ARTIODACTYLA

Artiodactyla Id code: amd020

Bovidae
Cephalophus callipygus

Peters, 1876

(Eng) Peters' duiker

(Fre) Céphalophe de Peters

Taxonomic notes

This duiker has been considered conspecific to C. natalensis and/or C. adersi (Wilson & Reeder, 1993). Here, pending a revision of the red duiker group and according to East (1996) and Wilson & Reeder (1993), it is treated as a separate species. It does not include C. weynsi.

IUCN threat category

Lower Risk, near threatened (LR: nt).

Available information

Information available on this species is quite scarce, and no specific studies on its ecology have been conducted. Notes on its habitat use and requirements are found in Gautier-Hion et al. (1980) and Heymans & Lejoly (1981). Feiler (1990) reports on its presence in Angola. Status and distribution in each country in which the species occurs are discussed in East (1988), together with some information on its ecology. General information on the ecology of the species is found in Haltenorth & Diller (1980) and Kingdon (1997).

Known extent of occurrence

The Peters’ duiker is present in southern Cameroon, southern C.A.R., west of the Ubangi-Zaire rivers in Congo and possibly in former Zaire, Eq. Guinea and Gabon (East, 1996; Wilson & Reeder, 1993). The distribution map was first obtained from Haltenorth & Diller (1980), later updated using country map boundaries in East (1988, 1990) as indicated by Dr. R. East (23 June '97) (Fig. 8.6.48.a).

Categorical-discrete (CD) distribution model

This species occurs in primary and secondary lowland and montane forests, where it prefers dense undergrowth. Its absence in riverine strips and gallery forests in the savanna zone is specifically cited (East, 1990; Kingdon, 1997; Heymans & Lejoly, 1981).

Based on these environmental preferences, the following scores were assigned (Fig. 8.6.48.b) (8.6.48.a):

Score
1	Forests.
2	Forest mosaics and transitions.
3	Savannas; croplands.

	suitable		moderately suitable		unsuitable		Total
OCCURRENCE	km²	%	km²	%	km²	%	km²	%
certain	573 246	74	97 393	13	62 046	8	732 685	95
possible	15 879	2	7 860	1	14 342	2	38 081	5
Total	589 125	76	105 253	14	76 388	10	770 766	100

Tab 8.6.48.a: Cumulative size (km2) 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	183	3 206	40 699	79.66	1.37	15.84
moderately suitable	742	143	821	2.66	1.24	3.86
Total AO	45	15 403	98 181	96.14	1.58	10.76

Tab 8.6.48.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 8.6.48.c.

Validation

% of EO in sample areas	Number of valid plots	Index of Accordance (%)
21.91	36	19.44

Tab 8.6.48.c: Categorical-discrete (CD) distribution model validation parameters.

Comments and conservation issues

The Index of Accordance of 19.44%, which is among the lowest in the databank, is probably due both to the low level of knowledge available on the specie and to the identification difficulties encountered during field work. The following comments should thus be taken cautiously. The known EO is mostly suitable, but the separated southern section appears to be of lower suitability and very fragmented. Both models indicate the same lower suitability in this section. With the exception of this part, the EO does not appear to be very fragmented and the suitable areas provide a large continuous patch. The large block of forests of Gabon, Congo and southern Cameroon certainly provides a continuous large distribution area. However, the high AWMSI shows that the shape of the suitable areas (and the total AO) is discontinuous and may indicate significant interspersion with less suitable areas, especially in the western and southern part of the range. About 5.5% of the total AO is included in existing protected areas.

OCCURRENCE	SUITABILITY CLASS	inside	outside	Total
certain	suitable	3.65	70.72	74.37
	moderately suitable	0.76	11.88	12.64
	unsuitable	0.84	7.21	8.05
possible	suitable	0	2.06	2.06
	moderately suitable	0	1.02	1.02
	unsuitable	0	1.86	1.86
Total		5.24	94.76	100

Tab 8.6.48.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.

Feiler A. (1990). Distribution of mammals in Angola and notes on biogeography. Vertebrates in the tropics (Peters, G & R Hutter, eds). Museum Alexander Koenig, Bonn.: 221-236.

Gautier-Hion A., Emmons L.H., Dubost G. (1980). A comparison of the diets of three major groups of primary consumers of Gabon (primates, squirrels and ruminants). Oecologia (Berlin): 45, 182-189.

Haltenorth T., Diller H. (1980). A field guide to the mammals of Africa, including Madagascar. Collins, London.

Heymans J., Lejoly J. (1981). Sur la répartition des Cephalophinae en foret ombrophile. Rev. Zool. Africaine: 95, 1-10.

Kingdon J. (1997). The Kingdon field guide to African Mammals. Academic Press, London and New York: Natural World.

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.