Yellow-rumped Antwren

The yellow-rumped antwren is 9.5 to 10.5 cm (3.7 to 4.1 in) long and weighs about 7 to 8 g (0.25 to 0.28 oz). It is a small and slim antwren with a thin bill and a longish tail. The sexes have different plumage. Adult males have a grayish white supercilium and a thin dark line through the eye on an otherwise pale gray face. Their crown and nape are black, their back olive, and their lower back and rump bright yellow with black edges on the back feathers. Their tail is grayish olive. Voice: The yellow-rumped antwren's song is "a series of initially countable notes rising in pitch and shortening in length, and rapidly becoming a high-pitched trill of some 49 notes". Another vocalization is "a rich, sweet tsyu".