Sylvicapra grimmia (Linnaeus, 1758)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 707-708

228.

Bush Duiker

Sylvicapra grimmia

French: Céphalophe de Grimm / German: Kronenducker / Spanish: Duiker de sabana

Other common names: Common Duiker, Gray Duiker, Grimm's Duiker

Taxonomy. Capra grimmia Linnaeus, 1758 ,

Cape Colony.

There is considerable geographic variation in this wide-ranging species, and overforty subspecies have been described. Many of these are considered not well founded, butthis speciesis in need of taxonomic revision. Intermediate variations are often seen where the ranges of two subspecies meet. Eleven subspecies are recognized here; a twelfth subspecies (currently undescribed) may inhabit the higher elevations of Mount Kilimanjaro, Tanzania.

Subspecies and Distribution.

S. g. grimmia Linnaeus, 1758 — S South Africa (Cape Province).

S. g. altwallis Heller, 1912 — C Kenya (Aberdare Mts and Mt Kenya).

S. g.caffra Fitzinger, 1869 — S Mozambique, E Zimbabwe, Swaziland, Lesotho, NE South Africa.

S. g. campbelliae Gray, 1843 — E Guinea, S Mali, N Ivory Coast, S Burkina Faso, N Ghana, Togo, Benin, S Niger , Nigeria, N Cameroon, S Chad, Central African Republic, SW Sudan, W Uganda, Rwanda, Burundi.

S. g. hindei Wroughton, 1910 — SE Kenya and N Tanzania.

S. g. lobeliarum Lönnberg, 1919 — E Uganda, W Kenya (restricted to Mt Elgon).

S. g. madoqua Ruppell, 1835 — W Ethiopia (highlands), W Eritrea.

S. g nyansae Neumann, 1905 — SE Sudan, W Ethiopia, E Uganda, and W Kenya.

S. g. orbicularis Peters, 1852 — S Somalia, E Kenya, Tanzania, E Zambia, Malawi, N Mozambique.

S. g. splendidula Gray, 1871 — SE Gabon, S Republic of the Congo, S DR Congo, N Angola, E Botswana, W Zambia, W Zimbabwe.

S. g. steinhardti Zukowsky, 1924 — S Angola, Namibia, W Botswana, NW South Africa.

Descriptive notes. Head-body 70-105 cm (males) and 90-115 cm (females), tail 10-20 cm, shoulder height 39-68 cm; weight 9.7-22. 4 kg (males) and 10.3-26. 3 kg (females). Weights vary regionally; animals from the northern parts of the species’ distribution (including West Africa) tend to be smaller than those from the south. Females are typically 2-4 kg heavier than males. In form, the Bush Duiker generally resembles other savanna-dwelling small antelopes more than other duikers: the back is relatively straight (not arched), the legs are long and slender, the neck is longer, and the head is often held above the line of the back. Pelage characteristics vary widely between locations. Coat length is longest in montane forms from East Africa (notably in the subspecies altivallis and lobeliarum), but is often short and glossy in lowland forms. Overall color is grayish-yellow or sandy brown, but may be very red or pale. Each hair is banded, creating a speckled or grizzled appearance. The underparts and inside of legs are white or pale gray. The legs are generally colored as the body, with a black patch above the hooves and a variable dark stripe on the front of the forelegs. A similar stripe is present on the hindlegs in some specimens. The tail has a variable extent of black on the upper surface (ranging from totally black to just the tip); the underside of the tail is bushy and white. The head is generally more rufous than the body, especially the forehead. The rhinarium is black, and the underside of the jaw is whitish. A black or dark brown blaze runs up the bridge of the nose from the muzzle and is highly variable in length. In some individuals it fades away below the eyes (typical of the subspecies orbicularis, splendidula, and steinhardti), whereas in others it continues clearly to the top of the head (usually seen in subspecies altivallis, campbelliae, and hinder). A whitish ring may be present around the eyes (especially in subspecies orbicularis). The slit-like openings of the preorbital glands are large and conspicuous. The ears are large and pointed; the outer surfaces are gray, the inner surfaces fringed with white hair. The size of the ears appears closely linked to climate and habitat: they are largest in hot, arid regions. The coronal tuft is generally long, narrow, and wispy; its color varies from rufous to black. Horns are generally present in males only; they are slender,straight, and pointed, rising almost vertically from the forehead. Average horn length is 9-9 cm (typical range 7.5-12. 5 cm); horns up to 18 cm long have been recorded. Short, stunted horns are occasionally seen in females; nearly 13% of subspecies steinhardti females in eastern Botswana are horned. Dental formulais10/3,C0/1, P3/3,M3/3(x2)=232

