PRIMATES

Full screen Primates Id code: amd356

Cercopithecidae
Colobus vellerosus

(Wesmael, 1835)

(Eng) White-thighed black-and-white colobus

(Fre) Colobe de Geoffroy

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). In accordance with Oates & Trocco (1983) and Oates (1996), C. vellerosus is treated here as a full species, while Wilson & Reeder (1993) include it in C. polykomos.

IUCN threat category

Vulnerable (VU: criteria A1c+2c).

Available information

Literature available on the ecology of this species is very scarce. Some information can be found in Kingdon (1997) and Stuart & Stuart (1997). Ecology, status, distribution, and threats are analysed in Oates (1996).

Known extent of occurrence

This species ranges in west Africa from Ivory Coast (east of the Bandama River) to west Nigeria (2.3.37.a). A first rough distribution map was derived from Oates & Trocco (1983), but it was later revised and updated to match the river network and other reliable distribution maps (Oates, 1996; Kingdon, 1997). However the map should not be taken to reflect this monkey’s present distribution accurately; further information is required.

Categorical-discrete (CD) distribution model

This species occurs primarily in lowland rainforests and gallery forests (Kingdon, 1997).

Based on these environmental preferences, the following scores were assigned (Fig. 2.3.37.b) (Tab. 2.3.37.a):

Score (*)
1	Forests.
2	Forest mosaics.
3	Savannas and croplands.
(*) Scores increased for vegetation types occurring inside a 1-km buffer around permanent water.

suitable		moderately suitable		unsuitable		Total
km²	%	km²	%	km²	%	km²	%
91 370	19	147 515	30	247 538	51	486 423	100

Tab 2.3.37.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	270	341	3 570	24.19	1.3	12.51
moderately suitable	615	239	1 230	9.85	1.51	6.42
Total AO	318	752	10 343	77.19	1.56	14.95

Tab 2.3.37.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.37.c.

Validation

No occurrence of the species within the four sample areas.

Comments and conservation issues

The known EO of this species is the continuation of the EO of Colobus polykomos east of the Bandama River in Ivory Coast. The habitat quality, however, appears far lower than for the western species, and only 19% of the EO is classified as suitable. Together with the moderately suitable areas, the total AO accounts for only half of the EO. Forests and forest mosaics are much more fragmented and smaller here than in the more western coastal states. For this reason the PC model incorrectly classifies the suitability of the AO at a generally higher level: in fact, the PC model considers (and computes) the suitability sampled throughout the EO. The LPI of the suitable areas is low (24.19%) and the contribution of the moderately suitable areas to the continuity of the range appears obvious from the very high LPI of the total AO. The AWMSI (14.95) confirms that the two classes of areas are also strongly interspersed with unsuitable areas. Less than 5% of the total AO is included in existing protected areas, too small a percentage to ensure the conservation of the species.

SUITABILITY CLASS	inside	outside	Total
suitable	0.26	18.52	18.78
moderately suitable	1.97	28.35	30.33
unsuitable	5.66	45.23	50.89
Total	7.89	92.11	100

Tab 2.3.37.c: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.

References

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

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.

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.