Redunca arundinum (Boddaert, 1785)
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publication ID |
https://doi.org/ 10.5281/zenodo.6512484 |
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DOI |
https://doi.org/10.5281/zenodo.6636834 |
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persistent identifier |
https://treatment.plazi.org/id/03F50713-9979-FFC2-0376-FE7BF8A3F35E |
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treatment provided by |
Conny |
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scientific name |
Redunca arundinum |
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Southern Reedbuck
French: Rédunca des roseaux / German: GroRriedbock / Spanish: Redunca meridional
Other common names: Common Reedbuck
Taxonomy. Antilope arundinum Boddaert, 1785 ,
Cape Colony.
Numerous subspecies have been described; all are considered invalid here except for R. a. occidentalis , which is herein considered a separate species. Monotypic.
Distribution. DR Congo S to N Namibia and N Botswana, and S through Zimbabwe, S Mozambique (approximately S of Zambezi River), NE South Africa (including KwaZulu-Natal), and Swaziland; an isolated population is found in S Gabon. No studies have attempted to distinguish the exact geographical range of R. arundinum from that of the Zambian Reedbuck ( R. occidentalis ) where the two populations meet. View Figure
Descriptive notes. Head-body 130-160 cm (males) and 120-140 cm (females), tail 18-30 cm; shoulder height 80-150 cm (males) and 65-95 cm (females), weight 51-95 kg (males) and 39-85 kg (females). The Southern Reedbuck is significantly larger than the sympatric Southern Mountain Reedbuck ( R. fulvorufula ) in southern Africa. Males are larger than females. The dorsal pelage is uniform buff or grayish-fawn,finely grizzled with brown; the underparts are white. A vertical black stripe marks the fronts of the forelegs; similar markings are usually present on the lower hindlegs. The tail is very bushy; the upper surface is fawn like the body, while the underside and tip are white. The head and neck tend to be brighter and more yellowish-brown than the rest of the body. The face is generally unmarked, although a patch of darker brown is occasionally present on the lower face or forehead. The upperlips, underside of the jaw, and a small area on the upper throat are white; a whitish spot is also present at the inner corner of each eye and may extend into a pale ring around the eye itself. The ears are pointed; at the base of each ear is a glandular area (present in both sexes) that is usually covered with hair, but appears as a distinctive bare black circle when the subauricular glands are active. Horns are present only in males, and have a distinct concave curvature with the horn tips pointing forward. Transverse ridges occur on the basal two-thirds; the horn tips are smooth. Diverging from base to tip, the horns are the longest among the genus Redunca , growing 25—45 cm. The degree of divergence is extremely variable; tip-to-tip distances may range from 24 cm to 52 cm. A conspicuous pale crescent of swollen tissue is present at the base of each horn. Dental formula is 10/3,C0/1,P3/3,M3/3 (x2) = 32.
Habitat. Tall grass savannas and savanna-woodlands associated with year-round water supplies. Cover, provided by tall grass, is an essential refuge; most other ungulates avoid these areas, and general habitat selection is correlated with an absence of other ungulate species. Grassland habitats dominated by Trachypogon spicatus, Hyparrhenia dissoluta, or Elionurus argenteus are used extensively after the grasses have grown tall enough to provide cover (beginning in November in South Africa). During the dry season (June-October in South Africa), riverside habitats dominated by Phragmites australis and associated bush are frequently used due to the lack of sufficient food and coverin savannas. Overall population densities are generally less than 0-2 ind/km?. In protected areas, average densities of 1:4-7-6 ind/km? have been recorded, with pockets of favorable habitat supporting localized densities of 25-35 ind/km?.
Food and Feeding. Various grasses make up the bulk of the diet of the Southern Reedbuck across seasons; herbs and shoots/leaves are consumed only in very small amounts. The Southern Reedbuck avoids competition with sympatric ungulates by feeding on relatively unpalatable grasses. Principal grass species consumed in the savanna-woodland of north-eastern South Africa are Heteropogon contortus, Trachypogon spicatus, and Hyparrhenia dissoluta (the latter may compose 90-95% of the food eaten in a foraging bout). Panicum maximum is a winter staple, being one of only a few grasses consumed when dry. Themeda triandra and Urochloa mosambicensis grow only in low densities but are consumed year-round when present. In riverine habitats in the same area of South Africa (used in June—October), the principal grasses consumed are Leersia hexandra and Phragmites australis . Herbs play a larger dietary role in this dry season habitat: Cyperus spp., Commelina africana, Klingia spp., Polygonum spp., and Pycreus polystachyos are all eaten, and the leaves from the shrub Albizia harveyi may be consumed regardless of the stage of leaf development. The Southern Reedbuck is a thorough forager, covering approximately one square meter per minute while feeding. In marshy terrain, this species has been recorded wading into water to a depth of 20 cm to feed.
