Yellow-bearded Greenbul (Criniger olivaceus) [XC156718]
by Sander Bot from Ankasa Game Reserve, Ghana (song)
Yellow-bearded Greenbul (Criniger olivaceus) [XC525277]
by Peter Boesman from Ankasa NR, Ghana (song)
Subspecies
No subspecies.
Yellow-bearded Bulbul (Criniger olivaceus) and White-bearded Greenbul (Criniger ndussumensis) (Sibley and Monroe 1990, 1993) are retained as separate species contra Dowsett and Forbes-Watson (1993) who include ndussumensis as a subspecies of Yellow-bearded Bulbul (Criniger olivaceus).
Considered by some authors to form a superspecies with White-bearded Greenbul (Criniger ndussumensis) and others them as conspecific, on basis of vocal and behavioural similarities (responds to playback of song of that species). Considerable differences in coloration suggest that, although unquestionably closely related, the two are better treated as distinct species. This supported by results of recent molecular studies, which even suggest that present species is sister-taxon of Red-tailed Bulbul (Criniger calurus), rather than of White-bearded Greenbul (Criniger ndussumensis).
Similar Species
Bearded Bulbul (Criniger barbatus) which is smaller and has green, not greyish-brown, underparts, and less puffy throat.
References
See References.