Migration Info This common species breeds in wooded habitat through most of the United States and western Canada, but its winter range is a relatively small portion of western Mexico and Central America. During winter, Warbling Vireos are usually found foraging in mixed species flocks in undisturbed deciduous forests. This rather narrow habitat preference makes this species particularly vulnerable to declines related to habitat loss in its winter range. Recent trends show spring migration to be occurring later, possibly due to reduction of wintering habitat. Western populations apparently stop in northwestern Mexico to molt before proceeding with northward movement.