The palm warbler (Setophaga palmarum) is a small North American wood-warbler best known for its distinctive habit of constantly bobbing its tail up and down, a behavior that helps distinguish it from other warblers even at a distance. It breeds in boggy, coniferous forests and open muskegs across Canada and the northern United States, then migrates to spend winters in the southeastern United States, the Caribbean, and Central America, often foraging on the ground in open, grassy areas, fields, and shrubby edges rather than high in trees like many warbler relatives. Breeding-plumaged birds show a chestnut cap, yellow throat and undertail coverts, and a subdued olive-brown back, while winter and immature birds are duller and browner overall but retain the diagnostic yellow undertail coverts and tail-bobbing habit. There are two recognized subspecies—the "yellow" palm warbler of the eastern population, which is more extensively yellow below, and the "western" palm warbler, which is duller and grayer—and both feed primarily on insects during the breeding season, supplementing their diet with berries and seeds in winter.
