| Bay duiker | |
|---|---|
 | |
| Individual in Gabon | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Genus: | Cephalophus |
| Species: | C. dorsalis |
| Binomial name | |
| Cephalophus dorsalis J. E. Gray, 1846 | |
| Subspecies | |
| |
Thebay duiker (Cephalophus dorsalis), also known as theblack-striped duiker and theblack-backed duiker, is a forest-dwellingduiker native to western and southern Africa. It was firstdescribed by British zoologistJohn Edward Gray in 1846. Twosubspecies are identified. The bay duiker is reddish-brown and has a moderate size. Both sexes reach 44–49 cm (17–19 in) at the shoulder. The sexes do not vary considerably in their weights, either; the typical weight range for this duiker is 18–23 kg (40–51 lb). Both sexes have a pair of spikyhorns, measuring 5–8 cm (2.0–3.1 in). A notable feature of this duiker is the well-pronounced solid stripe of black extending from the back of the head to the tail.
The bay duiker is anocturnal animal. It tends to remain solitary, but pairs can also be observed. Theleopard is the main predator of this duiker. It mainly prefers fruits, but may also feed on animal matter such as bird eggs. Females may conceive by the age of 18 months. Breeding occurs throughout the year. Gestation lasts about 240 days, following which generally a single offspring is born. The lifespan of the bay duiker is typically 17 to 18 years.
The bay duiker prefersold-growth or primary forests. It has been historicallyoverhunted across its range forbushmeat. The survival of the bay duiker is also threatened by human settlement andagricultural expansion due to this duiker's preference for old-growth forests, and habitat degradation. The bay duiker is, however, still a common duiker species, and is classified asnear threatened by the International Union for Conservation of Nature and Natural Resources.
| Phylogenetic relationships of the bay duiker (Johnston et.al. 2012) |
The bay duiker was firstdescribed by British zoologistJohn Edward Gray in 1846.[3] Thegeneric name probably comes from the combination of theNew Latin wordcephal, meaning head, and theGreek wordlophos, meaning crest.[4] Thespecific namedorsalis is aLatin word referring to the back surface of an object.[5] The common name "duiker" comes from theAfrikaans wordduik, orDutchdūken (both mean "diver")[6] owing to the tendency of this antelope to seek cover in bushes.[7] The bay duiker is also known as the black-striped duiker and the black-backed duiker.[8]
A 2001phylogenetic study dividedCephalophus into three distinct lineages: the giant duikers, east African red duikers and west African red duikers. The bay duiker was classified as a giant duiker along with theyellow-backed duiker (C. silvicultor),Abbott's duiker (C. spadix), andJentink's duiker (C. jentinki).[9] In 2012, Anne R. Johnston (of theUniversity of Orleans) and colleagues constructed a cladogram of thesubfamily Cephalophinae (duiker) based onmitochondrial analysis. They showed that within the "giant duiker" group, the bay duiker formed a clade with Jentink's duiker, and thezebra duiker is sister to this clade. Similarly, Abbott's duiker and the yellow-backed duiker form a clade sister toSylvicapra. The bay duiker and Jentink's duiker probably evolved during thePleistocene, less than 2.5 million years ago.[10]
Although the species may bemonotypic, a 2003 paper identified twosubspecies of the bay duiker:[11][12]
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The bay duiker is a moderately sizedantelope; the typical head-and-body length is 76–103 centimetres (30–41 in).[8] Both sexes reach 44–49 centimetres (17–19 in) at the shoulder. The sexes do not vary considerably in their weights either; the typical weight range for this duiker is 18–23 kilograms (40–51 lb).[13] Hence,sexual dimorphism in this species is not as remarkable as in other bovids, though females are often larger than males.[8] The tail, black on the outside but white in the inner parts, is 9–11 centimetres (3.5–4.3 in) long.[13] The tail of the eastern bay duiker terminates in a white tuft.[8] Both sexes possess a pair of spikyhorns, measuring 5–8 centimetres (2.0–3.1 in).Rowland Ward, however, recorded a maximum horn length of 12.3 centimetres (4.8 in) fromYokadouma (Cameroon).[13] The horns of females are generally narrower.[8]
Both sexes have a bright reddish-browncoat. Theventral parts and the flanks are all reddish-brown, and the legs dark brown. A notable feature of this duiker is the well-pronounced solid stripe of black extending from the back of the head to the tail. This stripe is narrower in females.[8] Due to itsnocturnal nature, the bay duiker has large conspicuous eyes. Whiskers can be observed above the eyes and around the nostrils. The patches of white fur around the whiskers are in sharp contrast to the dark reddish face.[13] Juveniles have a dark coat, that develops the stripes and chestnut to reddish-brown color gradually. The face is marked by a dark region from the nose to the forehead, separated from the rest of the face by two light brown furrows extending above or circling its eyes. Above the eyes and on the lips and chin white spots can be seen. The head has a diminutive crest (a tuft of hair), and is dark brown.[8] The eastern bay duiker is larger and heavier than the western bay duiker, with larger ears and darker coloration. The dorsal stripe is wider and lighter in color in the eastern bay duiker.[8]
