Population Densities and Patterns of Habitat Use Among Anthropoid Primates of the Ituri Forest, Zaire

Abstract

The Ituri Forest of Eastern Zaire contains the richest recorded assemblage of anthropoid primates in the world (13 sympatric species), the behavior and ecology of which have not previously been studied. This study reports the result of line transect censuses at seven locations in the northern and central Ituri, and presents analyses of primate habitat use according to forest type, treefall gaps, tree species in which primates were observed, and height of primates in the vegetation. Estimated total anthropoid primate density is 112 ind/km2, corresponding to a biomass of 715 kg/ km2. Three common species of frugivorous/insectivorous Cercopithecus monkeys (C. ascanius, C. mitis, C. pogonius) showed pronounced habitat preferences for secondary forest, as did one folivore, Colobus guereza. The two more abundant colobine monkeys (Colobus angolensis and C. badius) were seen mainly in mature mixed forest. Very few primates of any species were observed in areas of mbau forest, a forest type dominated by the single tree species Gilbertiodendron dewevrei. The smallest Cercopithecus monkey, C. ascanius, was frequently observed in and around treefall gaps, and may be a gap-specialist in this species-rich primate community. The abundance of common Cercopithecus monkeys in secondary forest may be a response to continuous fruiting of pioneer tree species which constitute a dependable but low-quality resource during the seasonal hiatus of fruit availability in primary forest.