Diet of three sympatric insectivorous bat species on Ishigaki Island, Japan

Abstract

We determined the food habits of 3 sympatric species of insectivorous bats (Rhinolophus perditus, Hipposideros turpis and Miniopterus fuscus) from May 2001 to January 2003 on Ishigaki Island, in the Ryukyu archipelago, Japan, by analysing their faecal samples. We also measured wing morphology of these 3 species and assessed insect abundance near the roost. Diet composition dif- fered between the 3 bat species throughout the survey period, except between R. perditus and M. fuscus from July to November 2002. R. perditus mainly consumed Coleoptera, Diptera, Lepidoptera and Hymenoptera, and the proportion of consumption of these insect orders changed seasonally. H. turpis mainly consumed Coleoptera from spring to summer. A large amount of Anomala albopilosa in particular seemed to be consumed. M. fuscus frequently consumed Diptera, Lepidoptera and Hymenoptera throughout the study period and Coleoptera in summer. Our results indicate resource partitioning between each species of bats; this partitioning may be caused by morphological differ- ences between the 3 species of bats, which may result in different passive prey selection. Because of the variation in diet composition, habitats that maintain high insect diversity are required for bat assemblage. In the future, the preferred foraging habitats of the 3 species of bats should be studied, and the results of these studies should be combined with our results for establishing an appropriate conservation measure.