ECHOLOCATION OF FLYING INSECTS BY THE BAT, CHILONYCTERIS PARNELLII

¹ Department of Biology and Department of Engineering and Applied Science, Yale University, New Haven, Connecticut 06520

1. Insect pursuits by C. parnellii can be divided into search, approach, and terminal phases.

2. C. parnellii, using pulses of about 21 msec. in duration, appears to detect insects initially by pulse-echo overlap. This sets the maximum range of detection at about 3.8 m. and presumably requires the use of high intensity pulses.

3. Recognized behavioral changes (increased pulse duration) occur at about 3.3 m.

4. Following detection, pulse duration increases until pulse-echo overlap exceeds 17-8 msec.

5. Pulse-echo overlaps of 18-21 msec. characterize the pursuit from 2.1 to 0.8 m.. after which shortening of pulse duration an closing omnthe imnect sharply reduce pulse-echo overlap to about 7.5 msec. at 0.1 m.

6. Interpulse intervals range from about 20 to 60 msec. during the approach phase but shorten abruptly to about 2.5 msec. in the terminal phase.

7. Several speculative interpretations of the factors controlling pulse repetition rate are discussed. Speculative views of the uses of pulse-echo overlaps of 20 msec. are also discussed.

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