vireos

Vireos are a group of small to medium-sized birds in the family Vireonidae. They are passerine birds native to the Americas, with a range spanning from temperate northern regions of North America to tropical South America. The greatest diversity occurs in the tropical forests of Central and South America. Vireos are typically inconspicuous and skulking, with olive or gray upperparts, pale underparts, and a slender, slightly down-curved bill adapted to insect feeding. They are suboscine passerines, a group characterized by less complex vocal development than true songbirds.

Vireos feed mainly on insects, gleaning them from foliage and twigs; some species use short aerial sallies or take fruits, particularly in the non-breeding season. They are often resident in tropical habitats, while several North American species are migratory, wintering in the tropics.

Nesting is generally cup-shaped, well hidden in foliage, built by one or both parents. The clutch usually contains two to four eggs, which are incubated for roughly 12–15 days. Chicks are fed by both parents and fledge after about two weeks.

Taxonomically, the family Vireonidae includes the true vireos along with allied groups such as greenlets and shrike-vireos. The best-known species include the Warbling Vireo (Vireo gilvus), Red-eyed Vireo (Vireo olivaceus), Philadelphia Vireo (Vireo philadelphicus), and Yellow-throated Vireo (Vireo flavifrons). Conservation status varies, but most species are of least concern though forest loss in tropical regions threatens several taxa.