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Artiodactyla
Id code: amd339Bovidae
Cephalophus weynsii
Thomas, 1901
(Eng) Weyns' duiker
(Fre) Céphalophe de Weyns
Taxonomic notes
Often considered as the eastern form of C. callipygus, this species is regarded as distinct here (Wilson & Reeder, 1993; East, 1996), pending a taxonomic revision of the red duikers group.
IUCN threat category
Lower Risk, near threatened (LR: nt).
Available information
The only ecological study conducted on this species is the one by Nummelin (1990), which describes its habitat use in virgin and logged areas of the Kibale Forest (Uganda). Its presence in Ethiopia and Rwanda is discussed respectively in Yalden et al. (1996) and Monfort (1992). Status and distribution are analysed in East (1988, 1990); the author also includes a description of the habitat in which it occurs.
Known extent of occurrence
Weyns’ duiker is widespread in central Africa, being recorded for Burundi, Kenya, Rwanda, Sudan, Tanzania, Uganda and former Zaire (East, 1996). Its distribution map was obtained from Kingdon (1971-77), then updated using East (1988, 1990) as indicated by Dr. R. East (23 June '97) (Fig. 8.6.63.a).
Categorical-discrete (CD) distribution model
The species inhabits lowland and montane forests (East, 1988, 1990).
Based on these environmental preferences, the following scores were assigned (Fig. 8.6.63.b) (8.6.63.a):
|
Score |
|
|
1 |
Lowland, montane forests. |
|
2 |
Forest mosaics. |
|
3 |
Savannas and croplands. |
|
suitable |
moderately suitable |
unsuitable |
Total |
||||
|
km2 |
% |
km2 |
% |
km2 |
% |
km2 |
% |
|
1 004 153 |
63 |
214 019 |
13 |
373 280 |
23 |
1 591 452 |
100 |
Tab 8.6.63.a: Cumulative size (km
2) of areas pertaining to each environmental suitability class within the Extent of Occurrence.|
Number Patches (NP) |
Mean Patch Size (MPS) km2 |
Patch Size SD (PSSD) km2 |
Largest Patch Index (LPI) % |
Mean Shape Index (MSI) |
Area-Weighted Mean Shape Index (AWMSI) |
|
|
suitable |
433 |
2 321 |
46 423 |
79.42 |
1.24 |
20.07 |
|
moderately suitable |
1 211 |
176 |
1 380 |
2.75 |
1.25 |
5.32 |
|
Total AO |
362 |
3 364 |
59 218 |
92.57 |
1.3 |
13.68 |
Tab 8.6.63.b: Area of Occupancy fragmentation indexes.
Probabilistic-continuous (PC) distribution model
The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 8.6.63.c
Validation
|
% of EO in sample areas |
Number of valid plots |
Index of Accordance (%) |
|
9.53 |
91 |
64.84 |
Tab 8.6.63.c: Categorical-discrete (CD) distribution model validation parameters.
Comments and conservation issues
The known EO extends from central Kenya to most of former Zaire: however, the western limit of the range should be verified and a large part of the eastern range has been found to be largely unsuitable, especially in Rwanda, Burundi and Tanzania. These, and the following conclusions, are supported by a good Index of Accordance (64.84%). The AO is not very fragmented and the large block of central former Zaire forest certainly accounts for the high LPI (79.42%). About 5% of the AO is included in existing protected areas. The vastity of the range and the lack of knowledge on the actual intensity of hunting and trapping result in a classification of Lower Risk, but further research is needed to confirm it..
|
SUITABILITY CLASS |
inside |
outside |
Total |
|
suitable |
2.51 |
60.59 |
63.10 |
|
moderately suitable |
1 |
12.44 |
13.45 |
|
unsuitable |
2.32 |
21.14 |
23.46 |
|
Total |
5.83 |
94.17 |
100 |
Tab 8.6.63.d: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.
References
East R. (Ed.) (1988). Antelope Global Survey and Regional Action plans, Part I: East and North East Africa. IUCN/SSC Antelope Specialist Group.
East R. (Ed.) (1990). Antelopes Global Survey and Regional Action Plans. Part 3: West and Central Africa. IUCN/SSC Antelope Specialist Group.
East R. (Ed.) (1996). Antelope survey update. IUCN/SSC Antelope Specialist Group: n° 2.
Monfort A. (1992). Première liste commentée des mammifères du Rwanda. Rev. Zool. Africaine: 106(2), 141-151.
Nummelin M. (1990). Relative habitat use of duikers, bush pigs, and elephants in virgin and selectively logged areas of Kebale Forest, Uganda. Tropical Zoology: 3, 111-120.
Wilson D.E., Reeder D.M. (Eds) (1993). Mammal Species of the World: A Taxonomic and Geographic Reference. Second edition. Smithsonian Institution Press, Washington D.C.
Yalden D.W., Largen M.J., Kock D., Hillman J.C. (1996). Catalogue of the mammals of Ethiopia and Eritrea. 7. Revised checklist, zoogeography and conservation. Tropical Zoology: 9, 73-164.