Echolocation constraints of Daubenton’s Bat foraging over water

摘要: Summary 1. Daubenton’s Bats ( Myotis daubentonii) foraging over a stream concentrated their activity calm surfaces, avoiding an adjacent area with small ripples (< 3 cm high). Aerial insects were most abundant the ripples, so insect distribution could not explain why bats avoided this area. 2. The flew low water and always N = 22) directed head forwards, presumably emitting echolocation beam parallel to surface, thus minimizing clutter. At angle of incidence 30° there was significantly more clutter from rippled water. 3. produced ultrasonic noises in form transient pulses at average rate 6·2 per second. In present case, such common enough potentially interfere target detection by bats. Transient echo moving may be principal reason generally avoid turbulent 4. strength potential prey surface source levels bats’ searching signals measured use estimating level bat when it detects prey. (+ 38 dB sound pressure level) about same as extrapolated distance. This suggests that Bat operates very signal-to-noise ratios for near surface.