Bovids V: Duikers

(Cephalophinae)

Class: Mammalia

Order: Artiodactyla

Suborder: Ruminantia

Family: Bovidae

Subfamily: Cephalophinae

Thumbnail description
Timid small, tropical antelopes; females often larger than the males; coat color is usually reddish brown, but can be gray, black, or striped; most species have a tuft of hair between a pair of horns; maxillary glands used for scent marking; considered browsers; agile jumpers and hiders; reflect the primitive, ancient lifestyle of bovids

Size
Body length 22–59 in (59–145 cm); shoulder height 12–34 in (30–85 cm); 9–176 lb (6–80 kg)

Number of genera, species
2 genera; 18 species

Habitat
Dense forest, lowland or high montane forest, savanna, and open bush; closely tied to dense cover for hiding

Conservation status
Endangered: 1 species; Vulnerable: 3 species; Lower Risk/Near Threatened: 9 species; Lower Risk/Conservation Dependent: 3 species; Lower Risk/Least Concern: 2 species

Distribution
Sub-Saharan Africa

Evolution and systematics

The Cephalophinae belong to the neotragine radiation of bovids. The ancestors of these browsing antelope first appeared during the Miocene, and later invaded Africa and Asia. Although their fossil record is sparse, Cephalophinae share many similarities with early bovids.

Modern Cephalophinae include 18 species represented by two genera, Sylvicapra and Cephalophus. Sixty-five subspecies have been identified. Cephalophus can be divided into four subgenera, which can be described as the conservative dwarfs, the diverse red duiker lineage, the fiber duiker lineage, and the giant duiker species. Several researchers have argued that the conservative dwarf subgenus is, in fact, a unique genus, Philantomba.

Physical characteristics

The Cephalophinae vary considerably in size. Their body shape is consistent across species, and designed for traveling through dense vegetation. They have arched bodies, short forelegs, long hind limbs, and strong hindquarters. Females are often as much as 4% longer and may be taller than males. Cephalophinae weigh 9–176 lb (6–80 kg) and reach shoulder heights of 12–34 in (30–85 cm). Their coats are coarse and generally reddish brown, with a white underbelly. However, their coloring can range from pale gray to dark brown or black, and several species have unique coat colors and patterns. Tails may be as short as 1.5 in (4 cm) or as long as 6 in (15 cm). A hair tuft between a pair of short, ridged horns is common. Duikers have large, gash-like scent glands beneath the eye.

Distribution

Cephalophinae have a widespread distribution across sub-Saharan Africa and on the islands adjacent to these coastal regions. The areas of greatest density are in equatorial Africa within the rainforest belt that stretches from Guinea to the Democratic Republic of the Congo.

Habitat

Duikers prefer habitats of rainforest or dense bushland, although some species choose to live in swamps or mountainous regions. Urbanization has forced some populations to relocate or adapt to the local ecology. Others, more susceptible to habitat loss and ecological exploitation, have patchy distributions.

Behavior

Duikers earned their name for their tendency to flee in a series of diving jumps or to duck for cover beneath bushes and in fallen tree trunks when frightened. The name is derived from the Afrikaans word for diver. Most duiker species are nocturnal, foraging for food and surveying their territory from dusk to dawn. They remain sedentary during the daylight hours, often hidden inside hollow trees or behind fallen trunks.

In addition to being skittish, both male and female duikers are highly territorial animals. They are typically found alone, in pairs, or in pairs with one youngster, and they live in precisely defined habitats. Some species have fixed core territories with dynamic boundaries that overlap with other pairs, while others keep stricter borders. Duikers will patrol their territories alone or in pairs, and chase away any intruders. In zoos, male duikers are intolerant of other males and they fight violently if housed in the same pen. Females seem more tolerant of one another in captive settings.

Duikers mark their territorial boundaries, their mates, and their calf with olfactory cues secreted from the maxillary glands, located below the eye. Pedal glands, located within the hooves, and feces also serve as territorial scent markers. Bucks mutually mark by pressing their glands against each other prior to fighting.

Feeding ecology and diet

Cephalophinae have diverse diets and notable feeding habits, preferring the leaves, shoots, and tender branches of trees and bushes, fruits, and seeds. As much as 90% of the animal's diet may be derived from fruits and leaves, with some seasonal variation. They can often be found grazing beneath trees on the fruits and seeds dropped by monkeys. Occasionally, they will eat insects, eggs, birds, and small mammals. Cephalophinae are known to raid plantations adjacent to forests for palm nuts, mangoes, and cocoa pods.

