The diminutive size of blue duikers leaves them vulnerable to many species, including but not limited to hyenas, wild dogs, African golden cats, leopards, crocodiles, baboons, python, civets, crowned eagles, monitors, and humans. They primarily use their visual and auditory senses in detecting predators. Once a predator is spotted, blue duikers will typically communicate alarm, which may include snorting, stamping, whistling, or flicking the tail, depending on the degree of danger. Once this message of danger has been received, a duiker's response is typically flight. Their long hind limbs make them excellent jumpers, able to quickly dive into dense vegetation and disappear. It is this ability that gave duikers their name, for the Afrikaans word meaning 'divers'.
Known Predators:
Anti-predator Adaptations: cryptic
Blue duikers are the smallest of the duiker species, weighing no more than 4 to 6 kg. They are typically 55 to 72 cm long, with a 7 to 12.5 cm tail that is black with a white underside. Coat color varies, depending on where the animal lives but the coat is typically brown, often with a blue tint. All males have a pair of grooved horns that are about 5 cm in height. Females may have horns as well, however, horns are frequently not present in females. Blue duikers are very similar in appearance to Maxwell's duikers (Philantomba maxwellii). However, the two can be distinguished by several key features, most notably blue duikers have a smaller skull, with a narrower nasal passage.
Range mass: 4 to 6 kg.
Range length: 55 to 72 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: ornamentation
In captivity, blue duikers typically live for 10 to 15 years, but the oldest recorded captive individual survived until it was nearly 16 years of age. In the wild, lifespan is shorter, with the oldest known individual surviving to age 12. Captive duikers are commonly afflicted with several illness, most notable of those is 'sloshing syndrome' or rumen hypomotility syndrome. This illness is characterized by a build-up within the rumen caused by limited activity.
Range lifespan
Status: wild: 12 (high) years.
Range lifespan
Status: captivity: 16 (high) years.
Typical lifespan
Status: captivity: 10 to 15 years.
Blue duikers can be found in a variety of forested areas, including rain forests, riverine forests, dense thickets, and montane forests. They are often found near human dwellings, and may use plantations as corridors in their habitat. Piles of dead trees or lumber are sometimes used as resting sites. However, the majority of their time is spent resting in the open or at the base of a tree; this allows them to keep their line of vision clear.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: agricultural
Blue duikers use auditory, visual, olfactory, and tactile senses for communication. They have several methods of displaying alarm to a mate or offspring, including vocalizing and flicking the tail. Auditory signals include snorting, whistling, hitting an object with the horns, and stamping the feet. Each of these displays conveys different messages and may communicate alarm or sexual excitement. Their primary visual display is tail flicking; flicking the black tail reveals a white underside, which is believed to communicate imminent danger. Blue duikers have several scent glands, the most notable of which are the preorbital glands. Preorbital glands are thought to be important in communicating social acceptance and territory ownership. Pair members may scent mark each other, their offspring, or trees in their home range. Individuals often lick one another, a behavior that is thought to indicate social acceptance. Licking is especially evident when a male is courting a female.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Currently, blue duikers are listed as 'Least Concern' on the IUCN Red List of Threatened Species.
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
Although this species sometimes occupies plantation fields, it is not known to be harmful to crops or humans.
Blue duikers are among the most common duikers hunted for bushmeat. Many human groups living near the Congo basin rely heavily on the meat obtained from duikers for food and income.
Positive Impacts: food
Blue duikers live in forested areas and feed primarily on fallen fruit. The fruit that they find on the forest floor is often dislodged by monkeys that inhabit the same areas. In addition to fruit, blue duikers feed on seeds, however, they apparently do not aid in seed dispersal, because they fully masticate their food. Blue duikers may play host to several parasites. Externally, they are often afflicted with ticks. Internal parasites include several species of Nematoda, Coccidia, Strongyles, Trichuridae, and Moniezia.
