Population Density and Ranging Pattern of Chimpanzees in Kahuzi-Biega National Park, Zaire: A Comparison with a Sympatric Population of Gorillas

Abstract

A population census of chimpanzees (Pan troglodytes schweinfurthii) was conducted in the original part of Kahuzi-Biega National Park, Zaire. The census provides the first estimate of the density of chimpanzees in montane forests of Equatorial Africa. At least three unit groups of chimpanzees were identified in the census area during the 1990 bamboo season. The estimated density (0.13 chimpanzees/km2) falls within the range of densities in savanna, the driest chimpanzee habitat. The estimated density was far lower than the density of gorillas that sympatrically inhabit this montane forest, even though the two apes have been found at almost equal density in tropical forests in other areas. Chimpanzees were typical forest-dwellers, but gorillas ranged over various types of vegetation, including the open vegetation and the swamp. The low diversity and availability of fruits in the montane forest are responsible for the low density of chimpanzees who are frugivorous in various habitats. At least five out of eight primate species raided crops around the borders of the park. Chimpanzees raided maize and plantain bananas. The hostility of the local people towards these primates has recently become heightened in this area. More international attention is needed to augment conservation activities and to protect these primates from the hazards of human disturbances in this area.