Description wikipedia

The white-winged black tyrant (Knipolegus aterrimus) is a species of bird in the family Tyrannidae, the tyrant flycatchers. It is found in Argentina, Bolivia, Paraguay, Peru, and as a vagrant to Brazil and Chile. The white-winged black tyrant is 16 to 18 cm (6.3 to 7.1 in) long. Adult males of the nominate subspecies are almost entirely shiny black. Their wings have a wide white band on the inner webs of the primaries and secondaries that is very conspicuous in flight but usually hidden when perched. Adult females have a mostly grayish brown head and upperparts with a slightly darker crown, whitish mottling on the face and lores, and a bright cinnamon-rufous rump. Their wings are grayish brown with rufous or whitish edges on the remiges and whitish-buff or cinnamon-buff tips on the coverts that show as two wing bars. Their tail has a bright cinnamon-rufous base; the rest is dark brown with a still darker band across the end. Their underparts are mostly buffy ochraceous that is darkest on the breast and lighter on the throat and belly. Males of subspecies K. a. anthracinus are a duller black than the nominate. Females have less rufous on their tail than the nominate and dusky streaks on the breast. Males of K. a. heterogyna are identical to the nominate. Females have darker upperparts and paler underparts than the nominate. Their wing's markings are much whiter and their rump, uppertail coverts, and tail are a much paler buffy white. Both sexes of all subspecies have a dark brown iris and black legs and feet. Males have a blue-gray bill with a black tip; females have a black bill with a bluish base to the mandible.