Rather nondescript vireo with a blank face. Pale grayish-olive overall with a faint white eyebrow, darker grayish crown, and pale yellowish wash on the sides. Often confused with Philadelphia Vireo; note Warbling shows brightest color on sides (not throat) and fainter dark eyeline (especially indistinct in front of the eye). Warbling is also longer-tailed and has a slightly longer, thinner bill than Philadelphia. Scratchy warbling song is heard from treetops, particularly in riparian areas and cottonwoods. Migrants and wintering birds can be found in any wooded habitat, as far south as Central America.