In the breeding season, the Wilson’s Warbler is largely confined to high, boreal latitudes, from Alaska in the extreme west, to Nova Scotia in the east, and south through the Rockies and the coastal mountains to central California. In winter, the species is found along the Gulf coast of the southern United States, and in Baja California, south over both slopes of Middle America as far as Panama, with a handful of sightings further south. Three subspecies are generally recognized. Chiefly olive-green above and yellow above, the distinctive head pattern of black ‘skull cap’ with yellow supercilium and forehead in males should readily identify the species. Females have a much less obviously dark crown, but also have a well-marked yellow supercilium and forehead patch. During the winter period, Wilson’s Warblers are generally found in wooded and scrubby habitats, but they usually shun dense forests. At all seasons, the species prefers those areas with a particularly dense understory.