The acoustics of Hawaiian katydids Free

Nine species of katydids endemic to Hawaii were collected from seven of the main islands in the Hawaiian archipelago, and the acoustic signature of their calls were analyzed. Each species was enclosed in an anechoic sound booth and the calls generated by wing stroking were detected with a broadband miniature microphone and recorded with a broadband instrumentation tape recorder. Signature calls were digitized at an effective sample rate of 500 kHz and stored on PC floppy diskettes. Acoustic analysis of the digitized signals included a determination of the time waveform, frequency spectrogram, and time‐amplitude envelope for each wing stroke. Duration of wing strokes varied from approximately 10 to 30 ms, with peak frequency of each click within a wing stroke varying between 18 to 35 kHz. Rate of wing strokes varied between 9 and 70 per second. Most of the species can be separated according to the acoustic features of the calls. Song variations among isolated populations from one of the islands gave indications of a new species that was later verified by cuticular hydrocarbon composition and morphological analyses.