Habitat. A wide range of mixed woodland and savanna habitat types are used. Bush Duikers may be found from sea level to over 4300 m on Mount Kenya (where the species may be found at the snow line). Cover (shrubbery, thickets, or woodland) is needed for shelter; short open grasslands and woodlands without underbrush are avoided. Rainforests and deserts are also avoided, although forest edges may be used for shelter. Bush Duikers are found in a diverse array of woodlands, including those dominated by Brachystegia—fulbernardia (miombo), Colophospermum mopane and Isoberlinia (mopane), Terminalia, or Acacia. Population densities in Zimbabwe average 1-9-9 ind/km?, and are highest in Baikiaea woodland. Typical population density across the species’ range is 2-3 ind/km*. Bush Duikers frequent seasonally burned savannas; the flush of new growth 1-2 months after the burn may cause duiker population densities to double. Baboons (Papio sp.) will occasionally prey on young duikers; other predators include Leopards (Panthera pardus), Servals (Leptailurus serval), African Wild Dogs (Lycaon pictus), martial eagles (Polemaetus bellicosus), and African rock pythons (Python sebae). If pressed, Bush Duikers will readily take to water; they are strong swimmers and may swim for more than 1 km. They are able to jump over 1-8 m, but usually run beneath obstacles when avoiding predators.

Food and Feeding. A browser. Small, ground-level herbs constitute the main part of the diet, accounting for 65% of feeding time. Leaves, stems, and sometimes the roots of such herbs are all eaten. Fallen, often partially dry leaves and fruits are also consumed. Grass is eaten only very rarely, and then only as very young shoots. Stomach content analysis in eastern Zambia revealed a preference for the leaves of Bauhinia petersiana, Brachystegia spp., Combretum molle, Diospyros kirkii, Julbernardia sp., Securidaca longipedunculata, Strychnos sp., Syzygium sp., Tricalysis sp., and Xeromphis obovata. Fruits from Brachystegia spp., Dichrostachys cinerea, Gardenia subacaulis, Julbernardia sp., Pseudolachnostylis maprouneifolia, Ximenia caffra, and Ziziphus abyssinica are preferentially eaten, as are the flowers from Brachystegia spp., Dolichos spp. or Vigna sp., Julbernardia sp., and Protea angolensis . Observations of foraging Bush Duikers in Zimbabwe revealed a very high preference for leaves of Albizzia amara, Commelina welwitschii and C. bengalensis, Grewia flavescens, Pterocarpus angolensis , and Securinega virosa, and the fruits of Acacia robusta, Flacourtia indica, Grewiaflavescens, and Ziziphus mucronata. Resin from Acacia trees may be chewed or licked from tree trunks. Animal matter is occasionally eaten, including termites, eggs, reptiles, and birds; there are several records of Bush Duikers actively hunting and killing ground-dwelling birds. This species is generally independent of free water, but tends to drink daily ifit is available. In the Kalahari Desert, this species feeds on moisture-rich melons (Citrullus lanatus), berries, and tubers that are dug up using the hooves. Hanging fruits may be reached by standing upright on the hindlegs.

Breeding. Reproduction occurs throughout the year across most of the species’ distribution. There is a peak in births during the rainy season (November-March) in southwestern Zimbabwe. Estrus lasts 1-5-3 days, but is difficult to detect. Courtship behavior involves frequent chases of the female by the male. Males frequently vocalize with a low-pitched bleat during courtship; females may bleat while running away during preliminary chases. Pursuing males will frequently lick or bite at the hindquarters of the female. As estrus peaks, the female slows her pace and will urinate, allowing the male to perform flehming to determine receptivity. “Laufschlag” (a ritualized foreleg kick) precedes copulation, which is very short (2-5 seconds). Gestation is approximately 200 days (a range of 186-216 days has been accurately recorded in captivity). Births typically occur in early morning, and occasionally in the late afternoon or evening. Litter size is one; weight at birth is approximately 1-7 kg. Infants are darker in color and have woollier coats than adults; they are precocial, but are cached for several days. The initial hiding spotis typically less than 100 m from the birth site. The mother will return to the infant 4-6 times during the day to nurse (such behavior at night has not been studied). Infants begin testing solid food at two weeks. Weaning occurs at three months, although older animals up to 4-5 months may attempt to suckle; the association between mother and infant does not last past six months. There is a postpartum estrus. The average interbirth interval in captive Bush Duikers is 234-259 days. Females experience their first estrus between eight and twelve months of age; males become sexually interested at approximately 16 months. Maximum longevity in captivity is 14-15 years.

