Chapter 5: Enhanced Sampling of Bat Assemblages: A Field Test on Mount Banahaw, Luzon

Abstract

We used a combination of capture methods—harp traps, a tunnel trap, and mist nets—to sample the bat assemblage at two locations (disturbed lowland forest at 620 m and old-growth montane forest at 1450 m) on Mount Banahaw, Luzon Island, Philippines. We placed harp traps and mist nets on ridges and across trails and streams in ravines. The tunnel trap was placed over streams. Over 13 nights, we captured 300 individuals representing 23 species, including two possibly undescribed rhinolophid species. Seventy percent of all mist net captures were frugivores (family Pteropodidae), 95% of harp trap captures were members of the narrow-space insectivore ensemble (the families Rhinolophidae and Hipposideridae and the vespertilionid Kerivoula whiteheadi), and 89% of all bats captured in the tunnel trap were edge-and-gap insectivores, comprising vespertilionids, excluding the subfamily Kerivoulinae. In the lowland forest location, harp traps set along a ridge captured 10 times as many bats as an equal number of harp-trap-nights in a nearby valley. The rapid accumulation of individuals and species over only 13 nights, and effective sampling of insectivorous bats of the families Rhinolophidae, Hipposideridae, and Vespertilionidae, including several poorly known species, indicate that the methods used in this study may be used successfully to further our knowledge of tropical bat assemblages.