Сулавесский свистун Pachycephala sulfuriventer

A fairly nondescript thick-billed, sparrow-sized songbird. Upperparts are uniform rich brown and underparts whitish, but particularly note the yellow wash to the lower belly and the base of the undertail. Juvenile has a gray head and rufous-tinged plumage. Restricted to forested foothills and mountains on Sulawesi, where pairs often join mixed-species feeding flocks in the understory and subcanopy. Yellow vent makes this species easily identifiable in its limited range. Song starts with three or four introductory whistles, often on the same pitch, and ends with a powerful upslurred whip note: “wi-wi-wi-WHIYIP.”