Bats and Gaps: Microchiropteran Community Structure in a Queensland Rain Forest

Abstract

We examined how a community of insectivorous bats in upland rain forest differentially used closed canopy areas and artificial gaps produced by selective logging. Bat foraging activity was monitored at paired canopy and gap sites using ultrasonic detection equipment. The data supported the prediction that gap use was related to morphology and bat species were classifiable as closed canopy specialist, gap specialists, and gap incorporators. Closed canopy specialists were species with low aspect ratio and wing loading, whereas gap specialists had high values for these two measures. Gap incorporators, which used both canopy areas and gaps, were intermediate in morphology. The closed canopy species were presumed to forage more readily in a cluttered environment. In this community there were no strict gap specialists, but instead the gap specialists were also recorded in other, more open habitats. The community consisted of two distinct subcommunities: four species in closed canopy areas and five in gaps. Three other species were incorporators, but the incorporation rate was very low; only 8% of the activity in gaps and 27% in closed canopy areas was due to these species. There was no relation between patterns of gap use and gap vegetation cover or age up to 6 yr, suggesting that exclusion of gap specialists from a regenerating gap is a slow process. There is tight phenetic packing in the two subcommunities, indicating that vegetation structure is more important than competition in constraining the structure of this community.