Long distance migrant. Winters in S Mexico,Central America and N South America,rare south to NE Ecuador.Migrates at night. Departs breeding grounds mid-August to September;Eastern populations swing west before heading south, avoiding SE USA in a circum-Gulf or trans-Gulf of Mecio route to Central & South America. Rare in Cuba & Jamaica during autumn migration.Central & Western populations pass through Mexico August to October & more abundant on Pacfic slope than on Interior or Caribbean slope, Adults migrate earlier than juveniles, which may be stimulated to depart breeding grounds by declining insect resources.
On return migration, passes through Mexico April to early June;trans-Gulf route unlikely for eastern populations in spring.Arrives on breeding grounds late May to early June.