Differences in diet and echolocation in four sympatric bat species and their respective ecological niches

The morphology, diet and echolocation characteristics of four bat species roosting in the same cave were studied in Fangshan District of Beijing from the beginning of May, 2002 to the middle of September, 2003. The four sympatric species were: Rickett's big-footed bat Myotis ricketti, Large mouse-eared bat M. chinensis, Greater horseshoe bat Rhinolophus ferrumequinum and Greater tube-nosed bat Murina leucogaster. M. ricketti, comprising 68.8% of the individuals found in the cave, always foraged on freshwater fishes, such as Zacco platypus(Cyprindidae, Leuciscinae) and two minnows(Carassius auratus and Phoxinus lagowskii). Its brief frequency-modulated(FM) echolocation pulse contained most energy at 41.87±1.07 kHz. R. ferrumequinum preyed mostly on moths(Lepidoptera, Insecta; 73% of volume percentage) and emitted calls with a constant frequency(CF) component around 74.70±0.13 kHz. The dominant prey of M. chinensis consisted of ground-dwelling beetles(65.4%,Carabidae and Silphidae, Coleoptera). It emitted FM calls with a characteristic frequency at 35.73±0.92 kHz. Finally, M. leucogaster used high frequency calls(max. energy around 59.47±1.50 kHz) to detect small aerial beetles(90%) of Cantharoidea and Coccinellidae. These results demonstrated that the four sympatric bat species were highly adapted to different foraging habitats and strategies which is also reflected in the remarkably different, species-specific echolocation calls and morphological characteristics. The present work suggests that the trophic resource partitioning and spatial differences in foraging niches represent the major mechanism for the co-existence of this particular bat community