The Yellow Warbler proper (aestiva group) breeds in the whole of temperate North America as far south as central Mexico in open, often wet, woodland or shrub. It is migratory, wintering in Central and South America. This form is a very rare vagrant to western Europe. It is 11.5 cm long and weighs 9 g. The summer males of this group are greenish above and yellow below, with red breast streaking. The various aestiva group races vary mainly in brightness.