The vireos are a group of small to medium-sized songbirds restricted to the New World. They are typically dull-plumaged and greenish in color, the smaller species resembling wood warblers apart from their heavier bills.
Thirteen species vireos occur in the United States and Canada; of these all but Hutton's Vireo are migratory.
Males of most species are persistent singers. Songs are usually rather simple and monotonous.