Calling song (Figs 18–20). This species is atypical in the genus Myopsalta because it produces slightly different song structures in the day and at dusk. The day calling song contains a set of monotonously repeated phrases. Each phrase begins with a single syllable or doublet (0.006–0.025 s) followed by 1–2 additional syllables or doublets and typically 1–2 macrosyllables (0.035–0.081 s) and then a series of 3–13 (usually 5–10) echemes of 0.056–0.308 s duration separated by short gaps of 0.009–0.040 s (all statistics, n =50 recordings; Figs 18, 19). With the exception of the first few (introductory) phrases, each phrase ends with two shorter echemes 0.036–0.105 s duration, separated by a gap of 0.044–0.091 s. The phrase ends with a final long gap of 0.277 s to 1.071 s. It is expected that the female would respond during the long gap at the end of each phrase, following the second shorter echeme; however this interactions has never been recorded in this species. A characteristic of the song is that the first introductory (macro)syllable(s) are 2–3 times quieter than the series of echemes that follow.
Some variation is evident in the number and duration of macrosyllables within each phrase of the day calling song across the geographical distribution of this species (Fig. 19). In central Queensland, the number of echemes in each phrase is typically fewer (3–5) and their duration is longer (0.250–0.308 s). In southern Queensland and New South Wales, the number of echemes is greater (6–13), with number increasing broadly with latitude, and their duration is also shorter (0.056–0.193 s). Further recordings from areas of southern Queensland closer to the Tropic of Capricorn would be required to determine whether the southern and northern song types overlap or coalesce in structure. Based on current data, M. mackinlayi has the potential to be a cryptic species complex.
Despite the apparent variation in the temporal structure of the day calling song, the calls maintain a relatively even frequency distribution throughout, exhibiting a high amplitude plateau of 9.7–14.1 kHz, occasionally reaching 17.7 kHz.
The dusk calling song is effectively a monotonously repeated varation of the day calling song. It commences with a series of soft syllables or macrosyllables, then builds into a monotonous series of echemes (0.105–0.270 s duration), separated by gaps of 0.021–0.037 s duration (all statistics, n =2 recordings; Fig. 20). The dusk song has been observed in populations from south-east Queensland and New South Wales. Whether populations in central Queensland produce the dusk song remains unknown. [1]