Figure 1. The left top panel (a) shows a spectrogram of a male bellow (spectrogram settings: FFT method; window length 0.05 s; time step = 0.004 s; frequency step = 10 Hz; Gaussian window shape; dynamic range = 35 dB).

Male bellows are characterised by a ‘staccato’ introductory phase that is followed by a continuous series of inhalations and shorter ‘belch-like’ exhalations. The left lower panel (b) illustrates the pulse train structure and clear spectral prominences (labelled F1–F6) of the inhalation phases. The panel on the right (c) shows the typical posture adopted by a bellowing male koala.