Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
PHENOLOGY: Migrates northward, often in small flocks, through North America from mid-March through May. Migrates southward in August and September in large flocks (Stokes 1979). Migrates diurnally (Bent 1940).
ROUTES: A trans-Gulf migrant; the vast majority of individuals apparently cross the Gulf of Mexico between the United States and Mexico. A second migration pathway over the West Indies is apparently little used (Lowery 1943). Raffaele (1989) consider it an extremely rare migrant over the Virgin Islands. Migrates through Costa Rica along the Caribbean coast from mid-March to late April and from early October through early November (Stiles and Skutch 1989). As they migrate through Costa Rica, thousands may gather into feeding flocks over open areas during stormy weather, sometimes in the company of other swifts (Stiles and Skutch 1989).
FLOCK SIZE: A flock migrating over Kingston, Ontario on 14 May 1947 was estimated to contain 10,000 individuals (Bowman 1952). One fall flock, roosting in a hollow Sycamore tree, was estimated to contain 9000 individuals, and another, roosting in a chimney, contained an estimated 12,620 individuals (Bent 1940, Groskin 1945).
MIGRATION SPEED: Travels approximately 100 kilometers per day during migration (Bowman 1952). An individual banded at Kingston, Ontario on 2 September 1928 was recovered 12 days later at Charleston, West Virginia (traveled approximately 62 kilometers per day). Another individual, banded at Lexington, Missouri in September, arrived at Baton Rouge, Louisiana 3 days later (a travel rate of approximately 324 kilometers per day). A swift banded at Baton Rouge, Louisiana was captured 750 kilometers to the north 5 days later (an average of 150 kilometers per day). Another swift banded at Chattanooga, Tennessee was recovered 160 kilometers away on the same day (Bowman 1952). An individual banded at London, Ontario, was captured 12 days later at Knoxville, Tennessee (an average of 67 kilometers per day; Hitchcock 1945). Prior to fall migration, pre-migratory flocks (apparently composed of local individuals) form (Fischer 1958, Michael and Chao 1973).
WINTERING: Winters in the upper Amazon River basin from western Peru to Bolivia and central Brazil (Lincoln 1944, Stiles and Skutch 1989, Terres 1991).