Sitatunga
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The sitatunga (Tragelaphus spekii) or marshbuck<ref>Template:Cite EB1911</ref> 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 Southern 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. Here they occur in tall and dense vegetation as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps.
Taxonomy and geneticsEdit
The scientific name of the sitatunga is Tragelaphus spekii. The species was first described by the English explorer John Hanning Speke in 1863.<ref name=MSW3>Template:MSW3 Artiodactyla</ref><ref name=groves>Template:Cite book</ref> Speke first observed the sitatunga at a lake named "Little Windermere" (now Lake Lwelo, located in Kagera, Tanzania). In his book Journal of the Discovery of the Source of the Nile, Speke called the animal "nzoé" (Kiswahili name for the animal) or "water-boc" (due to its resemblance to the waterbuck).<ref name=speke/> The word "sitatunga" itself comes from an ancient Bantu language.<ref name="Gotch">Template:Cite book</ref> The scientific name has often been misstated as T. spekei, and either Speke or Sclater is referred to as the binomial authority.
Speke had stated in a footnote in his book that the species had been named Tragelaphus spekii by English zoologist Philip Sclater.<ref name=speke>Template:Cite book</ref> However, according to the International Code of Zoological Nomenclature (Article 50.1.1) and the International Commission on Zoological Nomenclature, that 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.<ref name=MSW3/> Hence, Speke was recognised as the correct authority and T. spekii (where spekii is the genitive of the Latinised "Spekius") was considered the correct name for the species.<ref name=kingdon2>Template:Cite book</ref>
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 mitochondrial 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).<ref name=cladogram>Template:Cite journal</ref> The greater kudu (T. strepsiceros) split from this clade approximately 8.6 million years ago.<ref name="ropiquet">Template:Cite journal</ref><ref name="hassanin">Template:Cite journal</ref>
Within Tragelaphus, the bushbuck, bongo, sitatunga and nyala (T. angasii) are particularly close relatives. The bushbuck and sitatunga are genetically similar enough to hybridise.<ref name=estes>Template:Cite book</ref> Hybrids between bongo and sitatunga have proved to be fertile.<ref name=hybrid1>Template:Cite journal</ref><ref name=hybrid2>Template:Cite journal</ref> 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.<ref>Template:Cite book</ref>
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.<ref name=kingdon2/> The species might even be monotypic,<ref name=kingdon2/> however, based on different drainage systems, three distinct subspecies are currently recognised:<ref>{{#if:625133 | {{#invoke:template wrapper|wrap|_template=cite web|_exclude=id,ID,taxon
| url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=625133 | title = Tragelaphus spekii | publisher = Integrated Taxonomic Information System }}
| Template:Citation error }}</ref><ref name=kingdon1>Template:Cite book</ref>
- T. s. spekii (Speke, 1863): Nile sitatunga or East African sitatunga. Found in the Nile watershed.
- T. s. gratus (Sclater, 1880): Congo sitatunga or forest sitatunga. Found in western and central Africa.
- T. s. selousi (W. Rothschild, 1898): Southern sitatunga or Zambezi sitatunga. Found in southern Africa.
DescriptionEdit
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The sitatunga is a medium-sized antelope. It is sexually dimorphic, with males considerably larger than females. The head-and-body length is typically between Template:Convert in males and Template:Convert in females. Males reach approximately Template:Convert at the shoulder, while females reach Template:Convert. Males typically weigh Template:Convert, while females weigh Template:Convert. The tail is Template:Convert long. The saucer-shaped ears are Template:Convert long.<ref name=kingdon2/> Only the males possess horns; these are spiral in shape, have one or two twists and are Template:Convert long. The sitatunga is almost indistinguishable from the nyala, except in pelage and spoor.<ref name=estes/> Speke pointed out that, though "closely allied" to the waterbuck, the sitatunga lacks stripes and is spotted instead.<ref name=speke/>
The coat colour varies geographically, but, in general, is a rufous red in juveniles and chestnut in females.<ref name=adw>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref name=nowak/> A pair of inguinal scent glands are present.<ref name=estes/> 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.<ref name=estes/> There is a chevron between the eyes of the males.<ref name=vlies>Template:Cite book</ref>
The body and legs of this antelope are specially adapted to its swampy habitat. The hooves of the male are elongated and widely splayed.<ref name=track/> 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 pasterns are flexible,<ref name=nowak>Template:Cite book</ref> and the hooves, banana-like in shape,<ref name="cranfield">Template:Cite book</ref> can reach a length of up to Template:Convert in the hindlegs and Template:Convert in the forelegs.<ref name=track>Template:Cite book</ref> The pointed toes allow it to walk slowly and almost noiselessly through the water.<ref name=williamson>Template:Cite journal</ref> Moreover, the colour of the coat provides an 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.<ref name=kingdon2/>
Ecology and behaviourEdit
