Fishing and echolocation behavior of the greater bulldog bat, Noctilio leporinus, in the field

摘要: When hunting for fish Noctilio leporinus uses several strategies. In high search flight it flies within 20–50 cm of the water surface and emits groups two to four echolocation signals, always containing at least one pure constant frequency (CF) pulse mixed CF-FM consisting a CF component which is followed by frequency-modulated (FM) component. The signals are longest, with an average duration 13.3 ms maximum 17 ms. averages 8.9 ms, FM sweeps 3.9 components have frequencies 52.8–56.2 kHz bandwidth 25.9 kHz. A bat in reacts jumping “pointed dips” spot where has broken surface. As descends shows typical approach pattern all bats decreasing interval. reveals itself temporary echo glints, reflected back from its body disturbance. low N. drops height only 4–10 cm, parallel water, legs extended straight turned slightly downward, feet cocked somewhat above line poised 2–4 this situation long series short pulses 5.6 (CF 3.1 2.6) interval 20 indicating that looking targets range. also makes pointed dips during rapidly snapping into localized or random rake mode, surface, lowers drags claws through relatively lines up 10m. behavior similar flight. This indicates mode not pursuing specific targets, raking statistical fishes. raking, directed rakes patches activity high. Our interpretation detects but prefers concentrate on single fish. absence fish, after flying minutes without any dips, starts make very areas hunted successfully before (memory-directed rake). Hunting caught approximately once every 50–200 passes area.