Echolocation behavior of the Japanese horseshoe bat in pursuit of fluttering prey
- 512 Downloads
Echolocation sounds of Rhinolophus ferrumequinum nippon as they approached a fluttering moth (Goniocraspidum pryeri) were investigated using an on-board telemetry microphone (Telemike). In 40 % of the successful moth-capture flights, the moth exhibited distinctive evasive flight behavior, but the bat pursued the moth by following its flight path. When the distance to the moth was approximately 3–4 m, the bats increased the duration of the pulses to 65–95 ms, which is 2–3 times longer than those during landing flight (30–40 ms). The mean of 5.8 long pulses were emitted before the final buzz phase of moth capture, without strengthening the sound pressure level. The mean duration of long pulses (79.9 ± 7.9 ms) corresponded to three times the fluttering period of G. pryeri (26.5 × 3 = 79.5 ms). These findings indicate that the bats adjust the pulse duration to increase the number of temporal repetitions of fluttering information rather than to produce more intense sonar sounds to receive fine insect echoes. The bats exhibited Doppler-shift compensation for echoes returning from large static objects ahead, but not for echoes from target moths, even though the bats were focused on capturing the moths. Furthermore, the echoes of the Telemike recordings from target moths showed spectral glints of approximately 1–1.5 kHz caused by the fluttering of the moths but not amplitude glints because of the highly acoustical attenuation of ultrasound in the air, suggesting that spectral information may be more robust than amplitude information in echoes during moth capturing flight.
KeywordsPulse duration Doppler-shift compensation Acoustical glints Rhinolophus ferrumequinum nippon Goniocraspidum pryeri
- Henson DW Jr, Bishop AL, Keating AW, Kobler JB, Henson MM, Wilson BS, Hansen R (1987) Biosonar imaging of insects by Pteronotus p. parnellii, the mustached bat. Natl Geogr Res 3:82–101Google Scholar
- Novick A (1963) Pulse duration in the echolocation of insects by the bats, Pteronotus. Ergebnisse Biol 26:21–26Google Scholar
- Riquimaroux H, Watanabe Y (2000) Characteristics of bat sonar sounds recorded by a telemetry system and a fixed ground microphone. 7th Western Pacific Regional Acoustics conference (WESTPRACVII), pp 233–238Google Scholar
- von der Emde G, Schnitzler HU (1991) Classification of insects by echolocating greater horeseshoe bats. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 167:423–430Google Scholar