ARTIODACTYLA

Artiodactyla Id code: amd055

Bovidae
Cephalophus nigrifrons

Gray, 1871

(Eng) Black-fronted duiker

(Fre) Céphalophe à front noir

Taxonomic notes

It does not include C. rubidus regarded here as a distinct species (Wilson & Reeder, 1993).

IUCN threat category

Lower Risk, near threatened (LR: nt).

Available information

No specific studies on the ecology of the species have been conducted, and literature available is poor. The species' presence has been surveyed in the Kisangani region by Heymans & Lejoly (1981) and in lake Kivu by Rahm & Christiansen (1966), both in former Zaire. Haymans & Lejoly (1981) also give some information on its habitat and estimate the population density in the area surveyed. Data on the presence of the species in Angola are found in Feiler (1990). Gautier-Hion et al. (1980) give some information on the ecology of the species, particularly habitat and diet, and discuss its coexistence with other primary consumers in the Makoku area (north-eastern Gabon). General information on the species' ecology and distribution are found in Kingdon (1997). Status and distribution are analysed in East (1988, 1990); the author also gives valuable information on its habitat use and requirements.

Known extent of occurrence

The black-fronted duiker occurs from Cameroon to former Zaire, Rwanda and west Uganda, and southwards to north Angola. Its presence has also been confirmed from Mt. Elgon (across Uganda and Kenya) and along the Aberdare range and Mt. Kenya in Kenya (Wilson & Reeder, 1993; East, 1996). A first rough map was acquired from Haltenorth & Diller (1980), then updated using specific country maps in East (1988, 1990) and according to Dr. R. East’s personal suggestions (23 June '97) (Fig. 8.6.57.a).

Categorical-discrete (CD) distribution model

This species has adapted to forest, swamp forest and marshes at both low and high altitude; it is sometimes found in gallery forest. (Kingdon, 1997; Rahm & Christiaensen, 1966; East, 1988, 1990).

Based on these environmental preferences, the following scores were assigned (Fig. 8.6.57.b) (8.6.57.a):

Score
1	Forests.
2	Forest mosaics and vegetation types occurring inside a 1-km buffer around permanent water within the forest mosaic and transition zone.
3	Savanna and cropland.
		suitable		moderately suitable		unsuitable		Total
OCCURRENCE		km²	%	km²	%	km²	%	km²	%
certain		1 619 651	60	456 764	17	274 965	10	2 351 380	87
possible		20 366	1	155 839	6	164 298	6	340 503	13
Total		1 640 017	61	612 603	23	439 263	16	2 691 883	100

Tab 8.6.57.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	929	1 830	53 543	69.31	1.22	29.29
moderately suitable	2254	291	5 115	9.73	1.31	13.08
Total AO	271	8 694	138 269	96.79	1.46	25.5

Tab 8.6.57.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 8.6.57.c.

Validation

% of EO in sample area	Number of valid plots	Index of Accordance (%)
5.97	71	71.83

Tab 8.6.57.c: Categorical-discrete (CD) distribution model validation parameters.

Comments and conservation issues

The large EO includes all the forests of central Africa, although it rather abruptly excludes southern Congo. The CD model, which is supported by the Index of Accordance (71.83%), and the PC model to a lesser extent, confirm the lower quality of this part of the range, as well as that of the more eastern areas (Rwanda, Burundi, eastern former Zaire). The part of range of "possible presence" adds very little to the overall distribution range and does not seem to be significantly suitable. Suitable and moderately suitable areas account for more than 77% of the total EO; suitable areas, however, are not very fragmented and the LPI confirms that a large uninterrupted block is available. When the moderately suitable areas are also taken into account, the entire AO becomes almost one continuous patch. Less than 5% of the total AO is included in existing protected areas.

OCCURRENCE	SUITABILITY CLASS	inside	outside	Total
certain	suitable	2.40	57.77	60.17
	moderately suitable	0.86	16.11	16.97
	unsuitable	0.81	9.41	10.21
possible	suitable	0	0.76	0.76
	moderately suitable	0	5.79	5.79
	unsuitable	0	6.10	6.10
Total		4.06	95.94	100

Tab 8.6.57.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.

Rahm U., Christiaensen A. (1966). Les mammiferès de l'Ile Idjwi (Lac Kivu, Congo). Les mammifères de la foret equatoriale de l'est du Congo. Ann. Mus. Roy. Afr. Cent.: n° 149.

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.