Nondescript warbler, generally olive overall, but different populations vary from grayer to brighter yellow. Overall very plain, but note darkish line through eye and thin pale eye arcs. Forages for insects in scrubby areas at edges of woods or low, thick shrubs. Bill is more sharply pointed than most other warblers. More common in the western U.S. and Mexico, where populations are brighter yellow-green. Birds in the eastern U.S. are scarcer and drabber gray. Bright yellow undertail coverts help separate it from similarly drab Tennessee Warbler. Winters in southern U.S. through Central America.