Bird Predation and Selection of Different Insects by Great Evening Bats （Ia io)

The diet of the great evening bat, Ia io, was studied in Guizhou province of China in November 2005 and May, July and September 2006. The diet was examined by faecal analysis. Bird feathers were found to comprise most of the great evening bats' faeces in July, September and November. This discovery demonstrates that the great evening bat is a bird-eating bat. In November, bird remains were found comprising 82% (by volume) of the bat faeces, but were not found in May. The food component in May mainly consisted of Coleoptera (85%). In July and September, the proportions of bird feathers and Coleoptera found in the bat faeces were similar (44.6% and 48.7% in July, 51.1% and 43.4% in September, respectively). From May to November, the proportion of bird predation by the great evening bats gradually increased, and the proportion of Coleoptera eaten gradually decreased. Apart from Coleoptera, the great evening bats also preyed on other organisms, including Lepidoptera, Hemiptera, Orthoptera and Hymenoptera. Comparing the food components of bats by faecal analysis with the potential food availability measured in the foraging area, we suggest that the great evening bat is a selective predator