Activity patterns. Diurnal, trending towards crespuscular. Activity commences at 05:00 h or slightly thereafter and continues until around 08:00 h, when resting places are returned to. Active foraging commences again in the late afternoon, typically at 16:30-17:30 h, and may continue well into the evening. Night-time resting places in dense cover or against boulders are typically retired to by 23:30 h. Foraging accounts for 7-8 hours of the day, split between morning and evening. Midday activity is most frequent on cool or cloudy days, or during light rain. Activity levels during the day tend to be higher in more open habitats where visibility, and therefore the ability to detect predators, is greater.

Movements, Home range and Social organization. Primarily solitary. Associations between males and females only occur during estrus, and may last for several days. Observed groups of three are usually an adult male accompanying an estrous female and her most recent offspring. Males and females occupy individual home ranges. Ranges of females may overlap with those of other females as well as males, but males appear to exclude other males from their home ranges. Preorbital gland secretions are used by males to mark their territories; the boundaries are defended through combat. Dung middens are not used, although areas with relatively high fecal density often occur around fruiting trees (a function of increased time spent in the area). Home ranges typically have areas of dense vegetation at their core, containing several resting places that are frequently used. There is little variation in home range size between the sexes. In South Africa, territories are 0-21-0-27 km?; in Zimbabwe, the territories of males average 0-14 km? and female home ranges 0-13 km?. When two duikers meet, such as when both are foraging around fruiting trees, they may mutually groom each other and remain together for up to several hours before parting. Bush Duikers may associate with baboons (Papiosp.), foraging on leaves and fruit dropped from the treetops by the primates.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Bush Duiker is one of the most common and widespread African antelopes. The total population has been estimated at 1,660,000 animals, although it has been suggested that the actual number could be twice this figure. The population trend appearsto be stable, in part due to this species’ ability to colonize a wide variety of habitat types and its relative resiliency to hunting.

Bibliography. Grubb & Groves (2001), Happold (1987), IUCN/SSC Antelope Specialist Group (2008ba), Kingdon (1982), Weigl (2005), Wilson (2001).

Figures

228. Bush Duiker (Sylvicapra grimmia), 228. Bush Duiker (Sylvicapra grimmia), 229. Sahel Duiker (Sylvicapra pallidior), 229. Sahel Duiker (Sylvicapra pallidior), 230. Crowned Duiker (Sylvicapra coronata), 230. Crowned Duiker (Sylvicapra coronata), 231. Maxwell's Duiker (Philantomba maxwell), 231. Maxwell's Duiker (Philantomba maxwell), 232. Verheyen’s Duiker (Philantomba walteri)

Subspecies and Distribution. S. g. grimmia Linnaeus, 1758 — S South Africa (Cape Province). S. g. altwallis Heller, 1912 — C Kenya (Aberdare Mts and Mt Kenya ). S. g.caffra Fitzinger, 1869 — S Mozambique , E Zimbabwe , Swaziland , Lesotho , NE South Africa . S. g. campbelliae Gray, 1843 — E Guinea , S Mali , N Ivory Coast , S Burkina Faso , N Ghana , Togo , Benin , S Niger , Nigeria , N Cameroon , S Chad , Central African Republic , SW Sudan , W Uganda , Rwanda , Burundi . S. g. hindei Wroughton, 1910 — SE Kenya and N Tanzania . S. g. lobeliarum Lönnberg, 1919 — E Uganda , W Kenya (restricted to Mt Elgon). S. g. madoqua Ruppell, 1835 — W Ethiopia (highlands), W Eritrea . S. g nyansae Neumann, 1905 — SE Sudan , W Ethiopia , E Uganda , and W Kenya . S. g. orbicularis Peters, 1852 — S Somalia , E Kenya , Tanzania , E Zambia , Malawi , N Mozambique . S. g. splendidula Gray, 1871 — SE Gabon , S Republic of the Congo , S DR Congo , N Angola , E Botswana , W Zambia , W Zimbabwe . S. g. steinhardti Zukowsky, 1924 — S Angola , Namibia , W Botswana , NW South Africa .