Mutualist Species:
Commensal/Parasitic Species:
Blue duikers are frugivores and primarily feed on fallen ripe and unripe fruit, seeds, flowers, and fungi. They are ruminants, but have a relatively small rumen, which results in a rapid rate of food turnover. In association with rapid turnover, they prefer foods that are low in cellulose and starch with moderate fiber and protein content. They are, however, capable of digesting foods that are relatively high in tannins. Blue duikers spend up to 67 to 76% of their waking hours foraging for food within their territory.
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts; fruit; flowers
Other Foods: fungus
Primary Diet: herbivore (Frugivore , Granivore )
Philantomba monticola, commonly known as the blue duiker, is found throughout Central and Southern Africa. Its range includes Nigeria to Gabon and Kenya to South Africa.
Biogeographic Regions: ethiopian (Native )
Blue duikers become sexually mature at 9 to 12 months for females and 12 to 18 months for males. Once sexually mature, they find a mate and remain paired for life. Although blue duikers are considered monogamous, males occasionally breed with other females.
Mating System: monogamous
Blue duikers are social animals and display a variety of social behaviors, but they do not form large groups, instead associating as mated pairs. An important aspect of behavior is their use of preorbital scent glands, which both genders use to mark their mate. Licking behavior is also displayed and is believed to indicate social acceptance.
Blue duiker pair members remain together throughout the year, spending much of their time in close proximity. Seasonality does not appear to influence their reproduction, as they continue to produce offspring without regard to time of year. After the female calves, the male leaves the territory for approximately one month, during which time other males may enter the territory. The return of the female's mate drives other males away.
Blue duikers have a gestation period lasting anywhere from 196 to 216 days and typically produce only one calf per reproductive event. Newborn calves weigh about 10% of the mother's body weight. After calving, the female conceals her offspring, and for the first several weeks after birth, the majority of contact between the calf and female takes place during nursing. Eventually, when the calf is more mature, it spends more time with its mother. The calf is weaned between 2.5 and 3 months of age, and eventually leaves the territory on its own accord. Female calves typically leave when they are sexually mature, which is between 1 and 1.5 years of age, and males when they are fully grown, at about 2 years of age. Usually, only one offspring associates with the parents at any one time, but occasionally a monogamous pair will share its territory with two offspring of different ages.
Breeding interval: Breeding interval is not reported, although mated pairs typically associated only with 1 or 2 offspring at a time until they mature at 1 to 2 years old, so breeding interval is likely to be once yearly.
Breeding season: Blue duikers breed throughout the year.
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 196 to 216 days.
Range weaning age: 10 to 12 weeks.
Range time to independence: 1 to 2 years.
Range age at sexual or reproductive maturity (female): 9 to 12 months.
Range age at sexual or reproductive maturity (male): 12 to 18 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Blue duiker calves are extremely precocial and are able to run within 20 minutes of birth. The mother typically allows the calf to nurse approximately 3 times a day for the first month, after which the mother reduces nursing events until the calf is weaned at 2.5 to 3 months. Initially, the male is absent, taking leave shortly after the calf is born, and returning approximately one month later. However, he does not travel far, and does occasionally come back and spend time with his mate. It is believed that the male leaves his territory to aid in the protection of his offspring.
Parental Investment: precocial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female)
The blue duiker (Philantomba monticola) is a small antelope found in central, southern and eastern Africa. It is the smallest species of duiker. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789. 12 subspecies 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 to Maxwell's duiker.
Activity is diurnal (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 by preorbital gland secretions. The blue duiker feeds on fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forest canopies in their habitat. The age when sexual maturity is gained has been given differently by different studies. The species is monogamous, 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, including old-growth, secondary, and gallery forests. Forests are preferred as these provide the animal with shelter through the dense understory and forage through the canopy. Though categorized as Least Concern by the International Union for Conservation of Nature and Natural Resources (IUCN), the blue duiker is under threat from extensive bushmeat hunting across its range.