The bay duiker is similar to several other duikers. Thered duiker can not be readily distinguished from the bay duiker. ThoughOgilby's duiker resembles the bay duiker in size and pelage color, the ventral side is paler and the dorsal stripe starts from the shoulders instead of the back of the head.[8] Additionally, the body posture and horn characteristics of the two species differ to a large extent.[14] The bay duiker, as well as the Ogilby's duiker, are remarkably similar to theblack duiker, except for the pelage coloration.[15] The dorsal stripe ofPeters's duiker also begins at the shoulders but widens to cover the whole of therump, as does the fainter stripe on thewhite-bellied duiker. The bay duiker can be easily told apart from theblack-fronted duiker andWeyns's duiker, that lack stripes.[8]
The bay duiker is a nocturnal animal, and consequently little is known of its behavioral patterns. During the day, the bay duiker rests against trees or in thickets. It tends to remain solitary, but pairs can also be observed. The bay duiker exhibits remarkable alertness. It depends heavily on its sense of smell for foraging and detecting potential danger. Individuals communicate throughpreorbital gland secretions and excrement. Theleopard is the main predator of this duiker.[8][13]Eagles,[7]bonobos andmandrills[16] may also prey on the bay duiker. An alarmed individual becomes motionless, and might leap to flee.[8]
The bay duiker mainly prefers fruits. It feeds on the large fruits ofIrvingia species (wild mango),Detarium macrocarpum and the spherical fruits ofMammea africana. Other fruits the duiker may eat are those ofRicinodendron heudelotii andoil-palms, the orange ones ofChrysophyllum beguei, the olive-like ones ofPseudospondias longifolia, the green plums ofPanda oleosa and those ofCola rostrata, that resemblecocoa pods. The bay duiker extracts the pulp from the seeds, making a grating sound. If the seeds are large, the duiker spits them out. Smaller seeds such as those ofAntrocaryon species may be ingested.[13] A 1989 study found that the soft seeds of plants such asDrypetes gossweileri,Staudtia gabonensis,Dacryoides buettneri,Ongokea gore,Santiria trimera,Annonidium mannii andPentaclethra macrophylla are preferred.[17] There have been reports of the bay duiker preying on birds (without feeding on the legs and wings) and theembryo of unhatched eggs,carrion, remains ofAfrican porcupines andkusimanses, termites, beetles and ants.[7][13]Dog food may serve assupplement for captive individuals.[18]
Females may conceive by the age of eighteen months. Breeding occurs throughout the year, and no clear peaks are known.[13] A study inGabon recorded birth peaks before or during maximum abundance of fruits.[19] In central Africa, births peak in January and February.[8]Oestrus lasts for just eighteen hours.[13] Therutting male pursues a female in oestrus continuously. The male might be humming and may move its foreleg outward. If receptive, the female will allow the male to mount by shifting her tail to a side.[13]
Gestation lasts for about 240 days, following which generally a single offspring is born. The infant weighs nearly 1,600–1,690 grams (56–60 oz), and its coat is dark reddish-brown. The brighter reddish-brown to chestnut color develops by five to six months. For the first few weeks after its birth, the infant is kept concealed in dense vegetation when the mother is away. The offspring can start taking solid food within a few weeks. Weaning occurs at around three-and-a-half months. The lifespan of the bay duiker averages 17 to 18 years.[8][13]
The bay duiker prefersold-growth or primary forests.[14]Home ranges of females are around 0.2–0.4 square kilometres (0.077–0.154 sq mi) large, and those of males are twice the size of those of females.[8] This duiker formerly occurred in the lowland forested areas (warm, moist rainforests) ofGuinea. Nowadays, the bay duiker can be found in moist forested islands and riparian forests in thesavannas of Guinea and northeasternSudan.[14] The bay duiker is native to several countries in western and southern Africa:Angola, Cameroon,Central African Republic,The Democratic Republic of the Congo,Côte d'Ivoire,Equatorial Guinea, Gabon,Ghana,Guinea,Guinea-Bissau,Liberia,Nigeria,Sierra Leone andTogo. It is feared to beextinct inUganda.[1]
The bay duiker has been historicallyoverhunted across its range forbushmeat. A 2007 study of the extinction of the bay duiker in theIpassa Makokou Biosphere Reserve (Gabon) held overhunting responsible for the elimination of the species from the reserve.[20] The survival of the bay duiker is also threatened by human settlement and agricultural expansion due to this duiker's preference for old-growth forests, and habitat degradation.[1][14]
The habitat of the bay duiker has depleted to a large extent due to deforestation.[14] The bay duiker, unlike the other duiker species, is still found in significant numbers,[14] and is classified asNear Threatened by the International Union for Conservation of Nature and Natural Resources (IUCN).[1] TheConvention on International Trade in Endangered Species (CITES) enlists the species inAppendix II.[3] In 1999, Rod East of the IUCN SSC Antelope Specialist Group estimated the total population at 725,000.[1] The most significant population occurs only in theTaï National Park (Côte d'Ivoire).[14] Protected areas where bay duikers occur include:Sapo National Park (Liberia);Kakum National Park (Ghana);Campo Ma'an National Park,Dja Faunal Reserve andLobéké National Park (Cameroon);Dzanga-Sangha Special Reserve andBangassou (Central African Republic);Monte Alén National Park (Equatorial Guinea);Lopé National Park andMinkébé National Park (Gabon);Odzala National Park andNouabalé-Ndoki National Park (Congo-Brazzaville);Ituri Rainforest,Kahuzi-Biéga,Maiko andSalonga National Parks (Congo-Kinshasa).[1]
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Data related toCephalophus dorsalis at Wikispecies
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