Kobus smithemani (Lydekker, 1900)
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publication ID |
https://doi.org/10.5281/zenodo.6512484 |
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persistent identifier |
https://treatment.plazi.org/id/03F50713-9972-FFCA-06DE-F2AFF8AEF8D4 |
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treatment provided by |
Conny |
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scientific name |
Kobus smithemani |
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Black Lechwe
French: Cobe du Bangweulu / German: Bangweulu-Litschi / Spanish: Kob negro
Taxonomy. Cobus smithemani Lydekker, 1900 , neighbourhood of Lake Mweru.
The Black Lechwe was formerly included as a subspecies of K. leche . Monotypic.
Distribution. Endemic to the Bangweulu Basin in C Zambia. View Figure
Descriptive notes. Head-body c¢.160-180 cm, tail ¢.30-45 cm; weight 45-75 kg (males) and 40-60 kg (females). Body condition tends to be lowest in the late dry season, from August to November, when food resources are at their lowest. The Black Lechwe displays sexual dimorphism in both size and color: males are larger and darker. Females and juveniles are generally rufous; the flanks tend to be paler than the dorsal surface. The belly and inner surfaces of the legs are white; along the flanks, the white underparts and rufous upperparts abut in a sharp line. A narrow pale stripe runs along the underside of the neck from the throat to the chest. Dark stripes are present on the front of the forelegs. The tail has a bushy black tip. The face has the same overall coloration as the body, with white markings on the lips and above (and less distinctly behind and below) the eyes; the insides of the ears are also white. As males mature, the reddish areas darken to brownish-black, accentuating the white markings. The infusion of black hairsis first apparent on the shoulders, and subsequently extends up the throat (on either side of the white stripe) to the lower cheeks as well as encompassing the entire outer surfaces of the forelegs (the inner surfaces remain bright white). The lower flanks follow, strengthening the demarcation with the white underparts before gradually spreading dorsally. There is considerable variation in the extent of this dark coloration between individual males as well as between seasons. In mature males, the entire body may be rich brownish-black, although rufous patches typically remain on the forehead and upper neck, the rump, and the upper hindlegs in even the darkest individuals. This coloration is thought to develop during, and regress after, the breeding season: dark males are seen in significantly higher numbers at this time. Aside from their coloration, males are easily identified by the presence of lyre-shaped horns. The horns are relatively short compared to other lechwes, but have a stronger curve. From the skull, the horns first bend backward, then upward and forward toward the tips. Twenty to 25 rings are present along the length of each horn, which may grow 51-615 cm in good specimens. Dental formulais 10/3, C0/1,P 3/3, M 3/3 (x2) = 32.
Habitat. Edges of permanent swamps, seasonally inundated floodplains, and associated peripheral grasslands. Black Lechwes congregate in areas covered in shallow water 2-6 cm deep, and follow the seasonal rise and fall of water levels to remain in their preferred habitat. Water deeper than 60 cm is generally avoided, although it may be sought as refuge to escape from Spotted Hyena (Crocuta crocuta), the principal natural predator. Temporary dispersal into drier habitats may be induced by sporadic heavy rainfall. During the dry season, the Black Lechwe is found in permanently flooded areas dominated by grass genera including Oryza, Typha, Phragmites, and Miscanthus; in peak drought conditions, permanent swamps and areas dominated by Vossia and Eleocharis are used. Wet season habitats are best represented by shallow-water floodplains of Oryza, Acroceras, Leersia, Echinochloa, Paspalum, and Sacciolepis grasses. Drier intermediate grasslands (with grasses Themeda, Setaria, and Loudetia) are most used when floods are highest, and are easily recognized by the presence of termite mounds. As a result of variations in habitat availability and seasonal movements, localized population densities are highly variable. Floodplain density of 22 ind/km? has been recorded at the end of the dry season (October); the same region may support 135 ind/km?® during the wet season (January).
