Bioacoustics of Purapurana mindanaoensis

Song ( Figure 14 ) Recordings of the song of this species, totalling several minutes, were obtained at the type locality. The sound is a resonant, stuttering buzz with a bell-like quality, and it contains amplitude and frequency modulation as well as a complex pattern of fundamental pulses, syllables and echemes. The song is arranged into phrases that change in structure as a male continues to sing, progressing from shorter, usually isolated phrases, to longer ones up to ca.2 s often concatenated into sets lasting up to 49s in our limited sample. In its most developed form, a single phrase usually consists of 4–6 repeated echemes, each comprising (1) an initial syllable containing coalesced pulses lasting about 40–80 ms, (2) a shorter syllable containing isolated pulses repeated at about 180/s, and (3) ca. 1–3 higher amplitude syllables lasting 15–50 ms and containing pulses produced at about 360/s. The phrase begins and ends with less well-defined strings of pulses. Complex frequency and amplitude modulation patterns occur, with the loudest syllables having a lower dominant pitch (ca. 6.8 kHz) than the syllables containing coalesced pulses (14.2 kHz), and with the transition occurring during the syllables containing isolated pulses. Frequency modulation is also apparent at a shorter time scale, within individual pulses.