 Cephalophus
adersi
Aders's duiker |
Taxonomy | Description
| Reproduction | Ecology
| Behavior | Distribution
| Conservation | Remarks
| Literature |
| Taxonomy
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Cephalophus adersi [Thomas, 1918].
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Citation: Ann. Mag. Nat. Hist., [ser. 9], 2:151
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Type locality: Tanzania, Zanzibar.
The taxonomic record (above) is taken from Wilson and Reeder (1993).
Aders's duiker is usually placed within the subgenus
Cephalophorus [Gray, 1842] (Nowak, 1991). The taxonomic status
of C. adersi has been debated by authorities - it is considered by
some to be a subspecies of Cephalophus harveyi or C. natalensis,
and has been lumped by others into a superspecies with C. natalensis
and C. callipygus (see Wilson, 1987). C. adersi is monotypic
(Wilson, 1987).
General Characteristics
Aders's duiker is a small duiker, weighing no more than about 12 kg (Kingdon,
1982). However, there appears to be clinal variation in weight, with
individuals regularly weighing 12 kg in mideastern Zanzibar, but only about
7.5 kg in the extreme south of the island (Kingdon, 1982). Head and
body length are 66-72 cm, and shoulder height is about 30 cm (Kingdon, 1982).
Reported measurements for Aders's duiker (Cephalophus adersi) |
| Source |
Adult Weight |
Head & Body Length |
Shoulder Height
|
Tail Length |
| Kingdon, 1982 |
6.5-12 kg |
66-72 cm |
30-32 cm |
9-12 cm |
| Wilson, 1987 |
6-12 kg |
66-62 cm [sic] |
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9-12 cm |
The pelage of Aders's duiker is soft and silky, with no marked change in
texture from the neck to the body proper (Kingdon, 1982). The overall
color is a tawny red, which grows somewhat greyer on the neck (Kingdon, 1982;
Wilson, 1987). Specimens from the Jozani forest of southern Zanzibar
are paler in coloration (Kingdon, 1982). A distinguishing characteristic
of this duiker species is the wide white band on the rump which runs cranially,
merging with the lighter underparts (Kingdon, 1982; Wilson, 1987).
Additionally, there is white "freckling" on the reddish legs, accentuated
by a black and white spot just above hooves (Kingdon, 1982).
The head bears a reddish crest typical of most duiker species (Kingdon, 1982).
On either side of this crest are found the short, simple spiked horns,
which grow 3-6 cm in length (Kingdon, 1982). The muzzle is pointed,
and the nose has a flat front (Kingdon, 1997). The ears measure 7-8.3
cm long, and there is a marked cowlick or whorl of hair on the nape of the
neck (Kingdon, 1982).
Ontogeny and Reproduction
Virtually nothing is known about the reproduction of C. adersi.
Kingdon (1997) reports that this species breeds throughout the year.
Ecology and Behavior
A generalized species, Aders's duiker inhabits coastal forests, woodlands,
and thickets (Kingdon, 1982; Wilson, 1987). This species can live in
quite dry scrub near the sea or among coral outcrops - in Zanzibar they are
restricted to tall thicket forest growing on waterless coral rag (Kingdon,
1982; Kingdon, 1997). In Arabuko Sokoke (Kenya) Aders's duikers are
most often trapped within Cynometra vegetation, especially on "red
soil" (Kanga, 1995). C. adersi is sympatric with C. harveyi
on the mainland and with C. monticola sundevalli on Zanzibar, although
nothing is known regarding their ecological separation (Kingdon, 1982).
Aders's duiker has been reported by Kingdon (1997) to live in pairs which
defend a territory. They are almost completely diurnal - it is very
rare to observe them at night (Kingdon, 1982). Feeding occurs from
dawn to around 1100 hours, which is followed by a period of rest and rumination
(Kingdon, 1997). A about 1500 hours Aders's duikers generally become
active, and will continue foraging until nightfall (Kingdon, 1997). This
species is very shy, alert, and sensitive to sound (Kingdon, 1997). As
a result, common methods of hunting include the brute-force method of driving
the duikers into nets with dogs, or silent ambush at feeding sites (Kingdon,
1997).
Aders's duiker feeds primarily on fallen flowers, fruits, leaves - often
picking up scraps dropped by monkeys and birds foraging in the trees (Kingdon,
1997). C. adersi shows a particular dependence on the flowers
and berries which grow prolifically from trees common to the area, such as
ebony (Diospyros consolataei), kudu berry (Cassine aethiopica),
and bush guarri (Euclea schimperi), and bushes such as turkey barry
(Canthium spp.) and Polyspheria (Kingdon, 1997). In addition
to these foods, they will eat sprouts, buds, and other fresh growth found
at ground level (Kingdon, 1997). This duiker species can apparently
manage without drinking (Kingdon, 1982).
Distribution
The range of Aders's duiker is restricted to two isolated locales - the Arabuko
Sokoke Forest, a remnant of lowland forest in coastal Kenya covering 420
km2, and Tanzania's Zanzibar Island (Kanga, 1995).
Countries: Kenya, United Republic of Tanzania (IUCN, 2002).
