A medium-sized, sooty-black flycatcher. Marked geographic variation: most North American birds have dull wings and a clean white belly, while South American birds have bright white edging on wing feathers and much more limited white on the belly. Typically seen singly or in pairs, usually sitting conspicuously on a low perch. Frequently pumps tail up and down. Often near water; especially tied to fast-flowing, rocky streams in South America.