Migration Info It is difficult to characterize the migration of this widespread species, because of its extreme geographic variability (there are seven migratory subspecies in North America). The first Yellow Warblers to arrive in the United States are those that reach southern California in mid-March. These birds, representing two subspecies, pass up the Pacific coast and reach southern Alaska by mid-May. The other five subspecies arrive in the United States in early April. This wave of birds passes through the southern states along a broad front stretching from Arizona to Florida. Their movement is rapid; some of these birds will reach the Great Lakes region before the end of April, and others may arrive in interior Alaska by mid-May.