Breeding. The Southern Reedbuck reproduces throughout the year, but shows seasonal trends. In eastern South Africa, a peak in breeding behavior has been observed in March—-May (Natal Highlands) and May-June (Kruger National Park). The majority of births (over 50%) occur between November and January in the Natal Highlands; in Kruger National Park, this peak is between December and April. Courtship involves repeated cycles of following and pausing (the pauses including naso-anogenital contact between the trailing male and the female). A female’s urine, sampled by the male either in midstream or from the ground, is tested with the flehmen response. Ritualized foreleg kicking, or “laufschlag,” is conspicuously absent from the courtship repertoire of male Southern Reedbuck; this may serve to prevent hybridization with other Redunca species. Copulation attempts begin after 1-3 cycles of following; several additional repetitions may be required before mounting is successful. Copulation lasts approximately two seconds, and mounting attempts cease after ejaculation. The gestation period is estimated at 233 days; litter size is one. For at least six weeks after birth, the infant is hidden in dense vegetation, adopting a prone position with the body, neck, and head pressed close to the ground. During this caching period, the mother remainsin the vicinity of the infant (rarely venturing more than 200 m away), but only visits sporadically for nursing and grooming. A single visit during hours of daylight (usually midday) is normal, but if there are disturbances in the area the infant may go all day without nursing. Scent appears to be used by the female to determine the location of the infant, who will remain prone until the motheris within 1-2 m. Nursing lasts for 2-5—4-5 minutes, after which the infant caches itself in a new spot (hiding spots are not reused). Mothers are highly protective of their offspring and have been observed fending off predators such as Chacma Baboons (Papio ursinus). At three months, juveniles accompany their mothers, remaining within 15-30 m but lagging behind and then running ahead rather than following closely. Separation from adults while resting continues until after weaning (at approximately four months) and full independence occurs at 11-12 months, just prior to the birth of the next offspring. The horns of males begin to grow at 6-8 months. Young females tend to leave their natal home range earlier than males (usually before two years for females vs. 2-3 years for males); females also disperse greater distances. Maximum longevity in captivity is over 16 years.
Activity patterns. Active throughout the day and night, with peaks in activity around dawn and dusk. The hours after sunset are a principal active time of the Southern Reedbucks in KwaZulu-Natal, South Africa. In winter, temperature fluctuations appear to drive daily activities: in early morning (05:00-06:00 h), there is an uphill movement from valleys to higher hills where the sun hits first. After foraging at higher elevations for several hours,there is a gradual downward movement (with intermittent grazing), returning to sources of cover around rivers in valley bottoms. Grazing bouts are interspersed with periods of rest and rumination that may last for 2-3 hours. In tall grass habitats, Southern Reedbucks may simply lie down to rest, then rise and resume foraging; in open habitats, they will retire to cover.
Movements, Home range and Social organization. The Southern Reedbuck has a very loose social system; associations between adults appear to be a function of location rather than a true social bond. This species is usually observed singly, in pairs, or in small groups that frequently change in composition. Solitary individuals of both sexes are common; lone males are most frequently seen leading up to the breeding season (January-April), whereas females tend to be most solitary from April to July. Family groups of 2-3 animals (with at least one adult of each sex) occur from the end of the breeding season (May or June) until the beginning of summer (November); group size increases during the dry season (July-September) when populations congregate around water sources. As males become more solitary prior to the breeding season, all-female groups become common. Groups tend to be more dispersed in open grassland and stick closer together in dense cover. Individual Southern Reedbucks inhabit well-defined home ranges, the boundaries of which fluctuate seasonally (expanding slightly during the summer when vegetation is more widely available), but which remain relatively constant between years. Fidelity to the home range is only broken due to environmental events such as fire or drought. Average home range size varies from 0-22 km?® to 0-54 km?* in different parts of the species’ distribution. Home ranges of females are larger than those of males, and subadults range more widely than settled adults. The home ranges of females show significant overlap, but males differ in their degree of territoriality. Where food and cover are limited, territorial resource-defense is used to gain access to females. When the same resources are plentiful, males defend access to females themselves; in this situation, male home ranges tend to overlap and be smaller (0-05 km?®), with adjacent males forming a dominance hierarchy.
Status and Conservation. Classified as Least Concern on The IUCN Red List. Hunting and habitat loss have been the greatest threats. The Southern Reedbuck is most abundant in South Africa, with an estimated population exceeding 13,000 individuals; Kwa-Zulu-Natal holds the greatest concentration. The Zimbabwean population contains at least 3000 individuals, and there is a significant population in central Mozambique (Gorongosa National Park). Southern Reedbucks have been extirpated from Lesotho due to habitat destruction and hunting, and numbers are greatly reduced in Swaziland, where only a few fragmented populations survive in nature reserves. Populations in the north-west of the species’ distribution have been greatly reduced as a result of intense hunting for meat; the species may be extinct in the Republic of the Congo, and recent records are very rare from some areas of DR Congo and Gabon.
Bibliography. Boyes & Perrin (2006), Cotterill (2000), East (1999), Howard (1986a, 1986b), IUCN/SSC Antelope Specialist Group (2008av), Jungius (1970, 1971), Jungius & Claussen (1975), Kingdon (1982, 1997), Lydekker (1914), Walther (1990), Weigl (2005).
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