Upperparts dark olive, undersides yellow. Undertail coverts yellow.
Males have prominent black mask extending across eyes and forehead.
Typically found in dense, marshy habitats, but also in brushy fields and second-growth forests. Winters south from the Carolinas into southern Florida west into southern Texas and Mexico through much of the West Indies. Abundant and stable in most regions, though local extirpation has occurred in parts of the South and West due to draining of wetlands and channeling of rivers.