Yellow-billed Tit-Tyrant

The yellow-billed tit-tyrant is 10 to 12 cm (3.9 to 4.7 in) long and weighs 6 to 7 g (0.21 to 0.25 oz). The sexes have the same plumage. Adults of the nominate subspecies A. f. flavirostris have a blackish split crest formed by elongated feathers on the sides of the crown. Their forecrown is dusky gray with faint white streaks, the rest of their crown is white, their supercilium is white, and the rest of their face is white with bold black streaks. Their upperparts are medium gray-brown with faint blackish streaks. Voice: The yellow-billed tit-tyrant's dawn song is "a rising trill with stuttered burst afterward: brreeee brr-br-br". Its calls are "a rising-falling, musical trill: brrreeeeuu a rising-falling musical chatter: tur-tur-TEE'TEE'tee-tee-tchip".