Poster presentation 12th International Mammalogical Congress

Flutter detection by bats using different echolocation strategies (#769)

Ying-Yi Ho 1 , Hsueh-Wen Chang 1
  1. National Sun Yat-sen University, Kaohsiung City, Taiwan

Echolocating bats separate calls and echoes in time using low duty cycle (LDC) echolocation, or in frequency using high duty cycle (HDC) echolocation to avoid self-deafening. HDC echolocation is well suited for detecting fluttering targets (flying insects) in cluttered environments. It is also known that some LDC bats, e.g. Coelops frithii, Muriniae and Kerivoulinae, could detect fluttering targets, although the reason is not clear. In this study, we tested whether the flutter detection of these LDC bats could be explained by the similarity of their call design, and predicted Muriniae/Kerivoulinae, like C. frithii, would detect fluttering target more frequently than other LDC bats. We presented bats a mechanical fluttering target, consisting of a piece of paper (6 x 11 mm) mounted on the 20 cm metal spindle of a 12 V motor, in a flight tent and the field. We recorded sound and flying behaviour from 96 individuals (16 species) in  tents, including (1) C. frithii, (2) Muriniae/Kerivoulinae, (3) other LDC and (4) HDC species. We showed the four groups of bats detected and approached the fluttering target with similar approach rates. In addition to approaching to the fluttering target, some Murina, Kerivoula and Myotis species also attacked the target with the paper removed, indicating these bats detected the prey from cues other than echoes reflected from fluttering wings. Two HDC and five LDC bat species were recorded in the field, and the HDC bat, Rhinolophus monoceros, was recorded most often and showed the highest approach rate of 58%.