Bioacoustics of Cacomantis virescens

Diagnosis: main song of one type , elements short and uniquely ‘˄’-shaped ( Fig. 2 ), and delivered faster than in other differentiates except for Philippine sepulcralis ; basic morph of Wallacean morphotype (see 3.2.2(2) above), but darker with mid copper-green dorsal sheen and deep brownish rufous ventral surface, and much reduced white toothing on outer rectrices; body small and tail proportionally very long: wing c. 108–116 mm , tail/wing ratio 1.10– 1.24 ( Table 2 ); barred females with dorsa clearly barred dusky on cinnamon, and ventral white barred clearly black with moderate, if variable, cinnamon wash; juveniles dark in tone and finely marked. In these populations, elements of the main song almost completely lack overlap with other taxa in frequency change from the first to the second portion of the element (when divided into three equal portions; Fig. 4 ). Furthermore, their short element durations and fast song pace overlap significantly only with Moluccan aeruginosus ( Fig. 4 ); as detailed under 4.3 below, the latter has additional, unique vocalizations. Since Stresemann (1912) , this form has been treated as a subspecies of sepulcralis or associated with it because of its rich dark rufous plumage over the entire ventral surface. Eaton et al. (2016) were the first modern source to distinguish it as a species, based on then-unpublished vocal data. Sympatry reported in Sulawesi between virescens and sepulcralis by Inskipp et al . (1996: 47) was not confirmed in the moderately extensive series available to us (n = 47 adults ). The ecology of these two taxa appears to differ, virescens occurring mainly within primary or tall forest ( Heinrich 1932 ; White & Bruce 1986: 234 ; Eaton et al. 2016 ) and sepulcralis in more open habitat, forest edge and wooded copses.