Distribution, population density, and status of sympatric cercopithecids in the Campo-Ma'an area, Southwestern Cameroon.

A study on species composition, distribution, and population density of cercopithecids in the Campo-Ma'an area, Southwestern Cameroon, was undertaken from December 1997 until August 2000. A total of 665.5 km of line transects was used for the census. Thirteen diurnal primate species including five endangered species (Gorilla g. gorilla, Pan troglodytes, Mandrillus sphinx, Colobus satanas, Cercocebus torquatus) were recorded in the Campo Forest, the greatest part of which is a logging concession. Cercopithecus nictitans (1.43 groups/km2), C. cephus (1.13 groups/km2), C. pogonias (0.81 groups/km2), and C. torquatus (0.51 groups/km2) occurred at medium frequencies compared to figures from other Central African study sites. Mandrill densities estimated (0.27 groups/km2) show that the area is very important for the conservation of this rare species. Guenon densities found inside areas with a high level of human activities did not differ significantly from densities estimated in areas with a lower level of human activities. C. torquatus densities were significantly higher in the areas with a low level of human disturbance and encounter rates with Lophocebus albigena also indicate a preference of less disturbed areas. Mangabeys are thus likely to be adversely affected by human activities in the area. In the Ma'an Forest, which has not been logged yet, ten species were confirmed. The population densities of two guenons (C. nictitans and C. cephus) were estimated to be twice as high in the unlogged forest area as compared to the logged forest of Campo. Other species are rarer in the Ma'an Forest than in the Campo Forest. Although mangabeys are adversely affected by human activities, the results still indicate that selective logging may be compatible with the conservation of cercopithecids, if a reduced damage logging concept and antipoaching measures are implemented. Increased hunting activities following logging operations will definitely have a negative longterm impact on primate populations in the Campo-Ma'an area if no further, more effective conservation measures will regulate wildlife use in future.