The echolocation of flying insects by bats

When bats are hunting insects they adjust the pattern and tempo, of their high frequency orientation sounds in a way that seems quite appropriate for active echolocation of small moving targets but distinctly unsuited for the passive detection of insects by listening for their flight sounds. (Griffin, 1953; 1958). The most obvious change is a marked rise in the pulse repetition rate just as the bat closes in on its prey. For example, Eptesicus fuscus often emits only four or five pulses per second in straight cruising flight, with silent intervals of 200 milliseconds between them; but during insect pursuit the same bat may shift to a "buzz " in which the pulses are separated by only fiv