Food and Feeding. A selective grazer, the Black Lechwe feeds primarily on the leaves of wetland grasses. Soft green grasses are preferred, although more grass stems are eaten with increased frequency during the dry season. The grass Echinochloa stagnina is consumed in large quantities throughout most of the year, and may account for 60% of food consumed in the wet season. Other grasses are preferentially consumed at different times of the year, including Acroceras macrum (January-June), Leersia hexandra (January-August) , and Vossia cuspidata (July-December) . Oryza barthii and Eleocharis sedges are most frequently eaten during the dry season. The high water content of wetland grasses eliminates the need to drink water.
Breeding. Seasonal. The breeding season (rut) begins in December, with reproductive activities peaking in mid-February and continuing until late March or early April. The Black Lechwe is polygynous; successful males occupy territories with raised ground (used for resting), which is thought to attract females. The gestation period is approximately 260 days; births occur between November and January, coinciding with the start of the rainy season. Pre-parturient females isolate themselves and move into deeper swamps, where the single offspring is born in a protected papyrus thicket or other well-vegetated area. The neonate remains hidden for a few days, with the mother close by, especially at night. After the infantis stable on its feet, mother and offspring return to floodplain grazing areas. Nursing occurs at least four times per day, with each interval lasting around five minutes. The bond between mother and infant is loose; infants frequently congregate in nursery groups and only occasionally associate with their mothers. Weaning has not been well documented, but two isolated observations suggest it occurs at approximately three months; at approximately this time, dams will typically conceive again. Females reach sexual maturity at about one year of age; approximately 67% of yearling females (1-2 years old) are pregnant. Timing of male sexual maturity is less well understood. Horn growth begins at six months of age and the mature shape is achieved by four years, although the horns continue to grow until age seven. Mature coloration is achieved at four years of age. It is unlikely that young males (even if sexually mature) are able to successfully compete for territories and mates before this time.
Activity patterns. The Black Lechwe is thought to be active both day and night, although most studies have only observed this species during daylight hours. Feeding activity is highest in the morning, gradually waning from a peak at 06:00 h until 12:00 h. Midday is spent resting; individuals will lie down if dry ground is available, but in flooded pastures all remain standing. Feeding activity increases again between 17:00 h and 18:00 h and may continue after sunset. Social behaviors are most frequent in the afternoon, especially 14:00-16:00 h. In the dry season, days are typically spent in open areas, with herds retreating into denser swamp vegetation at the waterline for the night. Such vegetation is not available during the wet season; herds remain on the open floodplains day and night.
Movements, Home range and Social organization. Water levels define the seasonal migrations of the Black Lechwe. Unusual among ungulates, populations are more concentrated during the wet season (December—April) than during the dry season. Herd structure is poorly understood, but it appears to be relatively loose and lacking cohesion. Large herds containing both sexes are most common during the wet season, with the average herd size peaking at 2500 animals in March. During the dry season (from June through January), herd size is usually less than 500. Small herds ofless than ten females may be seen during the early wet season as they move to central swamps in order to give birth. Bachelor herds are also common during the wet season, and are most frequently seen on peripheral grasslands, since territorial males displace them from floodplain areas. Territoriality occurs only during the breeding season; defended territories are 0-005-0-02 km?, and are often clustered around raised dry islands within flooded habitats. These territories are vigorously defended: fights between males may result in severe injury or death. However, aggressive encounters in bachelor herds are extremely rare. Dry season groups show less stratification between the sexes.
Status and Conservation. CITES Appendix II (under K. leche ). Classified as Vulnerable on The IUCN Red List (as K. leche smithemani). Early 20" century counts estimated 200,000 Black Lechwes within the Bangweulu basin, but only 16,500 were counted in 1971. Illegal hunting is believed to be a principal cause of this decline, as well as a shift in distribution away from areas of human occupation near Lake Bangweulu. In recent decades, Black Lechwe numbers have stabilized at approximately 30,000 individuals, split among five principal subpopulations around Lake Bangweulu. The available habitat there is thought to be able to support over 150,000 animals; ongoing hunting pressures are believed to be the principal limiting factor, because predators and disease are relatively minor pressures. Ongoing protection efforts such as the formation of protected wetland areas and work within local communities may permit the population to increase in coming decades.
Bibliography. East (1999), Howard et al. (1984), IUCN/SSC Antelope Specialist Group (2008ae), Kamweneshe (2000), Lydekker (1914), Thirgood et al. (1992).
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