The Warbling Vireo (Vireo gilvus) is a small songbird found throughout most of North America, from Alaska to Mexico. In winter, this species migrates to Mexico and Central America
Adults are mainly olive-grey on the head and upperparts with white underparts; they have brown eyes and the front of the face is light. There is a white stripe just over the eyes. They have thick blue-grey legs and a stout bill. Western birds are generally smaller.
Their preferred breeding habitat is open deciduous and mixed woods where they build their deep cup nest suspended from a tree branch or shrub. The male assists with incubation and may sing from the nest.
They forage for insects in trees, hopping along branches and sometimes hovering. They also eat berries, especially before migration.
Their song is a cheerful warble, similar to that of the Painted Bunting. There are subtle differences in song between eastern and western birds.