Seed Dispersal by Birds and Bats in Lowland Philippine Forest Successional Area

Background

While seed dispersal by birds and bats can be an important driver of succession, few studies have studied this dynamic in the tropical forests of SE Asia. This study compares the role of bird and bat dispersal in the lowland dipterocarp forest of the Subic Watershed Forest Reserve (SWFR) in Luzon Island, Philippines.

Research goals & methods

Using pairs of day and night traps, we collected seeds during 3 mo of wet season and 3 mo of dry season in a 1.2-ha study site. Bird-dispersed seeds predominated over those dispersed by bats in terms of both seed abundance and number of seed species. The most abundant endozoochorous seed species were significantly biased toward either bird or bat dispersal. Birds and bats appeared to compete more strongly for fruit resources during the dry season than during the wet season, and bats responded more to changes in the seasons than birds did.

Conclusions & takeaways

Analysis indicated that the number of fleshy-fruited trees surrounding the traps had the strongest influence on overall seed distribution, and that the distribution pattern of day-dispersed seeds was affected by more physical factors in the study site than the pattern of night-dispersed seeds were. Given that birds are the more important dispersers in the study site, restoration efforts in SWFR might benefit by focusing on attracting these dispersers into its degraded habitats.