Shy warbler of deciduous forest with thick understory. Often found in swampy areas or near slow-moving streams. Bright yellow below with olive back. Telltale black mask set off by yellow spectacles and throat. All plumages show face pattern; adult males boldest with black crown, females and immatures duller with grayish or olive crown. In the breeding season, more often heard than seen. Song is a series of 4-8 loud, rich, rolling notes "preet, preet, preet, preet." Can perch high when singing, otherwise stays near the ground.