Gorillas and seed dispersal in the Lope Reserve, Gabon. II: Survival and growth of seedlings

Evidence is presented for the importance of western lowland gorillas as seed dispersers in the Lope Reserve, Gabon. The survival and growth of seedlings of three tree species, growing from dung deposited at gorilla nest sites, were monitored for up to 2 y after deposition. A comparison was made between this and seeds (i) deposited in dung on gorilla feeding trails, (ii) dropped (spat out) under conspecific canopies, and (iii) scatter-dispersed (spat out) by other consumers away from conspecific trees but under intact forest canopy. The highest survival and the best performance of seedlings was always at a gorilla nest site, although not every site was favourable for survival or growth. Seedling performance was related to the surrounding vegetation conditions: better performance was observed in seedling clumps with less vegetation cover. Gorillas at Lope apparently provide high quality seed dispersal for these species, not just because they consume large quantities of seeds, but because the pattern of seed deposition, especially in nest sites, can result in the enhanced survival and growth of seedlings.