TROPHIC STRUCTURE OF BAT COMMUNITIES IN THE UNDERSTOREY OF LOWLAND DIPTEROCARP RAIN-FOREST IN MALAYSIA

Bat communities in the understorey of primary lowland dipterocarp forest in peninsular Malaysia and Sabah were sampled with mist nets and harp traps to estimate their trophic structure. Overall, 4 of 26 species (15%) at one site, and 6 of 33 species (18%) at the other site were frugivores, while the remainder were insectivores. In terms of individuals, 7-12% of all captures were frugivores. However, the true proportion of frugivores at both sites was probably closer to 1%, because the sampling procedures were strongly biased towards frugivores. In contrast, previously published studies indicate that frugivores comprise 34-48% of species, and up to 80% of individuals in bat communities in the understorey of Neotropical forest. These results support the hypothesis, developed from studies of bird communities, that the understorey of Malaysian dipterocarp forest supports relatively few obligate frugivores, at least in non-masting years. However, further data are required on bats in the canopy, and on the foraging ranges of bats to compare the absolute densities of bats in Malaysian and Neotropical forests.