| Blue duiker | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Genus: | Philantomba |
| Species: | P. monticola |
| Binomial name | |
| Philantomba monticola (Thunberg, 1789) | |
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| Distribution map of Blue duiker | |
| Synonyms | |
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Theblue duiker (Philantomba monticola) is a smallantelope found incentral,southern andeasternAfrica. It is the smallestspecies ofduiker. Thespecies was firstdescribed by Swedish naturalistCarl Peter Thunberg in 1789. 12subspecies are identified. The blue duiker reaches 32–41 centimetres (13–16 in) at the shoulder and weighs 3.5–9 kilograms (7.7–19.8 lb).Sexually dimorphic, the females are slightly larger than the males. The dark tail measures slightly above 10 centimetres (3.9 in). It has short, spiky horns, around 5 centimetres (2.0 in) long and hidden in hair tufts. The subspecies show a great degree of variation in their colouration. The blue duiker bears a significant resemblance toMaxwell's duiker.
Activity isdiurnal (limited to daytime). Secretive and cautious, the blue duiker confines itself to the forest fringes.Territorial, individuals of opposite sexes form pairs and occupy territories, nearly 0.4–0.8 hectares (0.0015–0.0031 sq mi) large and marked bypreorbital gland secretions. The blue duiker feeds on fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forestcanopies in their habitat. The age whensexual maturity is gained has been given differently by different studies. The species ismonogamous, with pairs remaining together throughout the year. The length of the gestational period has been estimated from as little as four months to as long as seven months. Births occur throughout the year, though the birth rate might fall in the dry season. The calf is mainly kept in hiding and weaning occurs at 2.5 to 3 months.
The habitat consists of a variety of forests, includingold-growth,secondary, andgallery forests. Forests are preferred as these provide the animal with shelter through the denseunderstory and forage through the canopy. Though categorized asLeast Concern by the International Union for Conservation of Nature and Natural Resources (IUCN), the blue duiker is under threat from extensivebushmeat hunting across its range.
Thescientific name of the blue duiker isPhilantomba monticola. It is placed in thegenusPhilantomba, along withMaxwell's duiker (P. maxwelli) andWalter's duiker (P. walteri), and thefamilyBovidae. Thespecies was first described by Swedish naturalistCarl Peter Thunberg in 1789.[3] It is sometimes treated as a species ofCephalophus,[1] another genus of duikers, althoughPhilantomba has been recognised as a genus by zoologists such asPeter Grubb andColin Groves.[4] Owing to the remarkable similarities between the two species, some zoologists such asTheodor Haltenorth consider Maxwell's duiker as a race of the blue duiker.[3][5]
While thegeneric namePhilantomba has no clear origin, thespecific namemonticola has been derived from theLatin wordsmontis (mountain) andcolo (meaning "I cultivate" or "I inhabit"), in reference to its montane habitat.[6] The common name "blue" refers to one of its typical coat colours.[7] The common name of duiker comes from theAfrikaansduik orDutchduiker – both mean "diver", which refers to the practice of the animals to frequently dive into vegetation for cover.[8]
In 2012, Anne R. Johnston (of theUniversity of Orleans) and colleagues constructed acladogram of thesubfamilyCephalophinae (duiker), that includes the three generaCephalophus,Philantomba andSylvicapra, based onmitochondrial analysis.Philantomba was shown to bemonophyletic. It issister to the rest of thesubfamily, from which itdiverged nearly 8.73 million years ago (in the lateMiocene). The blue duiker split from Maxwell's duiker 2.68 to 5.31 million years ago.[9] This cladogram, however, did not include the newly discovered Walter's duiker. Marc Colyn (of theUniversity of Rennes 1) and colleagues, who had discovered this species in 2010, had prepared a similar cladogram (below) that included it.[10]
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As many as 16subspecies of the blue duiker have been proposed. In 1997,Jonathan Kingdon demarcated seven major populations of the species.[7] In 2001, Groves and Grubb identified the following subspecies, bifurcating them into two groups on the basis of their colouration and geographical occurrence:[3][11][12]
The grey-legged or northern subspecies
The red-legged or southern subspecies
The blue duiker is a smallantelope; in fact, it is the smallest duiker.[7] The head-and-body length is typically between 55 and 90 centimetres (22 and 35 in). It reaches 32–41 centimetres (13–16 in) at the shoulder and weighs nearly 3.5–9 kilograms (7.7–19.8 lb).[13]P. m. anchietae is the largest subspecies.[7]Sexually dimorphic, the females are slightly larger than the males.[6] The blue duiker is characterised by a flat forehead, large eyes, small ears with a line of white, large nostrils, a broad mouth and agile lips. The dark tail measures slightly above 10 centimetres (3.9 in). A remarkable feature of the tail is the row of white crinkly hairs on either flank that reflect light efficiently, so that when the animal moves its tail up and down, it looks like a luminous signal in the dark habitat.[7][13] The duiker has short, spiky horns, around 5 centimetres (2.0 in) long and hidden in hair tufts.[7][14] A row of minute pores surrounded by a few hairs in thepreorbital glands (near the eyes) secrete an opaque liquid consisting of 45 volatile compounds.[15] The pedal glands (near the hooves) produce a pungent, whitish fluid.[8]
The subspecies show a great degree of variation in their coloration. The coat can be a shade of blue, grey or brown, and even black. The grey-legged northern subspecies show a grey to brown coloration, with aposterior stripe that marks a transition from therump to the buttocks.P. m. congicus has a bright grey to black back, with dull grey flanks; a dark brown stripe marks the shift from the black rump to the lighter buttocks.P. m. sundevalli is similar, though the difference between the flanks and the rump is less notable.P. m. aequatorialis is paler and browner thanP. m. congicus with a less sharp transition. The stripe is fainter and the back darker inP. m. musculoides.P. m. lugens can be told apart from its darker coloration; the flanks and thedorsal parts are dark grey to brown, the underside grey and a black rump. The diminutiveP. m. melanorheus stands apart as well, with black dorsal parts, pinkish grey sides, and long thick fur.
