Sitatunga

Tragelaphus spekii (Speke, 1863)

Photo: Deon Furstenburg

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.

Taxonomy

Classification

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.

Description

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

Trophy

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.

Habitat requirement

Sitatungas are 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.

Distribution

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.

Social structure

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.

Information Table

Bibliography