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Philantomba monticolablue duiker

By Leila Siciliano

Geographic Range

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. (Ronald and Kranz, 2006; Waltert, et al., 2006)

Habitat

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. ("Philantomba monticola", 1999; Estes, 1991)

Physical Description

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. (Estes, 1991; Ralls, 1973; Ronald and Kranz, 2006)

  • Range mass
    4 to 6 kg
    8.81 to 13.22 lb
  • Range length
    55 to 72 cm
    21.65 to 28.35 in

Reproduction

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. (Boehner, et al., 1984; "Philantomba monticola", 1999; Estes, 1991)

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. (Boehner, et al., 1984; "Philantomba monticola", 1999; Estes, 1991)

  • 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

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)

  • 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

Lifespan / Longevity

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. ("Blue Duiker", 2008; Willette, et al., 2002; de Magalhaes, et al., 2002)

  • Range lifespan
    Status: wild
    12 (high) years
  • Range lifespan
    Status: captivity
    16 (high) years
  • Typical lifespan
    Status: captivity
    10 to 15 years

Behavior

Blue duikers live in dense patches of forest in monogamous pairs. Adults spend the day moving around the territory foraging for food, in the form of 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 will often forage in different parts of their range 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. Pair members 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 the 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

Home Range

Blue duikers are among the most widespread of duiker species. This can be attributed in part to their minimal requirements for patches of continuous habitat and 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 problem for blue duikers caused by humans appears to be the disassembling of firewood piles, as these duikers use hallows in woodpiles as areas 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 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. (Estes, 1991)

Food Habits

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
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • flowers
  • Other Foods
  • fungus

Predation

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'. ("Philantomba monticola", 1999; Estes, 1991; "Blue Duiker", 2008; "The Living Africa", 1998)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

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. (Dierenfeld, et al., 1995; Feer, 1995; "Blue Duiker", 2008)

Mutualist Species
Commensal/Parasitic Species

Economic Importance for Humans

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
  • food

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)

Conservation Status

Currently, blue duikers are listed as 'Least Concern' on the IUCN Red List of Threatened Species.

Contributors

Leila Siciliano (author), Michigan State University, Barbara Lundrigan (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

agricultural

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.

chemical

uses smells or other chemicals to communicate

cryptic

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.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

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

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

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).

monogamous

Having one mate at a time.

motile

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.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

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

sedentary

remains in the same area

sexual

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.

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

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

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

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

References

Honolulu Zoo. 2008. "Blue Duiker" (On-line). Honolulu Zoo. Accessed March 11, 2010 at http://www.honoluluzoo.org/blue_duiker.htm.

Brent Hoffman. 1999. "Philantomba monticola" (On-line). Ultimate Ungulate. Accessed March 11, 2010 at http://www.ultimateungulate.com/Artiodactyla/Philantomba_monticola.html.

Think Quest Team. 1998. "The Living Africa" (On-line). Blue Duiker: Cephalophus monticola. Accessed March 12, 2010 at http://library.thinkquest.org/16645/wildlife/blue_duiker.shtml.

Boehner, J., K. Volger, H. Hendrichs. 1984. Breeding Dates of Blue Duikers (Cephalophus monticola). Zeitschrift fuer Saeugetierkunde, 49/5: 306-314.

Bowman, V., A. Plowman. 2002. Captive Duiker Management at the Duiker and Mini-Antelope Breeding and Research Institute (Dambari), Bulawayo, Zimbabwe. Zoo Biology, 21: 161-170.

Dierenfeld, E., W. Braselton, H. Puche, R. Cook. 1995. Health Evaluation of Five Sympatric Duiker Species (Cephalophus Species). Journal of Zoo and Wildlife Medicine, 26/4: 485-502.

Dierenfeld, E., P. Mueller, M. Hall. 2002. Duikers: Native Food Composition, Micronutrient Assessment, and Implications for Improving Captive Diets. Zoo Biology, 21: 185-196.

Estes, R. 1991. The Behavior Guide to African Mammals. Berkeley and Los Angeles, California: University of California Press.

Feer, F. 1995. Seed Dispersal in African Forest Ruminants. Journal of Tropical Ecology, 11/4: 683-689.

Hanekom, N., W. Wilson. 1991. Blue Duiker Philantomba monticola Densities in the Tsitsikamma National Park and Probable Factors Limiting These Populations. Koedoe, 34/2: 107-120.

Kranz, K. 1991. Monogamy in the Dik-Dik. Applied Animal Behaviour Science, 29: 87-105.

Lawes, M., P. Mealin, S. Piper. 2000. Patch Occupany and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South Africa. Conservation Biology, 14/4: 1088-1098.

Molloy, L., J. Hart. 2002. Duiker Food Selection Palatability Trials Using Natural Foods in the Ituri Forest, Democratic Republic of Congo. Zoo Biology, 21: 149-159.

Newing, H. 2001. Bushmeat Hunting and Management: Implications of Duiker Ecology and Interspecific Competition. Biodiversity and Conservation, 10/1: 99-108.

Ralls, K. 1973. Mammalian Species: Cephalophus maxwellii. American Society of Mammalogists, 31: 1-4.

Ronald, K., K. Kranz. 2006. Duikers. Pp. 542-545 in D Macdonald, ed. Encyclopedia of Mammals. London: The Brown Reference Group.

Waltert, M., S. Heber, S. Riedelbauch, J. Lien. 2006. Estimates of Blue Duiker (Cephalophus monticola) Densities from Diurnal and Nocturnal Line Transects in the Korup Region, Southwestern Cameroon. African Journal of Ecology, 44: 290-292.

Willette, M., T. Norton, C. Miller, M. Lamm. 2002. Veterinary Concerns of Captive Duikers. Zoo Biology, 21: 197-207.

Yasuoka, H. 2006. The Sustainability of Duiker (Cephalophus Spp.) Hunting for the Baka Hunter-Gatherers in Southeastern Cameroon. African Study Monographs, 33: 95-120.

de Magalhaes, J., A. Budovsky, G. Lehmann, J. Costa, Y. Li, V. Fraifeld, G. Church. 2002. "The Human Ageing Genomic Resources: online databases and tools for biogerontologists" (On-line). AnAge. Accessed March 10, 2010 at http://genomics.senescence.info/species/entry.php?species=Cephalophus_monticola.

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