Sitatunga

They are a medium-sized antelope. It is sexually dimorphic, with males considerably larger than females. The head-and-body length is typically between 136–177 cm in males and 104–146 cm in females. Males reach approximately 81–116 cm at the shoulder, while females reach 72–90 cm. Males typically weigh 76–119 kg, while females weigh 24–57 kg. The tail is 14–37 cm long. The saucer-shaped ears are 11–17 cm long. Only the males possess horns; these are spiral in shape, have one or two twists and are 45–92 cm long. The coat colour varies geographically, but, in general, is a rufous red in juveniles and chestnut in females.

There are white facial markings, as well as several stripes and spots all over, though they are only faintly visible. White patches can be seen on the throat, near the head and the chest. A pair of inguinal scent glands are present. Males develop a rough and scraggy mane, usually brown in colour, and a white dorsal stripe. There is a chevron between the eyes of the males. The body and legs of this antelope are specially adapted to its swampy habitat. The hooves of the male are elongated and widely splayed. The rubbery, shaggy, water-repellent coat is minimally affected by slimy and muddy vegetation. The wedge-like shape and lowering of the head, coupled with the backward bend of the horns (in males) provides for easy navigation through dense vegetation. The pointed toes allow it to walk slowly and almost noiselessly through the water. The colour of the coat provides excellent camouflage. Hearing is acute, and the ears are so structured that the animal can accurately determine the direction from where a sound has originated. This adaptation is of profound use in habitats where long sight is of very little value due to the density and darkness of the environment.

three distinct subspecies are currently recognised:

Nile sitatunga or East African sitatunga. Found in the Nile watershed.
Congo sitatunga or forest sitatunga. Found in western and central Africa.
Southern sitatunga or Zambezi sitatunga. Found in southern Africa.

Habitat

The sitatunga is an amphibious antelope (meaning it can live on both land and water) confined to swampy and marshy habitats. They occur in the tall and dense vegetation of perennial as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps. Sitatunga moves along clearly marked tracks in their swampy habitat, often leading to reed beds. These tracks, up to 7 m wide, can lead to feeding grounds and nearby riverine forests. The sitatunga holds small home ranges near water bodies. In savannas, they are typically found in stands of papyrus and reeds.

The sitatunga is native to Angola, Benin, Botswana, Burundi, Cameroon, Central African Republic, Chad, The Democratic Republic of the Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Mozambique, Namibia, Nigeria, Rwanda, Senegal, South Sudan, Tanzania, Uganda, Zambia and Zimbabwe. While it is localised and sporadic in western Africa, the sitatunga is still common in the forests of central Africa and certain swampy regions in central, eastern and southern Africa.

Diet

Sitatunga are selective and mixed feeders. They feed mainly on new foliage, fresh grasses, sedges and browse. They feed mostly in the wetland fringes. Diet preferences may vary seasonally in swamps where water levels change notably. A study recorded forty major species eaten by the animal, the majority of which were herbs. The sweet potato was the most preferred crop. The study predicted an increase in preference for crops due to seasonal food variations. Another study showed that annual floods affect the seasonal movement and diet of the species. These floods force the animals out of the reed beds onto the flooded grasslands when the water levels are high. At low water levels, the cattle take over the flooded plains and send the sitatunga back to their original place.

Breeding

Females are sexually mature by one year of age, while males take one-and-a-half-year before they mature. Breeding occurs throughout the year. When females gather, the males compete among each other for the right to mate, showing polygyny in males. The rutting male approaches the female in a lower bending posture, sniffing her vulva. The female may move slowly or react nervously. Even if the female flees, the male continues pursuing her steadily, without showing any sign of hurry. A receptive female will raise her head with her mouth wide open, following which the male will begin attempts at mounting. At the time of mounting the female lowers her head, while the male first bends and then straightens his forelegs and rests his head and neck on her back. The two remain together for one or two days, during which time the male ensures that no other male can approach the female. Gestation lasts for nearly eight months, after which generally a single calf is born. Parturition occurs throughout the year, though a peak may occur in the dry season. Calves are hidden adroitly and brought out of cover only in the presence of many other sitatungas. The mother gazes and nods at the calf to summon it for nursing. A calf follows its mother about even after she has given birth to another calf. The mother suckles and licks her calf for about six months. The calf takes time to master the specialised gait of the sitatunga, and thus often loses its balance and falls in the water. Males, and even some females, have been observed to leave their herds even before reaching sexual maturity due to intrasexual competition. Lifespan recorded in captivity averages 22 to 23 years.

Population

According to the IUCN Red List, they are classed as Least Concern(LC) and their population trend is decreasing. The amount of mature individuals is estimated at around 90,000-120,000.

Threats

Loss of habitat is the main threat to the future persistence of Sitatunga. The ever-increasing loss of wetlands throughout their range has cut off former routes of dispersal and many populations are becoming isolated. Sitatunga is vulnerable to long-term changes in water level because it alters vegetation structure, which in turn largely determines their distribution and abundance. Habitat fragmentation and both lower and higher water levels make them more vulnerable to predation and meat hunting in many parts of its range. Swamps are also extremely vulnerable to fire; vast areas of Bangweulu and Busanga are burnt each year. Nonetheless, the Sitatunga shows a remarkable ability to survive near human habitation, provided suitable habitat remains.

Conservation

About 40% of the population survives in and around protected areas, with major, generally stable populations occurring in Dja and Lobeke (Cameroon), Bangassou (Central African Republic), Odzala N.P. and L. Tele-Likouala (Republic of Congo), Salongo N.P. (DR Congo), Bangweulu and Busanga Swamps (Zambia), Okavango Delta (Botswana), and Akagera N.P. (Rwanda). At present, only a few of these areas receive moderate-high levels of protection and management. The current survival of good Sitatunga populations in other areas, such as Lobeke, Bangweulu and Okavango, is a product of low human population densities rather than active conservation. The large areas of swamp within the Okavango Delta currently provide the Sitatunga with a safe refuge (from hunting in particular) to persist in. They should continue to do so, as long as the ecology of the Delta is not altered significantly by factors such as cattle grazing within the swampland, uncontrolled burning, overhunting and hydrological schemes that would affect the water levels in the perennial or seasonal swamps. Moremi Game Reserve contains a limited area of the permanent swamp with moderate numbers of Sitatunga, but proposals to incorporate the Xo Flats within this reserve would significantly increase the protected population of this antelope. The species’ significance as a trophy animal is an important economic incentive for the conservation of its habitat, and hunting zones adjoining national parks and equivalent reserves have the potential to play an increasingly important role in the conservation of the Sitatunga.