
Most of the daylight
hours are spend in water. In the cooler hours they feed and in the hot
midday hours they rest in the shade among reeds on platforms made of
debris or broken reed. Late at night they leave the water to browse on
neighbouring dry land, returning to the safety of the swamp before day
break. They are selective mixed feeders of water grass, sedges, water
plants and terrestrial grass, forbs and browse of shrubs and small
trees. Young papyrus and reed shoots account from 45% of the dietary
intake in the rainy season to 90% in the dry season. Browse lines have
been recorded on knob-thorn Acacia nigrescens and jackal-berry
Diospyros mespiliformis trees. They stand up straight on their hind
legs to reach the flowers and seeds of sedges and tall grasses. At
night they will invade agricultural pastures and crops. They often feed
on elephant dung as it is rich in undigested seeds.
When feeding, they are
usually solitary and spread over a large area but when alarmed they
become gregarious and aggregate while running for safety.
The population structure include Sitatungas are either solitary or occur in:
- small family groups (5-15 individuals) consisting of a bull, 2-7
ewes, and juveniles of both sexes; accounting for 4% of the population
- male/female pairs, accounting for 35% of the population
- solitary non-breeding bulls, accounting for 46% of the population
- nomadic bachelor groups of 3-4 individuals.
Juveniles often form temporary crèches of 3-5. In densely populated
habitats, family groups tend to be more tolerant of each other and
often form multiple, mass groups of up to 40 animals. A spatial
distance of at least 1-2 m is generally maintained between individuals
allowing little physical body contact. A hierarchy of dominance exists
between females in a family group. Individuals frequently interchange
between family groups, indicating a lack of tight family bonding.
Territorial behaviour is restricted to dominant bulls during the peak
periods of mating. A dominant bull residing with a family group mates
successfully with an average of four mature ewes. Sitatungas are good
swimmers, and if seriously alarmed, sink under water and swim towards
deeper water with only the nostrils showing.
|Southern Sitatunga information table
|Adult body weight
|Adult shoulder height
|Age of sexual Maturity
|Age of social adulthood (1st mating)
|1st calf born at
|Post maturity age (last mating)
(Peak in July)
|Gender ratio: natural (all ages)
|Mating ratio: natural (adults)
|Re-establishment: absolute minimum number needed
|Re-establishment: smallest viable population size
|Spatial behaviour: home range
|Spatial behaviour: territory range
|Large stock grazing unit (adult):
Dietary ratio (grass):
0.26 per animal
(65% of diet)
|0.14 per animal
(65% of diet)
|Browsing unit (adult):
Dietary ratio: (browse):
|0.65 per animal
(35% of diet)
|0.43 per animal
(35% of diet)
|Maximum stocking load
|55-200 animals per
1000 ha of optimal habitat
|Minimum habitat size required
|Annual population growth
|Optimal annual rainfall
|Optimal vegetation structure:
Woody canopy cover:
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sewlousi in the Okavango delta of Botswana. Biol. Conserv. 27:157-170.
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sitatunga hybrids Taurotragus eurycerus x Tragelaphus spekii at Antwerp
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Ungulates of the World, 2008. http://www.ultimateungulate.com.
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