PRIMATES

Primates Id code: amd063

Cercopithecidae
Chlorocebus aethiops

(Linnaeus, 1758)

(Eng) Green, vervet, grivet monkey

(Fre) Vervet, grivet

Taxonomic notes

Placed in Cercopithecus by many authors (Oates, 1996), it is referred to here as a separate genus, in accordance with Wilson & Reeder (1993). This species has often been involved in taxonomic debates, which have split it into as many as four species and 21 subspecies (Oates, 1994). It includes pygerythrus, sabaeus and tantalus, and also djiamdjiamensis (Djam-djam monkey) from the Ethiopian Bale Massif (Wilson & Reeder, 1993).

IUCN threat category

Not listed in the IUCN categories as a species, but considered Data Deficient (DD) as C. a. djiamdjiamensis.

Available information

The ecology of the species has been widely studied. Most of the available information refers to the species in East Africa; little is known on its ecology in Central and West Africa.

East Africa: The main aspects of the species’ ecology were investigated in Lolui Island (Lake Victoria) by Moreno-Black & Maples (1977). In the Amboseli Game Reserve (Kenya), both Lee et al. (1986) and Struhsaker (1967) did research on this species, supplying information on its habitat use and preferences, diet and habits. Lee et al. focused particularly on interactions with humans. A study on habitat use and preferences was conducted in the Diani Beach Forest (Kenya) by Moreno-Black & Maples (1977); the authors also give some information on the species’ spacing patterns and feeding habits. Aspects of the species’ behaviour and population structure and dynamics in Amboseli Game Reserve are analysed in Cheney et al. (1981) and Cheney & Seyfarth (1983, 1986). Interspecific relationships and niche separation among coexisting primates of the Bole Valley (Ethiopia) are discussed in Dunbar & Dunbar (1974). Data on the species’ occurrence and notes on its ecology are available for Ethiopia, Eritrea, and Somalia (Funaioli, 1971; Nievergelt, 1981; Yalden et al., 1977, 1996).

Central and West Africa: The species’ ecology has been poorly studied in this part of its range of distribution. Harrison (1983) investigated the species’ spacing patterns and territorial behaviour in Senegal; information on its habitat use and preferences in old growth and secondary growth forests is reported in Fimbel (1994), who researched on the species at Tiwai (Sierra Leone). Data on the species’ occurrence and notes on its ecology are available for Gabon (Blom et al., 1992), Ghana (Booth, 1979), Comoé National Park (Ivory Coast) (Geerling & Bokdam, 1973), and Kwiambana Game Reserve (Nigeria) (Ajayi et al., 1981).

Southern Africa: The main sources of information on the species’ ecology and distribution are Mills & Hes (1997) and Skinner & Smithers (1990). Population structure in the Mosi-Oa-Tunya National Park (Zambia) is analysed in Tembo (1994). Some data on its density in relation to water availability in the Zambesi woodland (Zimbabwe) are reported in Dunham (1994). Information on the species’ occurrence is available for most of South Africa (Bruton, 1978; De Graaff & Rautenbach, 1983; Lynch, 1983, 1989; Pringle, 1974) and northern Namibia (Viljoen, 1982). Data on the species’ presence in the Sioma-Ngwezi Park (Zambia) are found in Tembo (1995). Most of the authors mentioned above also give some information on the ecology of the species. General information on the species’ ecology and distribution is reported by several authors (Eisenberg et al., 1979; Estes, 1991; Fedigan & Fedigan, 1988; Kingdon, 1997; Lernould, 1988; Struhsaker, 1979; Stuart & Stuart, 1997). Its status and distribution are discussed in Oates (1996).

Known extent of occurrence

The vervet monkey has a wide distribution in Africa, occurring from Senegal to Ethiopia and southwards to South Africa, as well as on the Islands of Zanzibar, Pemba and Mafia (Wilson & Reeder, 1993). Fig. 2.3.24.a was obtained from Kingdon (1997) and revised to match the river network.

Categorical-discrete (CD) distribution model

This species inhabits a wide range of wooded habitat types outside the equatorial rainforest; it occurs in savanna, woodlands and forest/grassland mosaics and it is particular associated to riverine forest throughout the savanna zone. It moves easily into disturbed areas, including farming areas, and can be found in special habitats, such as mangrove swamps (Oates, 1996; Kingdon, 1997; Fedigan & Fedigan, 1988; Skinner & Smithers, 1990; Booth, 1979).

Based on these environmental preferences, the following scores were assigned (Fig. 2.3.24.b) (Tab. 2.3.24.a):

Score
1	Forest mosaics; woodlands; woodland mosaics; other savanna types and croplands occurring inside a 1-km buffer around permanent water.
2	Grasslands, shrublands, bushlands, and croplands occurring outside a 1-km buffer around permanent water; drier forests and mangroves.
3	Deserts and wetter forests.

suitable		moderately suitable		unsuitable		Total
km²	%	km²	%	km²	%	km²	%
10 111 221	73	2 796 265	20	878 601	6	13 786 087	100

Tab 2.3.24.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	1 730	5 865	238 013	76.46	1.27	41.69
moderately suitable	7 945	353	8 216	4.93	1.27	9.63
Total AO	556	23 295	544 956	99.3	1.22	13.71

Tab 2.3.24.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.24.c.

Validation

% of EO in sample areas	Number of valid plots	Index of Accordance (%)
5.80	228	78.51

Tab 2.3.24.c: Categorical-discrete (CD) distribution model validation parameters.

Comments and conservation issues

This is primate species with the largest distribution in Africa, although it may be split into several subspecies. It has very flexible ecological requirements and the overall range appears to be substantially suitable everywhere. Some more arid areas in northern Kenya and Namibia seem to be of lower suitability. The extent to which the species has been studied is reflected in the good performances obtained by the CD model which scores a 78.51% accordance with field work. As for the CD model, the PC model also shows lower suitability areas in Ethiopia, Kenya, Rwanda, Burundi and northern former Zaire. Over such large EO, high NP is expected but the LPI of the suitable areas shows that most (76.46%) of the AO is uninterrupted: the high AWMSI also shows that areas of other suitability classes are deeply interspersed within the AO. Almost 10% of the total AO appears to be included in existing protected areas: however, it could be important to analyse the distribution of these protected areas throughout the range.

SUITABILITY CLASS	inside	outside	Total
suitable	6.65	66.70	73.34
moderately suitable	1.72	18.56	20.28
unsuitable	0.31	6.07	6.37
Total	8.67	91.33	100

Tab 2.3.24.d: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.

References

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