Synecology of Bornean primates. I. A test for interspecific interactions in spatial distribution of five species

In a 15-month study of anthropoid primates in the forest of eastern Borneo, observers made 1230 contacts with groups of five different species within a study area of approximately 3 km². A test of the hypothesis that there is no effect on the presence of one species by the presence of another (using the method of partial correlation) shows that in every pair of species the presence of one has a negative effect on the presence of the other, and that in seven of ten pairs the hypothesis may be rejected at the 97% level of confidence or better. Three cases in which the hypothesis cannot be rejected are found to have biological meaning: behavioral data show that niche separation of the pairs of species is such that their distributions should be independent. In spite of widely divergent feeding and locomotor adaptations, it is apparent that the species are competing for use of the forest.