Upperparts of male are bright yellow, with black wings, tail, and forehead, and 2 white wing bars and tail spots. Underparts are bright yellow. Upperparts of female are greenish yellow, with dark wings and tail; underparts are pale yellowish. In winter, the male resembles the female, with brownish underparts, blackish wings, and yellowish face. Female in winter is grayer with brownish wings. The song is a long jumble of warbles, whistles, and twitters. Calls include “per-chick-o-ree” and “sueweeet,” often given during their characteristic undulating flight.