Warblers

Warblers are a large and diverse group of small, insectivorous passerine birds commonly referred to by the same name, rather than a single natural lineage. The term historically covered a wide range of small singing birds in the Old World and the Americas, but modern classifications place these species in several families rather than one. In the Americas, the “New World warblers” belong to the family Parulidae. In the Old World, many species previously lumped as warblers are now divided among several families, including Phylloscopidae (leaf warblers), Acrocephalidae (reed and swamp warblers), Locustellidae (grass warblers), and Cisticolidae, among others. The result is a broad, non-monophyletic assemblage united by convergent similarities in size, shape, and insectivorous habits rather than strict genetic relatedness.

Typical warblers are small, often 9–15 centimeters in length, with slim bodies, pointed bills, and plumage that can be greenish, brown, or yellowish. They commonly forage by gleaning insects from foliage or twigs, and many species are skilled at rapid, soft songs that vary by region. Nesting styles vary, but cup-shaped nests placed in shrubs or low trees are common. Many warblers are migratory, breeding in temperate regions and wintering in warmer areas, while others are resident year-round in tropical forests or savannas.

Warblers occupy a wide range of habitats, from woodlands and wetlands to scrubby margins and gardens. They are valued by birdwatchers for their diversity and vocalizations and serve as indicators of habitat quality in many ecosystems.