Cephlophinae conduct most foraging between dusk and dawn. The rainy season deposits enough moisture on the leaves of bushes and trees for the animals to meet their fluid needs.

Reproductive biology

All members of the Cephalophinae subfamily are monogamous, generally producing one litter per year. Females are sexually mature at approximately nine months of age, males between 12 and 18 months. Cephalophinae are non-seasonal breeders, but in some species such as the bush duiker (Sylvicapra grimmia), calf births may peak during the summer months. Gestation among the Cephalophinae can be as short as four months or as long as nine months. Single births are the norm, but it is not unheard of for bush duikers to bear twins. Male duikers do not participate in rearing apart from delivering warnings about nearby predators and defending the trio's territory. Most calves are weaned from their mothers between five and nine months of age.

Conservation status

Due to their timid nature, it is difficult to estimate the population sizes of many species of Cephalophinae. Species with wide habitat ranges and those that are highly adaptable to changing ecological conditions are not threatened. However, 16 of 18 species have been placed on the IUCN Red List of Threatened Species. Most of those listed are Lower Risk, but C. adersi is Endangered and C. jentinki, C. spadix, and C. zebra are Vulnerable. Loss of habitat and bushmeat hunting continue to be the greatest threats to Cephalophinae.

Significance to humans

The Cephalophinae represent an essential source of protein and income throughout the forest regions of Central and West Africa. There is ample evidence that the current levels of hunting are unsustainable. In addition, the dwarf duikers are prized by trophy hunters, who seek to add full body mounts of the smaller animals to their collections.

Species accounts

Resources

Macdonald, David, ed. The Encyclopedia of Mammals. Vol. 2, Primates and Large Herbivores. New York: Facts On File, 2001.

Nowak, Ronald, M. Walker's Mammals of the World. 6th ed. Baltimore: Johns Hopkins University Press, 1999.

Walther, Fritz Rudolf. "Duikers and Dwarf Antelopes." In Grzimek's Encyclopedia of Mammals, Vol. 5, edited by Sybil P. Parker. New York: McGraw-Hill Publishing Company, 1990.

Wilson, Don E., and DeeAnn M. Reeder, eds. Mammal Species of the World: A Taxonomic and Geographic Reference. Washington, DC: Smithsonian Institution Press, 1993.

Barnes, R. F. W. "The Bushmeat Boom and Bust of West and Central Africa." Oryx 36, no. 3 (July 2002): 236–42.

Bowland, A. E., and M. R. Perrin. "Temporal and Spatial Patterns in Blue Duikers Philatomba monticola and Cephalophus natalensis." Journal of Zoology 23, no. 3 (November 1995): 487–498.

Freer, F. "Comparative Diet of Cephalophus callipygus and C. dorsalis, Sympatric bovids of the African Sempervivent Forest." Mammalia 53, no. 4 (1989): 563–620.

Hoffman, T., and H. Roth. "Feeding Preferences of Duiker (C. maxwelli, C. rufilatus, C. niger in Ivory Coast and Ghana." Mammalian Biology 68, no. 2 (2003): 65–77.

Matthee, C. A., and T. J. Robinson. "Cytochrome b Phylogeny of the Family Bovidae: Resolution Within the Alcelaphii, Antilopini, Neotragini, and Tragelaphini." Molecular Phylogenetics and Evolution 12, no. 1 (June 1999): 31–46.

Newing, H. "Bushmeat Hunting and Management: implications of Duiker Ecology and Interspecific Competition." Biodiversity and Conservation 10, no. 1 (June 2001): 99–118.

Schweers, S. "On the Reproductive Biology of the Banded Duiker Cephalophus zebra (Gray, 1838) in Comparison with Other Species of Cephalophus." Zeitschrift Für Saeugetierkunde 49, no. 1 (1984): 21–36. van Vuuren, Bettine Jansen, and Terence J. Robinson. "Retrieval of Four Adaptive Lineages in Duiker Antelope: Evidence from Mitochondrial DNA Sequences and Fluorescence in situ Hybridization." Molecular Phylogenetics and Evolution 20, no. 3 (September 2001): 409–425.

IUCN—The World Conservation Union. Rue Mauverney 28, Gland, 1196 Switzerland. Phone: +41 (22) 999 0000. Fax: +41 (22) 999 0002. E-mail: mail@hq.iucn.org Web site:

African Wildlife Foundation. "Duiker." [April 28, 2003]. .

IUCN. The IUCN Red List of Threatened Species. [April 28, 2003]. .

Jentink's duiker. [April 28, 2003]. .

[Article by: Hannah Hoag, MS]