This gem of a warbler is in precipitous decline over much of its range. Distinctive if seen well; note black-and-white face pattern with yellow crown and large yellow patch on wing. Female is a washed-out version of male. Frequently hybridizes with Blue-winged Warbler. Found in shrubby habitats near the edge of taller forest, often close to water. Sings a high-pitched buzzy song usually 3-4 notes with first note highest, but variable; occasionally identical to Blue-winged Warbler but typically higher and finer. Feeds on insects.