Dietary partitioning in two gleaning bats, Japanese long-eared bats (Plecotus sacrimontis) and Ussuri tube-nosed bats (Murina ussuriensis): consuming insects of same order but different developmental stages

Abstract

Abstract Knowledge of diet is essential for understanding the mechanism of coexistence among multiple species. Two gleaning bats, the Japanese long-eared bat (Plecotus sacrimontis) and the Ussuri tube-nosed bat (Murina ussuriensis), have similar eco-morphological traits, but it is unclear how they coexist. We examined the seasonal fecal contents of these species in the cool temperate forest of Mount Fuji, central Japan, using microscopical analysis. Long-eared bats, which have larger pinnae, more frequently consumed tympanate insects, such as adult moths, during early spring to summer, whereas tube-nosed bats, which have smaller pinnae, more frequently consumed non-tympanate insects such as caterpillars and grasshoppers, during spring to early summer and summer to autumn, respectively. Interestingly, they consumed insects of the same order but different developmental stages (i.e., adult moths and caterpillars) during spring to early summer, which revelation was made possible by microscopic analysis, not by DNA analysis. These differences suggest that the large pinna of the long-eared bat is an adaptation for preying on tympanate insects, which resulted in food resource partitioning. Additionally, to the best of our knowledge, the Ussuri tube-nosed bat can be considered one of the bats that most frequently eats caterpillars.