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 a clear line of vision. ("Philantomba monticola", 1999; Estes, 1991)
- Other Habitat Features
Blue duikers are the smallest of the duiker species, weighing no more than 4 to 6 kg. They are generally 55 to 72 cm long, with a 7 to 12.5 cm tail that is black with a white underside. Their coat color varies depending on their range, but is typically brown, often with a blue tint. Males have a pair of grooved horns that are about 5 cm in height. Horns may also be present in females, although not as frequently. Blue duikers are very similar in appearance to Maxwell's duikers. They can be distinguished by several key features, most notably the smaller skull and narrower nasal passage seen in blue duikers. (Estes, 1991; Ralls, 1973; Ronald and Kranz, 2006)
- Sexual Dimorphism
- Range mass
- 4 to 6 kg
- 8.81 to 13.22 lb
- Range length
- 55 to 72 cm
- 21.65 to 28.35 in
Female blue duikers become sexually mature at 9 to 12 months and males become sexually mature at 12 to 18 months. At which point, they find a mate and remain paired for life. Although blue duikers are considered monogamous, males occasionally mate outside of their pair. (Boehner, et al., 1984; "Philantomba monticola", 1999; Estes, 1991)
- Mating System
Pairs of blue duikers 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 throughout the 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. Their gestation period lasts anywhere from 196 to 216 days and typically produces 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, between 1 and 1.5 years of age, whereas males leave 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. (Boehner, et al., 1984; "Philantomba monticola", 1999; Estes, 1991)
- Key Reproductive Features
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Mated pairs typically associate only with 1 or 2 offspring at a time until they mature at 1 to 2 years of age, so their breeding interval is likely once yearly.
- Breeding season
- Blue duikers breed throughout the year.
- Range number of offspring
- 1 to 2
- Average number of offspring
- 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
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. (Boehner, et al., 1984; Estes, 1991)
In captivity, blue duikers typically live 10 to 15 years, but the oldest recorded captive individual survived until it was nearly 16 years old. In the wild, their lifespan is shorter, with the oldest known individual surviving to age 12. Captive duikers are commonly afflicted with several illness, most notably 'sloshing syndrome' or rumen hypomotility syndrome. This illness is characterized by a build-up within the rumen caused by limited activity. ("Blue Duiker", 2008; Willette, et al., 2002; de Magalhaes, et al., 2002)
- Range lifespan
- 12 (high) years
- Range lifespan
- Range lifespan
- 16 (high) years
- Range lifespan
- Typical lifespan
- 10 to 15 years
- Typical lifespan
Blue duikers live in dense patches of forest in monogamous pairs. Adults spend the day moving through their territory foraging for leaves and fallen fruit. These animals are diurnal, but have been known to display nocturnal behavior when the female is in estrus. The adult male and female often forage in different parts of their territory during the day, but periodically come back together. Likewise, they may spend all, or part of the night in different parts of their territory, or together. Pairs will defend their territory from other duikers by assuming a posture known as 'low-horn presentation'. Usually, the intruding individual will flee once confronted, but occasionally a battle ensues. Battles between blue duikers involve ramming one another repeatedly with their horns. These fights typically end without injury, although occasionally an individual will suffer stab wounds. (Bowman and Plowman, 2002; Estes, 1991; Kranz, 1991)
- Range territory size
- 7000 to 40000 m^2
Blue duikers are among the most widespread duiker species. This can be attributed in part to their minimal requirements for patches of continuous habitat and their ability to survive in disturbed areas. Blue duikers have a minimum critical patch area of 0.7 ha, but typically maintain a home range of 2.5 to 4 ha. They can be found near human inhabited areas, and do not appear to be averse to commercial plantations, which they sometimes use as corridors between patches of appropriate habitat. The largest anthropogenic issues for the species appears to be the disassembling of firewood piles, as these duikers use hallows in woodpiles for roosting. (Estes, 1991; Lawes, et al., 2000)
Communication and Perception
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 their tail. Auditory signals include snorting, whistling, hitting an object with their horns, and stamping their feet. Each of these displays conveys different messages and may communicate alarm or sexual excitement. Their primary visual display is tail flicking; flicking their 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. (Estes, 1991)
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. (Dierenfeld, et al., 2002; Estes, 1991; Molloy and Hart, 2002)
- Animal Foods
- Plant Foods
- seeds, grains, and nuts
- Other Foods
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, pythons, civets, crowned eagles, monitors, and humans. They primarily use their visual and auditory senses to detect predators. Once a predator is spotted, blue duikers typically communicate alarm, which may include snorting, stamping, whistling, or flicking their tail, depending on the degree of danger. Once this danger message has been received, duiker's generally respond by fleeing. 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'. ("Philantomba monticola", 1999; Estes, 1991; "Blue Duiker", 2008; "The Living Africa", 1998)
- Anti-predator Adaptations
Blue duikers live in forested areas and feed primarily on fallen fruit. The fruit 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 host several parasites, externally, they are often afflicted with ticks, internally, they have may several species of Nematoda, Coccidia, Strongyles, Trichuridae, and Moniezia. (Dierenfeld, et al., 1995; Feer, 1995; "Blue Duiker", 2008)
- monkeys (Cercopithecidae)
Economic Importance for Humans: Positive
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. (Newing, 2001; Yasuoka, 2006)
- Positive Impacts
Economic Importance for Humans: Negative
Although this species sometimes occupies plantation fields, it is not known to be harmful to crops or humans. (Lawes, et al., 2000)
Currently, blue duikers are listed as 'Least Concern' on the IUCN Red List of Threatened Species.
Leila Siciliano (author), Michigan State University, Barbara Lundrigan (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
living in landscapes dominated by human agriculture.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- active during the day, 2. lasting for one day.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- female parental care
parental care is carried out by females
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
chemicals released into air or water that are detected by and responded to by other animals of the same species
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- scent marks
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- sexual ornamentation
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- year-round breeding
breeding takes place throughout the year
- young precocial
young are relatively well-developed when born
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