Panacanthus cuspidatus (Bolívar, 1881)

The song structure given here is based on the analysis of a single male, collected in December 1985 at Misahualli, Ecuador, recorded later in Canada with ultrasonic-capable equipment. From another audio-limited field tape recording of a male (not shown), we obtained some additional measures (e.g. carrier frequency and call period). Panacanthus cuspidatus calls were very common in December 1985 in the early night, arising high in the forest canopy beside the Rio Napo.

To the human ear, each call is a pair of short whistlelike notes: musical, each note lasting <1 s and lacking any infra- structure. Notes commonly occurred paired in the field, two given about 0.1 s apart (note period ~0.1 s). Calls occur in groups, two to five calls per group with a call period of about 1.5 s; there is a variable group interval of approxi- mately one call each 17s. Laboratory recordings at 20.7^oC show each note as a sustained 25 ms pulse with an extremely gradual amplitude increment from onset, becoming stable over the final third (Fig. 11A, B). This pulse at its maximum amplitude is composed of evenly sustained complex waves, each with a cusp or subcrest, a pattern indicative of two subequal harmonics (see below).

A slight but consistent upward frequency modulation occurred in this specimen: each pulse began just below 10 kHz and finished at about 12 kHz. The field male sing- ing at 21.8^oC had its major peak between 10.2 and 10.3kHz. Therefore, we consider this species' principal carrier as about 11kHz (Fig.12A). Harmonics, a very strong second with diminishing third and fourth, are read- ily apparent. The second harmonic, being within 10 dB of the fundamental, may prove of biological importance in reception. [1]

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