The warbling vireo has the largest range of any member of the family in North America, being found from western and southern Canada through most of the United States. They are separated from other vireos by the plain face broken only by a white supercilium, the pale lores, a gray-green back, the lack of wing bars, and the mostly whitish underparts.
Birds in the West average yellower underneath, especially in the fall. Warbling vireos are found in a variety of habitats with deciduous trees including woodlands, riparian areas, and even pastures with scattered sycamores. Even more than most vireos, adults sing from the nest, making them easy to find sometimes.
The song of eastern birds is a jumbled series of fairly rapid whistled notes, reminiscent of the house finch to many ears. Western birds have a slightly buzzier version that is less melodic. Other vocalizations are more rarely heard and include a mew note similar to that given by red-eyed vireo, although it is slightly harsher.
