Bioacoustics of Cacomantis variolosus

Diagnosis: main song of one type , elements consistently and characteristically ‘M’-shaped ( Fig. 2 ) and delivered at moderate pace; basic morph of Australasian morphotype that varies from pale to dark (see 3.2.2(3) above); body medium-sized to large and tail proportionally short to mid-length: wing c. 115–145 mm , tail/wing ratio 0.80– 1.06 ( Table 2 ); barred females with dorsa grading from plain with russet flecking on shoulders in paler populations to dully barred dusky on cinnamon in darker birds, and ventral white barred finely dusky in paler populations to boldly black in darker ones, with light to moderate cinnamon wash; juveniles ranging from dark in tone and clouded in markings to pale, brightly and coarsely patterned (Australian populations). In this group, the acoustic impression of the elements of the main song is dominated by the final deflection ( Fig. 2 ). This is reflected quantitatively in terms of the frequency change between element sections, with significant differences from elements in all other primary differentiates ( Fig. 4 ). Element duration is also generally longer, with some overlap only with Sundaic populations ( Fig. 4 ). This species, known traditionally as the “Brush Cuckoo” throughout Australasia, varies more regionally than any other in the variolosus complex, and has differentiated into 8–9 subspecies, as detailed below (see 4.4.1 following).