VIREO, the common name of birds of the American passerine family Vireonidae. There are about so species of these insectiv orous birds, which have characteristic and often very musical songs. Twelve species inhabit the United States, all building deep, pendent, cup-shaped nests, usually hung between the forks of a branch. The red-eyed vireo (V. olivaceus) breeds from the Gulf States to Labrador and British Columbia, wintering in Central and South America. West of the Cascade mountains, it
is replaced by Hutton's vireo (V. liuttoni), with three subspecies, lacking the slate crown of V. olivaceus. The warbling vireo (V. gilvus) of eastern U.S.A. and Canada has a fine song.