Common Duiker

Sylvicapra grimmia

General Description

Scientific Name: Sylvicapra grimmia

Subspecies: 14 subspecies

S.g.grimmia: Southern Grey Duiker
S.g.burchelli: Eastern Cape Grey Duiker
S.g.caffra: Limpopo Grey Duiker
S.g.steinhardti: Kalahari Grey Duiker
S.g.splendidula: Angolan Grey Duiker
S.g.orbicularis: East African Grey Duiker
S.g.diserti: Desert Grey Duiker
S.g.abyssincia: Nile Grey Duiker
S.g.rosevelti: Northern Grey Duiker
S.g.coronata Western Grey Duiker

Other Names: Grey Duiker or Bush Duiker

Status: Least Concern (stable/decreasing)

Population Estimate: 1.66-10 million

Population in Surveyed Areas: 125

Diet: Herbivore - Browse, Grasses & Fruits

Male Size: 12-23Kgs

Female Size: 13-25 Kgs

Trophy Size: 11.43 cm

Generation Length: 4.9 years

Reproductive Season: Year Round

Time of Activity: Diurnal

Description: It grows to about 50 cm (20 in) in height and generally weighs 12 to 25 kg (26 to 55 lb); females are generally larger and heavier than the males. Only the male has horns and these usually grow to 11 cm (4.3 in) long, though high trophy quality mature males can grow horns between 15-45 cm (6-19 inches) long in extreme cases.

Compared to other duiker species, they have longer, more slender legs, a shorter body and a longer neck, which makes it easily identifiable against other species. Despite their name, coloration varies greatly over the species expensive range, ranging from a chestnut brown in the forested areas of Angola, to a grizzled grey in savannah habitats, and a light brown in the arid portions of it's range. Another identifying feature are the vertical bands of black around it's hocks, looking much like black socks.

Ecology: Grey Duiker are possibly one of the most adaptable antelope species in sub-Saharan Africa, being able to live in a range of habitats, anything from arid semi-desert and dry grasslands, to closed forests in some instances. Their presence in an area is largely dictated by the presence of thick scrub and thorny vegetation, that they can easily dive into to escape danger at a moments notice. A diverse canopy structure and plant species composition of the lower vegetation strata are essential components of a suitable habitat. Common duiker readily inhabit the shrubby borders surrounding smallholdings and are often seen in gardens on the periphery of towns and cities. It occupies habitats at altitudes from sea level to the snow line at approximately 1,800 m. Its distribution does not overlap that of the forest duiker species.

Duikers eat a range of different vegetation, largely dependent on the habit type they occupy, eating a range of different fruits, seeds, grasses, tubers, and young shoots of different woody vegetation. They've also been documented eating insects, small reptiles and birds, and even the occasional carrion. They have a very fast metabolic rate, requiring 6,960 KJ of energy per day to survive, much higher to comparatively sized antelope.

Grey Duiker are commonly preyed upon by a number of carnivores, such as Leopards, Cheetahs, African Wild Dogs, Caracals, Servals, Jackals, Large Birds of Prey, and Pythons. Other larger predators may take them opportunistically.

Behavior: 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 but may be found walking around during midday hours on overcast and rainy days. Because ultra-violet radiation from sunlight kills many exterior body parasites, the duiker can be found standing or lying down in the early morning sun to groom its pelage and remove parasites and accumulated dirt.

Territory and home range size varies greatly, ranging from around 1.9 hectares per animal in wet areas, to 12 hectares per animal in very arid areas. In habitats where food and water is abundant, densities are usually between 1 grey duikers per 3 hectares.

Duiker are solitary animals with every individual inhabiting its own territory and home range. Males and females do not form permanent or lifetime breeding bonds, as is often believed. 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 area.

Reproduction: During the rut, a single adult ram will mate with up to three adult ewes, generally with those in territories bordering its own. Lambs are born throughout the year as mating can take place at any time. Ewes become sexually mature at 8-9 months age and socially mature (time of first mating) at 10-12 months. The first lamb is born at 15-17 months after a gestation period of 195-205 days. The lambing interval is eight months, thus a single ewe can produce three lambs every two years. Although twins do occur, they are very rare. A captive female can live up to 12 years and the overall lambing success is 97%. The ram does not take any part in the nursing or raising of the lamb. At birth the lamb weighs between 1.4 and 1.9 kg. It weighs 9 kg or half its adult mass at 4.5 months and attains its adult mass of 15-20 kg at eight months. The trophy status of 11.4 cm may be reached at 12 months old.

