Blue duiker (Philantomba monticola)
|Size||Head-body length: 55 - 90 cm (2)|
Tail length: 7 - 13 cm (2)
Shoulder height: 32 - 41 cm (2)
|Weight||3.5 - 9 kg (2)|
Classified as Least Concern (LC) on the IUCN Red List (1) and listed on Appendix II of CITES (3).
The blue duiker is the smallest and one of the most abundant and widespread of all duiker species (4) (5) (6). Like other duikers, this diminutive antelope has a distinctive stocky body, large hindquarters, arched back and short, slender legs, a body shape adapted for easy movement through dense undergrowth (4) (7) (8). The name “duiker” comes from an Afrikaans word meaning “diver”, these species being named for their habit of diving into cover when disturbed (7) (9); in the blue duiker this behaviour is often accompanied by a loud, sneezing whistle given by the male (2) (5) (6). Coat colour is quite variable, depending on location (2) (4) (5) (6), and ranges from slate grey to dark brown, sometimes with a bluish sheen on the back, which gives the blue duiker its common name (4) (6) (10). The underparts are whitish (4) (6), as is the underside of the tail, where slightly crinkled white hairs reflect light so well that on the dark forest floor the constantly flickering tail can resemble a light flashing on and off (2) (5) (6).
Blue duikers have large eyes, fairly small ears and a wide, flexible mouth adapted to feeding on fruit (2) (4). Sexes are similar in appearance (7) and both possess short, spiky horns, though these are sometimes absent in the female or hidden by a short crest of hair (4) (10) (11). Females may also be slightly larger than males (4) (11). All duikers have a good sense of smell (5) and possess large, obvious, slit-like pre-orbital glands in front of the eyes, used in scent-marking (4) (6) (7) (11).
Blue duikers are widely but patchily distributed throughout central, eastern and southern Africa, from Nigeria east to Kenya and south to Angola, Zambia, Malawi, Zimbabwe and parts of central Mozambique, as well as on the islands of Zanzibar, Pemba and Mafia, and on the island of Bioko. They are also found in parts of South Africa, though there appears to be a break in the species’ distribution between its South African range and populations in Zimbabwe and Mozambique (1) (2) (6) (7) (12).
The blue duiker inhabits a wide range of forest and wooded habitats, including lowland rainforest, gallery forest, coastal scrub farmland, dense thicket and montane forest up to elevations of 3,000 metres. It is found in both primary and secondary forest and can also survive in small patches of modified or degraded forest and thicket, including close to human settlements (1) (2) (4) (6).
Blue duikers are most active at dawn and dusk (5) (6) (11) (13) and feed mainly on fruit, as well as leaves, flowers, fungi, seeds and sometimes insects or even small animals (4) (5) (6) (9). Like other duikers, they may follow feeding monkeys and birds through the forest, picking up the fruits that are dropped (2) (6) (7).
The blue duiker is monogamous, with pairs appearing to mate for life and living in a small territory, which is defended against other blue duikers and regularly scent-marked (2) (5) (6) (7). Breeding occurs year-round (4) (11), with a single young being born after a gestation of between 196 and 216 days (5) (6) (14). Young are able to run within half an hour of being born, though usually remain hidden in the undergrowth for the first few weeks of life (5) (7). Blue duikers become mature at around a year old, after which they are driven from the parental territory (7) (11), and are reported to live for up to ten years (2) (10).
The blue duiker is heavily hunted throughout its range and is one of the most important components of the bushmeat trade in many areas (1) (15) (16). Duiker species are particularly popular with hunters, as they are easy to catch, easy to transport and have enough meat to be highly profitable (17). However, the blue duiker appears able to withstand hunting pressure better than most of the larger duiker species and currently remains widespread and abundant (1) (2) (16).
Other potential threats include habitat destruction through the felling of forests for fuel, building materials, agriculture and the spread of human settlement (11). The felling of fruit trees and killing of monkey species in particular may further degrade blue duiker habitat and food supply (2). Although the blue duiker is again better able to tolerate this threat than other duiker species, and indeed often survives in a range of human-modified habitats, the combination of hunting and habitat loss may threaten populations in some areas, leading to local declines (1).
This resilient species still occurs in large and generally stable numbers in most areas and is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning international trade in blue duikers should be carefully monitored and controlled (1) (3). The blue duiker should continue to survive in large numbers for the foreseeable future, provided human population densities remain low to moderate over large parts of its range. Although protected areas make up only a small part of its total range, its core populations are generally stable other than in areas where hunting pressures are particularly high (1).
For more information on the bushmeat trade, its problems and its solutions, see:
Bushmeat Crisis Task Force:
- Bushmeat: the meat derived from wildlife of African forests, or ‘bush’.
- Gestation: the state of being pregnant; the period from conception to birth.
- Monogamous: having only one mate during a breeding season, or throughout the breeding life of a pair.
- Montane forest: forest occurring in the montane zone, a zone of cool upland slopes below the tree line dominated by large evergreen trees.
- Primary forest: forest that has remained undisturbed for a long time and has reached a mature condition.
- Secondary forest: forest that has re-grown after a major disturbance, such as fire, farming or timber harvest, but has not yet reached the mature state of primary forest.
- Territory: an area occupied and defended by an animal, a pair of animals or a colony.
IUCN (December, 2008)
- Kingdon, J. (1997) The Kingdon Field Guide to African Mammals. Academic Press, London.
CITES (December, 2008)
- Alden, P.C., Estes, R.D., Schlitter, D. and McBride, B. (1996) Collins Guide to African Wildlife. HarperCollins Publishers, London.
- Kingdon, J. (1988) East African Mammals: An Atlas of Evolution in Africa. Volume 3, Part C: Bovids. University of Chicago Press, Chicago.
- Wilson, V.J. (2005) Duikers of Africa: Masters of the African Forest Floor. Zimbi Books, Pretoria, South Africa.
- Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
- Estes, R.D. (1992) The Behavior Guide To African Mammals: Including Hoofed Mammals, Carnivores, Primates. University of California Press, Berkeley, CA.
- Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
Ultimate Ungulate (December, 2008)
- Mills, M.G.L. and Hes, L. (1997) The Complete Book of Southern African Mammals. Struik, Cape Town.
Bioko Biodiversity Protection Program: Duikers (October, 2009)
- Bowland, A.E. and Perrin, M.R. (1995) Temporal and spatial patterns in blue duikers Philatomba monticola and red duikers Cephalophus natalensis. Journal of Zoology, 237(3): 487 - 498.
- Boehner, J., Volger, K. and Hendrichs, H. (1984) Breeding dates of blue duikers (Cephalophus monticola). Z. Saeugetierkunde, 49(5): 306 - 314.
- East, R. (1990) Antelopes: Global Survey and Regional Action Plans: West and Central Africa. Antelope Specialist Group, IUCN, Gland.
- East, R. (1998) African Antelope Database 1998. Antelope Specialist Group, IUCN, Gland.
- Eves, H.E. and Stein, J.T. (2002) BCTF Fact Sheet: Duikers and the African Bushmeat Trade. Bushmeat Crisis Task Force, Washington, DC.