Bolivian Tyrannulet

The Bolivian tyrannulet is 10 to 12 cm (3.9 to 4.7 in) long and weighs 10 to 11.6 g (0.35 to 0.41 oz). The sexes have the same plumage; females are slightly smaller than males. Adults have a dark olive crown, face, and upperparts. Their wings are mostly dark dusky; the coverts and flight feathers have thin bright yellow-green edges. Their tail is dusky olive. Their throat is whitish, their breast grayish olive to yellowish olive, and their belly and undertail coverts pale yellow. Voice: The Bolivian tyrannulet's dawn song is "a rising, plaintive series of whistles: hee-hee-heEEew" and its call "a mellow descending teew".