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.
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 a
clear line of vision.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- forest
- rainforest
- Other Habitat Features
- agricultural
Physical Description
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- ornamentation
Reproduction
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.
- Mating System
- monogamous
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.
- 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
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- male
- female
-
provisioning
Lifespan/Longevity
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.
Behavior
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.
- Key Behaviors
- cursorial
- terricolous
- diurnal
- motile
- sedentary
- territorial
- social
Home Range
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.
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.
- Other Communication Modes
- pheromones
- scent marks
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.
- 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
,
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'.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
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
.
- monkeys ( Cercopithecidae )
- nematodes ( Nematoda )
- coccidian parasites ( Coccidia )
- blood worms ( Strongyles )
- roundworms ( Trichuridae )
- ruminant tapeworms ( Moniezia )
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.
- 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.
Conservation Status
Currently, blue duikers are listed as 'Least Concern' on the IUCN Red List of Threatened Species.
Additional Links
Contributors
Leila Siciliano (author), Michigan State University, Barbara Lundrigan (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- 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.
- agricultural
-
living in landscapes dominated by human agriculture.
- 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.
- 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.
- 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.
- monogamous
-
Having one mate at a time.
- 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).
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- young precocial
-
young are relatively well-developed when born
- female parental care
-
parental care is carried out by females
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- 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
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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.
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- frugivore
-
an animal that mainly eats fruit
- granivore
-
an animal that mainly eats seeds
References
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 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 .
Brent Hoffman. 1999. " Philantomba monticola " (On-line). Ultimate Ungulate. Accessed March 11, 2010 at http://www.ultimateungulate.com/Artiodactyla/Philantomba_monticola.html .
Honolulu Zoo. 2008. "Blue Duiker" (On-line). Honolulu Zoo. Accessed March 11, 2010 at http://www.honoluluzoo.org/blue_duiker.htm .
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 .