Calling song (Figs 9, 10). The song of this species contains simple, repetitive buzzing phrases, each beginning softly then rising sharply to a constant amplitude for the remainder. Each phrase commences with a long echeme of 0.800–6.150 s duration, followed by a brief gap (0.008–0.040 s) and a syllable or macrosyllable of 0.006–0.028 s duration (all statistics, n= 49 recordings). Occasionally, an additional syllable or macrosyllable is produced at the end of the phrase. Each phrase concludes with a gap of 0.021–0.191 s duration. When short gaps occur, the phrases often appear to follow on continuously. In the absence of direct observations, it is presumed that the female would respond with a wing flick during longer gaps at the end of each phrase. Close inspection of the structure within the long echeme at the start of each phrase often reveals that the beginning of this echeme contains a series of discrete syllables, although in some cases these syllables at the beginning of each long echeme may be entirely coalesced. Indeed, there is a progression from isolated short syllables to isolated longer syllables, to coalesced syllables.
The calling song typically exhibits a highest amplitude frequency plateau between 12.0 and 18.6 kHz. There appears to be no dramatic modulation in frequency during production of the calling song. [1]