SEED DISPERSAL BY FOREST CHIMPANZEES IN UGANDA

The role of chimpanzees (Pan troglodytes) as seed dispersers in the Ki bale Forest Reserve of western Uganda was assessed by analysing 1849 d ung samples from two chimpanzee communities and by conducting germinat ion trials on dispersed and non-dispersed seeds. Of the chimpanzee dun g samples, 98.5% contained seeds, and fig seeds were the most common. The number of large seeds (>2 mm) per dung sample was often high, even for species with a relatively large seed. For example, Mimusops bagsh awei has a 15-mm diameter seed and had an average of 26.5 seeds per sa mple. In addition, many seed species were found in the dung repeatedly over several months. Germination trials demonstrated that the species of seed commonly collected from dung were viable. Comparisons of both the rate and success of germination of chimpanzee-dispersed seeds wit h seeds collected directly from the parent trees, showed that gut pass age increased the speed and probability of germination. The number of large seeds dispersed by the chimpanzee population was estimated at 36 9 large seeds km-1 day-1. We suggest that in Kibale, chimpanzees may p lay a more significant role in primary seed dispersal than implied by their low numbers and biomass.