Range Map (Redrawn from IEA, 1998, East, 1988)
Conservation Status
Aders's duiker is classified as endangered (Criteria C1) by the IUCN (2002),
but is not listed by CITES. Habitat destruction and fragmentation,
as a result of expanding agriculture and harvesting of forest products, is
one of several threats experienced by this rare duiker (IUCN, 2002). These
activities people closer to the already restricted range of this species
with the result that free-ranging and feral dogs are becoming an increasing
threat (Kingdon, 1997). Dogs are known to have destroyed
an introduced population of Aders's duiker on Funzi Island, where these antelope
had previously thrived (Kingdon, 1997). However, perhaps the most serious
pressure experienced by this species is over-hunting (Kanga, 1995; IUCN,
2002). At Mtende, Zanzibar, Aders's duiker has been estimated to form
70% of hunters' antelope kills, although since the late 1980's trapping success
has been extremely low (Kanga, 1995; Kingdon, 1997). Aders's duiker
is highly sought in the market place due to its "sweet" meat and beautiful
skin (Kanga, 1995). It is estimated that fewer than 1,400 individuals
remain in the wild population, representing a 50-75% decrease since 1982
(East, 1999).
Remarks
Aders's duiker was interpreted by Kingdon (1982) as representative of the
primitive evolutionary stock from which all modern duiker species radiated.
As a result, it is sometimes known as the dwarf red duiker (Kingdon,
1982). Its restricted range has also given rise to the name "Zanzibar
duiker". The name duiker ("DIKE-er") is Afrikaans for "diver",
a name which is derived from the habit of diving into the undergrowth when
alarmed demonstrated by many members of the genus Cephalophus. Dr.
W. Mansfield Aders, D.Sc., was a Government Zoologist with the Zanzibar
Government Service.
Kephale (Greek) the head; lophus (Greek) a crest: referring
to the tuft of hair on the forehead.
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Local names (from Kingdon, 1982; Kanga, 1995; Kingdon, 1997)
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Paa nunga, Nunga [Kiswahili]
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Kungu marara [Kipokomo]
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Harake [Giriama]
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French
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Céphalophe de Aders (Kingdon, 1997)
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German
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Adersducker (Kingdon, 1997)
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Literature
Cited
East, R. [editor]. 1988. Antelope Global Survey and Regional
Action plans, Part I: East and North East Africa. IUCN/SSC Antelope Specialist
Group.
East, R. [compiler]. 1999. African Antelope Database 1998. IUCN/SSC Antelope
Specialist Group. Gland, Switzerland and Cambridge, UK: IUCN.
IEA (Institute of Applied Ecology) 1998. Cephalophus adersi.
In African Mammals Databank - A Databank for the Conservation
and Management of the African Mammals Vol 1 and 2. Bruxelles: European
Commission Directorate. Available online at
http://gorilla.bio.uniroma1.it/amd/amd335b.html
IUCN ( International Union for Conservation of Nature and Natural Resources).
2002. 2002 IUCN Red List of Threatened Species. Available online at
http://www.redlist.org
Kanga, E. M. 1995. Arabuko Sokoke Forest duiker survey. EANHS
Bulletin 25(3): 49-50.
Kingdon, J. 1982. East African Mammals: An atlas of evolution in Africa.
London: Academic Press.
Kingdon, J. 1997. The Kingdon Field Guide to African Mammals. Academic
Press, London and New York: NaturalWorld.
Nowak, R. M. [editor]. 1991. Walker's Mammals of the World (Fifth Edition).
Baltimore: The Johns Hopkins University Press.
Wilson, D. E., and D. M. Reeder [editors]. 1993. Mammal Species of the World
(Second Edition). Washington: Smithsonian Institution Press.
Available online at
http://nmnhwww.si.edu/msw/
Wilson, V. J. [compiler] 1987. Action plan for duiker conservation -
IUCN/SSC Antelope Specialist Group and Chipangali Wildlife Trust.
Additional Resources
Archer, A. L. 1994. A survey of hunting techniques and the results
thereof of two species of duiker and suni antelopes in Zanzibar, Commission
for Natural Resources, Zanzibar, FINNIDA, Finnish Forest and Park Service,
Zanzibar.
East, R. [editor]. 1996. Antelope survey update. IUCN/SSC Antelope
Specialist Group: n° 2.
Eves, H. 2000. Duikers: A primary target for Africa's bushmeat trade.
Animal Keepers' Forum 27(11): 497-505.
Finnie, D. 2002. Ader’s duiker (Cephalophus adersi) species recovery
plan (revised). Zanzibar Forestry Technical Paper 124. Zanzibar: Dept.
of Commercial Crops, Fruits and Forestry.
Heckel, J. O. 1997. Weiteres zum Status des Aders-Duckers
(Cephalophus adersi) [Further information on the status of Aders'
duiker (Cephalophus adersi)]. Zoologische Gesellschaft fuer
Arten und Populationsschutz E. V. Mitteilungen 13(1): 4-6.
Muller, P. 1996. Zanzibars Zwergantilopen [Zanzibar's dwarf
antelopes]. Zoologische Gesellschaft fuer Arten und Populationsschutz E.
V. Mitteilungen 12(2): 16-18.
van Vuuren, B. J., and T. J. Robinson. 2001. Retrieval of four
adaptive lineages in duiker antelope: Evidence from mitochondrial DNA sequences
and fluorescence in situ hybridization. Molecular Phylogenetics and
Evolution 20(3): 409-425.
Williams J. M., A. A. Mwinyi, and R. Ali. 1996. A population survey of the
three mini-antelope: Ader's duiker, Zanzibar blue duiker, and suni of Unguja,
Zanzibar. Gnusletter 15(2): 6-7.
Williams, A., A. Mwinyi, and J. Said. 1996. A Population Survey of the
Mini-antelope Ader's duiker Cephalophus adersi, Zanzibar blue duiker
Cephalophus monticola sudevalli, and Suni Neotragus moschatus
moschatus of Unguja, Zanzibar. Unpublished report to the Commission for
Natural Resources, Zanzibar.
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