The use of tree-fall gaps by a forest interior avian frugivore in a tropical evergreen forest

Previous studies suggest that forest birds commonly use tree-fall gaps owing to the relatively higher availability of fruits and arthropods. However, others have argued that gaps may not be important for food resources but may offer other services, such as increased protection from predators owing to denser vegetation associated with gaps. We examined the use of tree-fall gaps by Puff-throated Bulbul Alophoixus pallidus, an abundant generalist frugivore found in tropical evergreen forests of East Asia. Bulbuls (family Pycnonotidae) are known to be the most important small frugivores in this region (an area with the highest rate of deforestation in the world), and likely to be integral to regional forest maintenance as well as regeneration. This bulbul did not preferentially use small gap interiors (average 163 +/- 43 SE m(2)) and probably avoided them, but it appeared to use areas immediately surrounding gaps more than expected particularly during the breeding season. Such areas probably provide increased security for roosting adults and for young fledglings during the post-fledging period. This first detailed study of the movement of forest bulbuls in tropical East Asia suggests that the use of gaps and gap edges by these frugivores is highly variable in space and time (with equally complex reasons for their use or avoidance) but is likely to impact their role in forest maintenance and restoration.