Common breeder in second-growth deciduous and coniferous forest. Variable song, somewhere between CSWA, AMRE and HOWA, is weak but sweet: ‘weeta weeta weechew.’ Flits around lower vegetation, often flycatching and spreading tail, reminiscent of AMRE. Seems to stand horizontally with tail cocked and spread. ID: Slim with long tail that often appears rounded. A beauty with striking color patterns. All birds can instantly be identified by white undertail with broad black tip. Uppertail has white band and yellow rump. All have bright yellow underparts with white vent and that striking tail pattern! Ad ♂ br: bold black necklace, flank streaks, mantle, and mask through eye. Ad ♀ br: similar to ♂ with subdued pattern. Fall birds gray-headed with pale eyering. Streaking on underparts limited or absent. Some (mostly imm ♀) show pale gray necklace that seems out of place. Back mostly green with narrow white wing bars. Older birds and ♂ show more black streaking on underparts and mantle. When overhead, look for long rounded tail and distinctive undertail pattern.