Mammalian predators can be an important factor to limit the regeneration in tropical forests. To quantify the impact of mammals on the recruitment success of dipterocarps, which dominate SE Asian forests, it is necessary to investigate the effect of forest-level seed and seedling density on successive recruitment after mast fruiting and to identify the important predators. The aim of this study is to quantify the degree of predator saturation under contrasting seed densities (extremely high or low) and to identify the potential predators.

Mast fruiting occurred in 2010 in Deramakot, Sabah, Malaysia. As a consequence of high fruiting intensity, dry mass of the fallen seeds was larger than previous records. To assess the impact of mammalian predation, we conducted the exclusion experiment with cages in primary (high seed density) and secondary (low seed density) forest. In primary forest, predation of seeds and seedlings was <20% among 5 dipterocarp species, whereas >80% in secondary forest. Bearded pig and mouse deer were most frequently observed in camera traps. Previous study did not focus on the impact of mouse deer, but in this forest there is much evidence of predation of browsing animals. These results suggest that when fruiting intensity is extremely high, predator saturation of mammals is common for sympatric dipterocarp species.