Niche overlap and polyspecific associations among sympatric cercopithecids in the campo animal reserve, Southwestern Cameroon

Abstract

The community structure and polyspecific associations found in five sympatric resident primates (Cercopithecus nictitans, C. cephus, C. pogonias, Cercocebus torquatus, andC. albigena) and a temporary visitor (Mandrillus sphinx) were studied within the Campo Animal Reserve, a tropical rain forest in southwestern Cameroon. Several ecological variables of the six species, e.g. the number of foraging groups in the study area, group size, home range size, biomass density, and individual density, were estimated by undertaking a systematic census and by other means, e.g. tracing.C. nictitans was the most abundant species in terms of its foraging groups, biomass, and individual densities. The foraging biomass varied significantly among the six species. The five resident species frequently formed polyspecific groups.M. sphinx also associated with them when it visited the area. The food items fed on by the five resident species were also checked. An index for synecological analysis revealed that the five species shared similar food niches. The five species also utilized similar foraging areas and strata, possibly depending on the availabilities of common foods. The above results cannot be explained by conventional equilibrium-competition models. For understanding the polyspecific associations, it is proposed that the primates form polyspecific foraging groups in order to optimize their foraging biomass. This idea leads to a model that can also explain certain of the grouping behaviors, such as group fission-fusion, found in large body size primates.