The scientific name of the blue duiker is Philantomba monticola. It is placed in the genus Philantomba, along with Maxwell's duiker (P. maxwelli) and Walter's duiker (P. walteri), and the family Bovidae. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789.[3] It is sometimes treated as a species of Cephalophus,[1] another genus of duikers, although Philantomba has been recognised as a genus by zoologists such as Peter Grubb and Colin Groves.[4] Owing to the remarkable similarities between the two species, some zoologists such as Theodor Haltenorth consider Maxwell's duiker as a race of the blue duiker.[3][5]
While the generic name Philantomba has no clear origin, the specific name monticola has been derived from the Latin words montis (mountain) and colo (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 the Afrikaans duik or Dutch duiker – 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 the University of Orleans) and colleagues constructed a cladogram of the subfamily Cephalophinae (duiker), that includes the three genera Cephalophus, Philantomba and Sylvicapra, based on mitochondrial analysis. Philantomba was shown to be monophyletic. It is sister to the rest of the subfamily, from which it diverged nearly 8.73 million years ago (in the late Miocene). 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 the University of Rennes 1) and colleagues, who had discovered this species in 2010, had prepared a similar cladogram (below) that included it.[10]
PhilantombaBlue duiker (P. monticola)
Maxwell's duiker (P. maxwelli)
Walter's duiker (P. walteri)
As many as 16 subspecies 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 small antelope; 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 the preorbital 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 a posterior stripe that marks a transition from the rump 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 than P. m. congicus with a less sharp transition. The stripe is fainter and the back darker in P. m. musculoides. P. m. lugens can be told apart from its darker coloration; the flanks and the dorsal parts are dark grey to brown, the underside grey and a black rump. The diminutive P. 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 paler P. 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 than P. 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 and anterior parts to the reddish rump. P. m. simpsoni is distinguished by a facial stripe with white ventral 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 heavier 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 the hooves), 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 is diurnal (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 forest canopies in their habitat.[14] Fungi, resin, particularly exudates from Albizia 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 of dicotyledonous 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 zoologist Don 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 when sexual 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 is monogamous, 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 the Ituri 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] A postpartum oestrus occurs three to five days after the birth.[7]
This species can survive in a variety of forests, including old-growth, secondary and gallery forests. Forests are preferred as these provide the animal with shelter through the dense understory 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 and Zimbabwe.[1][25]
The blue duiker is categorized as Least Concern by the International Union for Conservation of Nature and Natural Resources (IUCN). It is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). While the population trend is reasonably stable, the blue duiker is threatened by extensive bushmeat hunting across its range. Wilson claimed that the blue duiker has the greatest economic as well as ecological significance of any African ungulate .[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 and Lobéké National Park (Cameroon); Dzanga-Sangha Special Reserve and Dzanga-Ndoki National Park (Central African Republic); Monte Alén National Park (Equatorial Guinea); Lopé National Park and Gamba (Gabon); Odzala, Nouabalé-Ndoki and Conkouati-Douli National Parks and Lake Tele region (Congo-Brazzaville); the Okapi Wildlife Reserve and Maiko, Kahuzi-Biéga and Salonga National Parks (Congo-Kinshasa); and numerous others in Southern Africa.[1][25]
The blue duiker (Philantomba monticola) is a small antelope found in central, southern and eastern Africa. It is the smallest species of duiker. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789. 12 subspecies 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 to Maxwell's duiker.
Activity is diurnal (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 by preorbital gland secretions. The blue duiker feeds on fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forest canopies in their habitat. The age when sexual maturity is gained has been given differently by different studies. The species is monogamous, 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, including old-growth, secondary, and gallery forests. Forests are preferred as these provide the animal with shelter through the dense understory and forage through the canopy. Though categorized as Least Concern by the International Union for Conservation of Nature and Natural Resources (IUCN), the blue duiker is under threat from extensive bushmeat hunting across its range.
