The aptly named Yellow Warbler is found throughout much of North America in habitats briefly categorized as wet, deciduous thickets. Most resident populations in the Caribbean and in Central and South America breed in mangroves, although at some sites they also occur in coastal scrub or even in montane forests. The Yellow Warbler is the most strikingly yellow among North American wood-warblers. This species displays extensive morphological variation evidenced in the amounts of chestnut streaking on the breast and, in the more southern populations, with variable amounts of chestnut on the head. The breast streaking usually is more prominent in adult males and less so in females and young. The various subspecies of the Yellow Warbler have been arranged usually into three groups mainly based on the color of the head in adult males. Each of these groups has been recognized in the past as a distinct species: Yellow Warbler (aestiva group), which are yellow-headed, migratory forms breeding in North America (United States and Canada); Golden Warbler (petechia group), which largely are chestnut-capped, resident forms in the West Indies; and Mangrove Warbler (erithachorides group), which are chestnut-hooded, resident forms of coastal Middle and northern South America.