Sitatunga are active mainly during the early hours after dawn, the last one or two hours before dusk, and at night,<ref name=williamson/> and spend a large part of this time feeding.<ref name=owen/> Basically sedentary, they rest in flat areas and reed beds, especially during the hotter part of the day.<ref name=games>Template:Cite journal</ref><ref name=starin>Template:Cite journal</ref> They seldom leave their swamp habitat during the daytime.<ref name=owen>Template:Cite journal</ref> Though sitatunga commonly form pairs or remain solitary, larger groups have also been observed. A study in Kenya recorded a herd of as many as nine individuals, comprising an adult male, four females and four juveniles.<ref name=estes/> Loose groups may be formed but interaction among individuals is very low.<ref name=games/> Individuals generally associate only with their own sex.<ref name=kingdon2/>
The sitatunga is not territorial. Males may engage in locking horns with other males and attacking vegetation using their horns.<ref name=starin/> 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.<ref name=kingdon2/>
Sitatunga can feed or rest close to southern lechwe herds, but do not interact with them. They often attract yellow-billed oxpeckers, African jacanas and great egrets. Sitatunga are good swimmers, but limit themselves to water with profuse vegetation in order to escape crocodiles. 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 antelopes", like the waterbuck.<ref name="bailey">Template:Cite book</ref><ref name=dudgeon/> They often dry themselves under the sun after feeding in water.<ref name=kingdon2/> Predators of the sitatunga include lions, wild dogs, crocodiles and leopards.<ref name=adw/>
DietEdit
Sitatunga are selective and mixed feeders. They feed mainly on new foliage, fresh grasses, sedges and browse. Preferred plants include: bullrushes (Typha), sedges (Cyperus), aquatic grasses (Vossia, Echinochloa, Pennisetum, Leersia, Acroceras and Panicum. Species in Umbelliferae and Acanthaceae are preferred in Saiwa Swamp National Park (Kenya), and Fabaceae species are preferred in Bangweulu and Busanga (in Kafue National Park).<ref name=owen/> They feed mostly in the wetland fringes. Diet preferences may vary seasonally in swamps where water levels change notably. Like the gerenuk, the sitatunga may stand on its hindlegs to reach higher branches of trees, or even use its horns to pull down the branches.<ref name=kingdon2/>
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.<ref name=tweheyo>Template:Cite journal</ref> 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.<ref name=games/>
ReproductionEdit
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.<ref name=magliocca/> 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.<ref name=kingdon2/>
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.<ref name=kingdon2/> 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.<ref name=estes/> Males, and even some females, have been observed to leave their herds even before reaching sexual maturity due to intrasexual competition.<ref name=magliocca>Template:Cite journal</ref> Lifespan recorded in captivity averages 22 to 23 years.<ref name=adw/>
Habitat and distributionEdit
The sitatunga is an amphibious antelope (meaning it can live on both land and water) confined to swampy and marshy habitats.<ref name=dudgeon/> They occur in tall and dense vegetation of perennial as well as seasonal swamps, marshy clearings in forests, riparian thickets and mangrove swamps.<ref name=magliocca/> Sitatunga move along clearly marked tracks in their swampy habitat, often leading to reed beds.<ref name=owen/> These tracks, up to Template:Convert wide, can lead to feeding grounds and nearby riverine forests.<ref name=estes/> The sitatunga hold small home ranges near water bodies <ref name="dudgeon">Template:Cite book</ref> In savannas, they are typically found in stands of papyrus and reeds (Phragmites species and Echinochloa pyramidalis). They share their habitat with the Nile lechwe in the Sudd swamps and with the southern lechwe in Angola, Botswana and Zambia.<ref name=iucn/>
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.<ref name=iucn/><ref name=east>Template:Cite book</ref>
Threats and conservationEdit
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Habitat loss is the most severe threat to the survival of the sitatunga. Other threats include the increasing loss of wetlands, that has isolated populations; and long-term changes in the water level, that affects the nearby vegetation and thus bears upon their diet. Vast areas of Bangweulu and Busanga are burnt every year, placing animals like the sitatunga at grave risk given the inflammability of swamps.<ref name=iucn/> The sitatunga has been classified under the Least Concern category by the International Union for Conservation of Nature and Natural Resources (IUCN),<ref name=iucn/> and under Appendix III (Ghana) of the Washington Convention (CITES).<ref name=MSW3/>
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 trophies.<ref name=iucn/><ref name=east/> 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.<ref name=east/> 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.<ref name=iucn/>
Around 40 percent of the populations (based on the overestimate of 170,000) occurs in protected areas, mainly in Okavango Delta and Linyanti and Chobe swamps (Botswana); Dja Faunal Reserve and Lobéké National Park (Cameroon); Bangassou (Central African Republic); Odzala National Park, Lake Télé Community Reserve, Likouala 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 and Busanga Swamps (Zambia). However, only a few are of these parks and reserves are well-protected and managed.<ref name=iucn/><ref name=east/>