Uncommon in W, scarcer to E. Breeds in small deciduous trees with shrubby undergrowth. Tends to stay lower than most other warblers. A tough cookie with small numbers wintering in the cold NE. Found in overgrown field edges and tangles, often its chip note the first sign of presence. Often a loner, seemingly always on the move, invariably in dense tangles, vegetation blocking a clear view. Rarely seen before Sep on fall migration. Song a trill, lower notes at end. ID: Well proportioned with rounded crown and undercarriage. Typical Vermivora bill. Best thought of as a dull yellow bird with very subtle color variation and streaking but essentially uniform with a dark eyeline and supercilium. Head is usually slightly grayer (orange crown almost never visible), diffuse streaks on breast and, most importantly, always yellow undertail coverts. Similar TEWA lacks this uniformity and has white undertail coverts. Slight plumage variation. ♂: brighter than ♀, spring birds brighter than in fall/winter.