The sitatunga ( Tragelaphus spekii) 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 South 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. They occur in tall and dense vegetation as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps.
Speke had stated in a footnote in his book that the species had been named Tragelaphus spekii by English zoologist Philip Sclater. However, according to the International Code of Zoological Nomenclature (Article 50.1.1) and the International Commission on Zoological Nomenclature, which acknowledge the person who first described the species, simply declaring Sclater as the authority in a footnote is insufficient to recognise him as the author. Hence, Speke was recognised as the correct authority and T. spekii (where spekii is the genitive of the "Spekius") was considered the correct name for the species.
The sitatunga is placed under the genus Tragelaphus and in the family Bovidae. In 2005, Sandi Willows-Munro of the University of KwaZulu-Natal (Durban) carried out a analysis of the nine Tragelaphus species. mtDNA and nDNA data were compared. The results showed that sitatunga plus bongo ( T. eurycerus) form a monophyletic clade with the mountain nyala ( T. buxtoni) and bushbuck ( T. scriptus). The greater kudu ( T. strepsiceros) split from this clade approximately 8.6 million years ago.
Within Tragelaphus, the bushbuck, bongo, sitatunga and nyala ( T. angasii) are particularly close relatives. The bushbuck and sitatunga are genetically similar enough to hybridise. Hybrids between bongo and sitatunga have proved to be fertile. The sitatunga is more variable in its general characters than any other member of the tribe Strepsicerotini, that consists of the genera Taurotragus (elands) and Tragelaphus, probably because of their confinement to swampy and marshy habitats.
On the basis of physical characteristics such as hair texture, coat colour and the coat stripes, up to ten subspecies of the sitatunga have been described. However, these factors may not be reliable since hair texture could vary with the climate, while pelage colour and markings vary greatly among individuals. Moreover, the coat might darken and the stripes and spots on it might fade with age, especially in males. The species might even be monotypic, however, based on different drainage systems, three distinct subspecies are currently recognised:
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 are present. The coats of males darken with age, becoming gray to dark brown. 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 are flexible, and the hooves, banana-like in shape,
The sitatunga is not territorial. Males may engage in locking horns with other males and attacking vegetation using their horns. They may perform feinting by raising their forelegs with the hindlegs rooted in the ground as a threat display. Sitatunga interact with each other by first touching their noses, which may be followed by licking each other and nibbling. Alarmed animals may stand motionless, with the head held high and one leg raised. Sitatunga may occasionally emit a series of coughs or barks, usually at night, which may cause other animals to join in, and these sounds can be heard across the swamp. This barking may be used by females to warn off other females. Males often utter a low bellow on coming across a female or a herd of females in the mating season. A low-pitched squeak may be uttered while feeding. Mothers communicate with their calves by bleats.
Sitatunga can feed or rest close to southern lechwe herds, but do not interact with them. They often attract yellow-billed oxpeckers, and . Sitatunga are good swimmers, but limit themselves to water with profuse vegetation in order to escape . In some cases, for instance when troubled by flies or pursued by predators, the sitatunga might fully submerge themselves in the water except for the nose and the eyes, which they keep slightly above the water surface. Due to its close association with water, the sitatunga are often described as "Aquatic animal antelopes", like the waterbuck.
A study recorded forty major species eaten by the animal, the majority of which were herbs. 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 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.
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 sitatunga. 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 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.
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. It is extinct in Niger, where it formerly occurred in the Lake Chad region, and is feared to be extinct in Togo, where its habitat has been taken over by dense human settlements. 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.
In Senegal, intensive hunting for meat and habitat degradation have made the sitatunga very rare. Formerly it was common throughout Gambia, but now it is confined to a few inaccessible swamps; a population has been introduced in the Abuko Nature Reserve. On the other hand, though the animal is hunted by locals primarily for food, Botswana still supports a large portion of the total population. The species is of great economic significance for northern Botswana, that produces some of the world's biggest sitatunga Trophy hunting. Its status is unclear in Chad, Ghana, Guinea, Burundi and Mozambique and Zimbabwe. Significant populations still exist in countries such as Cameroon, Central African Republic, The Democratic Republic of Congo, Equatorial Guinea, Gabon, Tanzania and Zambia. The inaccessibility of its habitat has rendered population estimates very difficult. In 1999, Rod East of the IUCN SSC Antelope Specialist Group estimated a total population of 170,000, but this is likely to be an overestimate. Its numbers are decreasing in areas of heavy human settlement, but are stable elsewhere.
Around 40 percent of the populations (based on the overestimate of 170,000) occurs in protected areas, mainly in Okavango Delta and Linyanti River and Cuando River swamps (Botswana); Dja Faunal Reserve and Lobéké National Park (Cameroon); Bangassou (Central African Republic); Odzala National Park, Lake Télé Community Reserve, Likouala River and Salonga National Park (The Democratic Republic of Congo); Monte Alén National Park (Equatorial Guinea); Saiwa Swamp National Park (Kenya); Akagera National Park (Rwanda); Moyowosi and Kigosi Game Reserves (Tanzania); Bangweulu Swamp and (Zambia). However, only a few are of these parks and reserves are well-protected and managed.
Description
Ecology and behaviour
Diet
Reproduction
Habitat and distribution
Threats and conservation
External links
|
|