Panacanthus intensus

A single male was successfully trans- ported to Canada, caged indoors and recorded at 22 '' C with ultrasonic effective equipment. The shortest time domain element of this species, resolvable by the human ear, is a musical chirp (terminology, Morris et al., 1989), lasting about 300 ms; the chirp has a suggestion of infrastructure. The chirp duty cycle is "1%, being effectively immeasurable: that is, a lone chirp occurred at very long, inconsistent intervals of many minutes to 1h. Calling activity was typically noted after dark, but on one occasion a single call was noted during the day.

The chirp (song) is a train of eighteen pulses, increasing slightly in rate and duration (pulse rate overall 530s''1). Each pulse is a complex wave train of approximately four to five major crests (Fig.11G, H) bearing three or four smaller crests. The song is remarkable for its very high intensity: a call registered 112.9dB (Impulse, hold) as recorded at 10cm with the microphone directed at the dorsal field of the tegmina.

In the frequency domain, the mean dominant peak was 11.7 kHz (average of n 1/4 7 calls, range 11.6-12.5 kHz; Fig. 12D); an apparent second harmonic, about 7 dB below the dominant, occurs near 23 kHz. At about 35 kHz (mean 34.8 kHz, n 1/4 7), is a stronger third harmonic, only 3dB below the dominant. The dominant peak is narrow
(11.7kHz), so that, although the pulse waveform is more complex than that of cuspidatus or pallicornis, the song of this species may still be regarded as relatively high-Q, mainly for its transient nature (Fig. 12).

The high intensity of P. intensus implies that individuals singing in the field may be considerably spaced apart and indeed this species is not as abundant as cloud forest spe- cies. Being so loud is perhaps dangerous, in increasing exposure to acoustically orienting (eavesdropping) preda- tors. Panacanthus intensus may trade-off loudness with a lower duty cycle. Because P. varius and P. lacrimans live in similar lowland habitat (lowlands), they may prove to have similar acoustical behaviour. [1]

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