Grey duiker have the unique ability to self regulate their populations, based on the amount of food and water available, and their breeding success over previous years, something very unique amongst antelope. They have the ability to shrink the size of its home range to accommodate more individuals when the veld condition improves during periods of favourable rainfall. This ability, combined with an extremely successful breeding potential, allows duiker populations to grow impressively within a single year. If the veld condition deteriorates, they expand their home ranges, push out the younger animals from the latest established territories and

reduce the lambing frequency.

Whenever an individual is removed from its territory by hunting or cropping, the lamb of an adjacent family-pair soon re-occupies the territory. During the Eastern Cape valley bushveld study, 28 duiker were culled in a valley of 120 ha in the centre of a 3 500 haranch, over a period of five months. This translates to one duiker being cropped per 4.3 ha. Twelve months later the population had regained the same density. This occurred during a season with a rainfall 30% above the annual mean.

Conservation Analysis

Current & Historic range: The common duiker has one of the largest contiguous ranges of any African antelope, and the largest range of any duiker species. The only regions where they aren't present are the northern Sahara desert, the Ethiopian/Somalian desert, the tropical rainforests bordering the equator, the Namib Desert and the humid coastal thickets of central east

Africa, Mozambique and the Knysna/Tsitsikamma forests of the southern Cape. Grey Duikers are one of the few antelope species to occupy almost of their historic range, even though fragmentations and population reductions have occurred in some areas, largely due to human development.

Current & Historic Populations:. the historic population number of Grey Duiker is largely unknown, though we can assume it was higher in the past, due to much lower levels of destructive agriculture, poaching, and human development. That being said, it's estimated that least 1.66 Million of these antelope exist across their range, though this estimate may be off by a considerable margin, and may be as high as 10 million. Due to the reclusive nature of this species, it can be difficult to accurately monitor populations over large areas. Non-traditional population monitoring techniques, such as Camera Trapping or Spoor/Track counts could achieve better results.

Map of Common/Grey Duiker Range

Threats to Species Survival: Through populations of grey duikers across Africa have decreased in recent years, overall the species is still common to abundant over the majority of it's range. It's small size and secretive range means it can persist in human dominated areas for longer than other antelope species. That being said, poaching for the bush meat trade, as well as competition with domestic livestock, particularly goats, do threaten some populations. Most poached duiker are killed with snares or with packs of dogs, though bow's are often used on occasion.

Recommended Conservation Actions:

Increased protection from development and poaching in populations close to human settlements, as well as further economic incentives to not overharvest a particular species.
Greatly increased regulation in the Bush Meat industry, including a ban on the sale of blue duiker meat in many parts of their range. This should be done whilst allowing for local subsistence harvests, and regulated tourism hunting.
Increase surveying capabilities of most of it's populations, especially outside of protected areas, where much about the statusof this species is unknown.

Economic & Cultural Analysis

Ecotourism Value: Low

Hunting Value: Low-Moderate

Meat Value: Moderate

Average Trophy Value: $420 USD

Meat Yield per Animal: 6-11 kg

Economic Value/Impacts: The economic impact of grey duikers is low compared to many other species. Though their meat is palatable and flavorful, each anima is quite small and yield is low, so they aren't often pursued as a regular food source.

Grey Duiker are valuable to the Trophy Hunting industry, being a member of the Tiny 10. Though easier to harvest than smaller duiker like Blue or Red Forest Duikers, they're still a challenge to harvest, especially to get a trophy individual. That being said, they are usually one of the cheapest animals to hunt on safari, usually around $300-$450 USD per animal. They have some value from an eco-tourism perspective, though this is limited due to their reclusive nature, making them very hard to spot.

Cultural Value: Small antelope like Grey Duiker likely made up a significant portion of our ancestors diet during prehistoric times, due to their abundance, small size, and palatability. The meat of a grey duiker is held in very high regard, having fine grain and tender texture, and a mild flavor akin to lamb. Their overall value as a meat animal is limited by their small size, but their very large population, and the ability to persist in areas altered by human activity makes them an important wildlife species.

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