_Cephalophus_monticola.png)
_Cephalophus_maxwelli.png)
The southern subspecies, on the other hand, have reddish tan legs and reddish coats.P. m. hecki is a light fawn to greyish black with light red flanks and a white underbelly; a change in tone can be observed as the rump is a darker reddish fawn. The palerP. m. defriensi is grey in the middle portion of the back, with red to fawn sides, and dark rump and tail.P. m. monticola, light grey to fawn with a reddish rump, is darker thanP. m. bicolor, that has reddish-orange flanks.P. m. anchietae is a pale grey or brown on the back with white underparts and a black tail; there is a clear transition from the grey sides andanterior parts to the reddish rump.P. m. simpsoni is distinguished by a facial stripe with whiteventral parts; the rump is redder than the flanks.[7]
The blue duiker bears a significant resemblance to Maxwell's duiker. However, the latter is nearly twice as large and heavy as the former, with a larger skull. While coloration is more uniform in Maxwell's duiker, the blue duiker shows two different colorations. Another point of difference is the pedal gland (in thehooves), which has a simpler opening in the blue duiker.[7][16] Walter's duiker is notably lighter in colour; the flanks are brown instead of grey.[10]
The blue duiker isdiurnal (active during the day). Secretive and cautious, it confines itself to the forest fringes.Territorial, individuals of opposite sexes form pairs and occupy territories, nearly 0.4–0.8 hectares (0.0015–0.0031 sq mi) large and marked by preorbital gland secretions.[14] The animal rubs the preorbital glands on trees and logs to mark its territory with the fluid produced by the glands.[8] A vocal bovid, bird-like chirps denote curiosity in the animal.[14] It can let out yowls typical of cats if distressed. A female not in oestrus will avoid the male's advances, and may even let out a whistling call.[7]
The diet consists of fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forestcanopies in their habitat.[14] Fungi,resin, particularlyexudates fromAlbizia species[7] and animal matter such as ants (which are licked from the ground)[17] may also be included in the diet. The blue duiker can sustain itself on dead foliage better than other duiker species.[7] A 1990 study analysed 12 stomachs and determined the content ofdicotyledonous leaves to be 70%, while fruits and seeds comprised 23% of the diets and fresh foliage was plenty and perennial. Fruits were, however, strongly preferred to foliage.[18] In 2001, American zoologistDon E. Wilson observed 18 stomachs, and concluded that nearly three-fourths were occupied by fruits, browse took 15 percent of the volume, while fungi and flowers took 5 percent each.[7] They may forage by tracking the movements of birds and monkeys.[13]
The age whensexual maturity is gained has been given differently by different studies. Wilson observed that females become mature before 13 months, and the minimum age was found to be eight months. He noted that males take longer to mature, nearly 11 to 14 months.[7] The species ismonogamous, with pairs remaining together throughout the year.[19] The length of the gestational period has been estimated from as short as four months[20] to as long as seven months.[21][22] The former estimate is supported by observations in theIturi Rainforest (Democratic Republic of Congo).[23] Births occur throughout the year,[24] though the birth rate might fall in the dry season.[7] The calf can start moving about on its own within 20 minutes of birth, and is nursed thrice a day. It is kept in hiding for most of the time. The nursing intervals become irregular towards weaning, which occurs at 2.5 to 3 months. Males visit their mates occasionally, though they disappear for about a month after the calf's birth to probably protect the calf.[19] Apostpartum oestrus occurs three to five days after the birth.[7]
This species can survive in a variety of forests, includingold-growth,secondary andgallery forests. Forests are preferred as these provide the animal with shelter through the denseunderstory and forage through canopy.[14] They can also be found in pockets of degraded and regenerated forests from the sea level up to an altitude of 3,000 metres (9,800 ft). This duiker can be found in several countries in the western, southern and eastern parts of Africa:Angola,Cameroon,Central African Republic, The Democratic Republic of Congo, Equatorial Guinea,Gabon,Kenya, Malawi, Mozambique,Nigeria,Rwanda, South Africa, South Sudan, Tanzania, Uganda, Zambia andZimbabwe.[1][25]
The blue duiker is categorized asLeast Concern by the International Union for Conservation of Nature and Natural Resources (IUCN). It is listed in Appendix II of theConvention on International Trade in Endangered Species (CITES). While the population trend is reasonably stable, the blue duiker is threatened by extensivebushmeat hunting across its range. Wilson claimed that the blue duiker has the greatest economic as well as ecological significance of any Africanungulate .[1] Blue duiker meat is an important source of nutrition in its range.[14] However, the blue duiker can survive despite human interference in its habitat.[1][25]
P. monticola occurs in the following protected areas across its range:Semuliki National Park (Uganda);Dja Faunal Reserve andLobéké National Park (Cameroon);Dzanga-Sangha Special Reserve andDzanga-Ndoki National Park (Central African Republic);Monte Alén National Park (Equatorial Guinea);Lopé National Park andGamba (Gabon);Odzala,Nouabalé-Ndoki andConkouati-Douli National Parks andLake Tele region (Congo-Brazzaville); theOkapi Wildlife Reserve andMaiko,Kahuzi-Biéga andSalonga National Parks (Congo-Kinshasa); and numerous others in Southern Africa.[1][25]
