PRIMATES

Full screen Primates Id code: amd310

Cercopithecidae
Colobus angolensis

Sclater, 1860

(Eng) Angolan black-and-white colobus

(Fre) Colobe blanc-et-noir d'Angola

Taxonomic notes

The number of taxonomically distinct populations that can be identified within the genus Colobus and their phylogenetic relationships are still under debate (Oates & Trocco, 1983). However, most authors currently agree in considering C. angolensis as a fully distinct species (Oates & Trocco, 1983; Oates, 1996; Wilson & Reeder, 1993).

IUCN threat category

Data Deficient (DD) as C. a. palliatus (Tanzania black-and-white colobus) in Tanzania and as C. a. prigoginei (Prigogine’s black-and-white colobus) in former Zaire, but Vulnerable (VU: criteria B1+2c) as C. a. ruwenzorii (Ruwenzori black-and-white colobus) in Rwanda, Uganda and former Zaire.

Available information

Habitat use and preferences were investigated in the Lomako Forest (former Zaire) by McGraw (1994); the author also supplies some information on the interspecific relationships with coexisting primate species. A description of habitat use is also found in Moreno-Black & Maples (1977) and Maté et al. (1995), who researched the species in the Diani Beach Forest (Kenya) and in the Kikofe-Ikomaloki region (former Zaire) respectively. Information on its feeding habits is reported by Maisels et al. (1994). General information on its ecology and distribution can be found in Kingdon (1997) and Stuart & Stuart (1997). Status, threats, and conservation issues are discussed in Oates (1996) and Struhsaker (1981).

Known extent of occurrence

C. angolensis occurs in north-east Angola, former Zaire, Rwanda, Burundi, northeast Zambia, southeast Kenya, east Tanzania, as shown in Fig. 2.3.33.a, which has derived from three different sources: Estes (1991), Napier & Napier (1970) and Oates & Trocco (1983), and was revised and updated on the basis of information in Oates (1996).

Categorical-discrete (CD) distribution model

This species occurs in montane and lowland forest (Kingdon, 1997; Moreno-Black & Maples, 1977).

Based on these environmental preferences, the following scores were assigned (Fig. 2.3.33.b) (Tab. 2.3.33.a):

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

suitable		moderately suitable		unsuitable		Total
km²	%	km²	%	km²	%	km²	%
1 071 806	37	464 489	16	1 362 422	47	2 898 717	100

Tab 2.3.33.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	793	1 351	35 560	65.37	1.22	21.45
moderately suitable	1 781	259	4 610	12.12	1.25	10.55
Total AO	963	1 592	46 282	93.75	1.22	21.25

Tab 2.3.33.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.33.c.

Validation

% of EO in sample areas	Number of valid plots	Index of Accordance (%)
2.10	46	84.78

Tab 2.3.33.c: Categorical-discrete (CD) distribution model validation parameters.

Comments and conservation issues

Within the large EO, the suitable areas account for only 37% of the total, and the moderately suitable areas only 16%. The range in Angola and the southern third of the range in former Zaire are indicated by the CD model as largely unsuitable. However, the PC model smooths these sharp distinctions into a more articulate mosaic of suitable and unsuitable areas. The range in Tanzania, Uganda, Rwanda and eastern former Zaire, where most of the threatened subspecies are found, is classified as unsuitable. Based on the field work, which includes Uganda, the CD model scores 84.78% accordance between expected and observed species’ presence. Fragmentation is very high even when the total AO is considered (NP = 963) but this seems due mostly to the high number of small fragments found scattered throughout the range outside the main forest patch in central former Zaire. About 5% of the total AO is protected but it will more important to analyse the distribution of the protected areas in the different parts of the range.

SUITABILITY CLASS	inside	outside	Total
suitable	1.42	35.55	36.98
moderately suitable	0.56	15.46	16.02
unsuitable	4.31	42.69	47
Total	6.30	93.70	100

Tab 2.3.33.d: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.

References

Estes R.D. (1991). The Behavior Guide to African Mammals. Including Hoofed Mammals, Carnivores, Primates. The University of California Press.

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

Maisels F., Gautier-Hion A., Gautier J. (1994). Diets of two sympatric colobines in Zaire: More evidence on seedeating in forests on poor soils. Int J. Primatol.: 15(5), 681-701.

Maté C., Escobar M., Colell M. (1995). Preliminary observations on the ecology of forest cercopithecidae in the Kikofe-Ikomaloki region (Ikela, Zaire). Folia Primatol.: 64, 196-200.

McGraw S. (1994). Census, habitat preference and polispecific association of six monkeys in the Lomako Forest, Zaire. Amer. J. Primatol.: 34 (4), 295-308.

Moreno-Black G.S., Maples W.R. (1977). Differential habitat utilization of four Cercopithecidae in a Kenyan forest. Folia Primatol.: 27, 85-107.

Napier J.R., Napier P.H. (Eds) (1970). Old World Monkeys. Evolution, Systematics and Behavior. Academic Press, London and New York.

Oates J.F. (1996). African Primates Status Survey and Conservation Action plan. IUCN/SSC Primate Specialist Group.

Oates J.F., Trocco T.F. (1983). Taxonomy and phylogeny of black-and-white colobus monkeys: inferences from an analysis of loud call variation. Folia Primatol.: 40, 83-113.

Struhsaker T.T. (1981). Forest and primate conservation in East Africa. Afr. J. Ecol.: 19, 99-114.

Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers.

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.