Données comparatives sur la socio-écologie de huit espèces de Cercopithecidae vivant dans une même zone de foret primitive périodiquement inondée (nord-est du Gabon)

Eight species of Cercopithecidae were found living in a seasonally flooded forest in N.E. Gabon. Among them, Cercocebus galeritus and Cercopithecus neglectus were strictly restricted to this habitat, whereas Miopithecus talapoin entered the area mostly at dusk to spend the night there. The other five species, Cerco pithecus nictitans, C. pogonias, C. cephus, Cercocebus albigena and Colobus abyssinicus, although primarily rain-forest species, occa sionally entered the flooded forest. The social structure of these monkey groups was very dissi milar : Cercopithecus neglectus lived in small one-male groups of two to six individuals, while Talapoin multi-male troops num bered up to one hundred animals. Cercocebus galeritus were found to form one-male groups of seven to eighteen members, occasionally merging into larger troops. Cercopithecus nictitans, C. pogonias and C. cephus lived also in one-male groups, while Cercocebus albigena were generally observed to form multi-male groups. Some species, such as Cercopithecus cephus, C. nictitans and C. pogonias, were frequently found living together in multispecific troops. Contrary to this, Cercocebus galeritus and Cercopithecus neglectus were seldom found associated together, or with the other sympatric species. Interspecific competition between these last two species of monkeys appears to be strong : both share the same forest layers and have very similar diets. This may explain why they tend to avoid each other, and perhaps also why the density of Cercocebus galeritus is so low. Furthermore, Talapoin monkeys which elsewhere in N.E. Gabon live in the flooded forest when Cercocebus galeritus and Cercopithecus neglectus are absent, were driven away from our observation area by these larger monkeys, and only entered it at dusk for roosting