Common Duiker (Grey/Bush/Grimm’s Duiker)

Sylvicapra grimmia (Linnaeus, 1758)

Photo: Deon Furstenburg

IUCN Conservation Status:

Lower Risk, least concerned (LR/lc)
“Common” is a most suitable description of this little antelope as it has the widest distribution of any African antelope. It is also known as the grey duiker, bush duiker, Grimm’s duiker or savannah duiker. The name grey duiker comes from its characteristic greyish colouring while the name “bush“ is a misconception as the animal does not live in thickets or forest but rather in savannah woodland, grassland and karroid shrubland.

In 1686, the German scientist Dr. Hermann Nicolas Grimm first described the common duiker as Capra sylvestra africana after wood (silva) and a female goat (capra). In 1758, Linnaeus named it Capra grimmia in honour of Dr. Grimm, Capra being the genus of the domesticated goat. The popular name “duiker” is derived from the Dutch “dike-er” for dive, as the animal dives for cover when alarmed.

Taxonomy

Classification

The duiker is endemic to the African continent and is divided into the forest or thicket duiker of the genus Cephalophus with 15 species, Philantomba with two species and the savannah-woodland or bush duiker, genus Sylvicapra with one species S. grimmia and 25 sub-species. Some authors recognise up to 40 sub-species.

The major sub-species are:

• the southern common duiker Sylvicapra grimmia grimmia of the Cape
• the eastern Cape common duiker S.g. burchelli of the Eastern cape and KwaZulu-Natal
• the Limpopo common duiker S.g. caffra of Zimbabwe, eastern Botswana, southern Mosambique and the former Transvaal
• the Kalahari common duiker S.g. steinhardti of the northern Cape, western Botswana and Namibia
• the Angolan bush duiker S.g. splendidula of Angola, Democratic Republic of the Congo and Zaqmbia
• the east African bush duiker S.g. orbicularis of northern Mosambique and Tanzania
• the desert bush duiker S.g. diserti of Kenya, Somalia and southern Ethiopia
• the Nile bush duiker S.g. abyssincia from Uganda to Eritrea
• the northern bush duiker S.g. rosevelti between the Nile and the Niger
• the western bush duiker S.g. coronata of West Africa.

Description

A small hunch-backed, slender-legged, short-tailed and smooth-skinned antelope varying in size between the sub-species. The Cape common duiker is the largest at 21 kg, the Angolan sub-species weighs 13 kg and the western sub-species 12 kg. The ewe is slightly larger than the ram. The coat colour varies markedly from pale yellow-grey in the lowveld, to red-brown in northern Zululand and the Eastern Cape valley bushveld, red-brown with an orange-yellow tint in the Sahel and a bright tawny with minimal speckling in central east Africa. The hair is soft and thick and generally 16 mm long, although in Botswana it grows as long as 30 mm. This gives the coat a furry appearance. Most distinctive are the dark brown facial blaze, the dark brown pre-orbital scent glands in front of each eye and the crowned tuft between the horns.

Comparison To Man

Trophy

Unlike most duiker species, where both sexes bear horns, only the male common duiker bears well developed, straight horns that are heavily grooved for 30% of the length. The horn ends are extremely sharp and smooth. Trophy status of 11.4 cm (4.5 inch) may be reached at 12 months. Rudimentary and deformed horns up to 3.5 cm long occur with 18% of the females.

Habitat requirement

Duiker are found in almost any habitat providing there is suitable cover for protection against the hot sun, humans and predators such as leopard, caracal, jackal, pythons, large raptors and feral dogs. Suitable cover are shrub-like bushes and patches of tall grass. They are only found in grassland if suitable dietary dicot forbs and/or scattered woody shrubs are available as forage. In savannah they are more likely to inhabit the ecotones surrounding bush clumps. Forest-like vegetation and plantations with a closed canopy are avoided. A diverse canopy structure and plant species composition of the lower vegetation strata are essential.

Distribution

Feeding & Nutrition

Duiker are equally active during the day and night. They feed predominantly during dusk and dawn in the cooler day hours and up to 3 hours after sunset. They usually spend the hot midday hours resting under the cover of thick vegetation. Duiker has one of the highest metabolic rates and through-flow rates of African antelope. Their daily energy requirements are 6 960 kilo-joule per day at a fermentation rate of 370 milli-mole gas per gram forage per hour, compared to 175 mmol/g/hr for kudu. On average, they consume 348 gram dried mass forage material or 1.4 kg fresh material per day. This is achieved by browsing the top four centimetres of young, actively growing shoots and twigs. It is a highly selective, concentrate feeder that predominantly browse. The diet also consists of berries, fruit, insects, small reptiles and birds, young grass leaves and mushrooms. Nibbling on fresh animal carcasses has also been recorded. Bulbs and nutritious plant roots are frequently dug up. Duiker are independent of surface water and are rarely attracted to drinking points, their daily water needs being fulfilled mainly by the moisture content of their dietary intake.

Social structure

Duiker are solitary animals with both the ram and ewe having own permanent individual territories and home ranges that are heavily defended. Males and females do not form permanent or lifetime breeding bonds. A single ram’s home range borders the home ranges of 2-3 adjacent ewes; these are only entered sporadically in order to determine the oestrus status of the female. If in oestrus, the union lasts for 2-4 days, after which the ram returns to its own territory. If not in oestrus, she will fight aggressively and force him to leave. The ewe and her lamb form a family unit that lasts until shortly before the next birth when the sub-adult leaves its mother to establish its own territory and home range. Many of these temporarily nomadic sub-adults fall prey to large predators and others are run over while crossing roads.

Disease

In some areas, especially during prolonged high rainfall, the species-specific, blood-sucking louse Linognathus breviceps can heavily infect the common duiker. The lice form a crust on the skin that causes the hair to fall out. At a low infection rate, the animal is not negatively affected but a heavy infection can cause a loss of body condition. Mortalities may occur If this loss of condition is combined with a severe cold spell. The common duiker is not susceptible to hartwater but can be infected by mange and rabies.

Information Table

Bibliography