Yellow-bellied Chat-Tyrant

The yellow-bellied chat-tyrant is 12 to 12.5 cm (4.7 to 4.9 in) long. It appears large-headed and has long rictal bristles. The sexes have the same plumage. Adults of the nominate subspecies S. d. diadema have a dark olive crown, blackish lores, and a yellow forecrown that continues as a supercilium that becomes thinner and paler as it extends far past the eye. Their face is otherwise dark olive. Their upperparts are olivaceous to brownish olive. Their wings and tail are dusky. Their throat and belly are light yellow and their breast a more olive-yellow. Voice: The yellow-bellied chat-tyrant's dawn song is "a fast, thin, and delicate little trill that ascends slightly, chiiiiiiii-iiiiiiiit (or prrrreeeeeeeee)"; it has been compared to "fingers running up a comb".