DIET SELECTION AND RESOURCE USE BY FLYING FOXES (GENUSPTEROPUS)

Abstract

Flying foxes of the genus Pteropus (Pteropodidae: Chiroptera) play important roles as pollinators and seed dispersers in oceanic-island forest communities. This research examined general theories of diet breadth, diet selection, and the evolution of feeding strategies in bats in light of information from members of the genus Pteropus that inhabit oceanic islands. The feeding ecology of two species of flying fox, Pteropus samoensis and Pteropus tonganus on the Samoan archipelago, was examined in detail by direct observation and by examining feeding refuse. P. samoensis and P. tonganus fed on over 78 plant species from 39 families throughout their range and on over 69 plant species in Samoa alone. Flying foxes interacted with 59% of the forest tree species in Amalau Valley for fruit or flower resources. Twenty-eight percent of the forest trees were commonly used, and 79% of forest canopy trees were used. Broad overlap in resource use was noted between P. samoensis and P. tonganus with over 22 shared plant species. Seasonal variation in fruit resource use was quantified with a preference index. Flying foxes ate a taxonomically nonrandom subset of fruit species and generally preferred primary forest fruits to those in the secondary forest. Six plant families (Sapotaceae, Mrytaceae, Moraceae, Combretaceae, Fabaceae, and Sapindaceae) were particularly important to flying foxes in Samoa. However, a set of core plant taxa does not exist for Pteropus spp. in Samoa. Differences in the evolution of feeding strategies between mainland fruit-eating chiroptera and island species likely reflect differences in the spatio-temporal availability of resources in the two systems.