Abstract
Preliminary results of an extensive survey on the diurnal primate fauna in south-western Congo are reported. The survey was carried out in Region de Niari and Lékoumou from November, 1992 to December, 1992. I confirmed the presence of Pan troglodytes troglodytes and Cercopithecus pogonias by direct observations and the presence of Gorilla gorilla gorilla, Mandrillus sphinx, Cercopithecus cephus and C. nictitans by indirect evidences. Local people informed the presence of Colobus satanus, Cercocebus torquatus, C. albigena and Miopithecus talapoin, but I could not confirm them myself. Population densities of Pan t. troglodytes in the area were caluculated from nest counts. The population densities were higher in the areas near the border of Gabon and in the eastern part of Region de Lékoumou than the other areas. The differences in the population densities in each area seemed to be related with differences in hunting pressure. Average population density in the study areas was far lower than that in Ndoki Forest in the northern part of Congo, but allmost equal to throughout Gabon or in the part of Equatorial Guinea.
