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.