Vaux's Swift

The Vaux's Swift is the smallest swift in North America, a compact, fast-flying aerial insectivore closely related to the Chimney Swift. Its body is shaped like a flying cigar, with a short squared tail and long narrow wings that curve backward in a bow shape during flight. It rarely perches in the open, instead using its stiff tail feathers to brace against the inside of hollow trees, snags, and chimneys.

Feathers found beneath a roost site are small and dark. Flight feathers: long, narrow, and tapered with a stiff, slightly curved shaft built for sustained gliding flight. Tail feathers: short and stiff, often showing worn, spine-like tips from constant contact with rough bark or masonry inside roost cavities. Body feathers: short, dense, sooty gray-brown, with a slightly paler grayish throat patch. Compared to the larger Chimney Swift, Vaux's Swift feathers run smaller overall and the throat area is paler and more contrastingly pale against the body.

Sexes look alike. Adults are sooty grayish-brown overall, slightly paler and grayer on the throat and upper breast, with a subtly paler rump in some individuals. Juveniles resemble adults but can show fresher, less worn plumage in late summer. There is no distinct seasonal plumage change; a single annual molt replaces flight feathers gradually, often completed on the wintering grounds in Mexico and Central America.

Vaux's Swifts breed in humid coniferous and mixed forests along the Pacific coast and interior mountains from southeast Alaska to California, favoring areas with old, hollow trees for nesting and roosting. They winter from Mexico south through Central America. During migration, large numbers may gather to roost communally in large hollow trees or industrial chimneys, a spectacle that draws birdwatchers at dusk.

These swifts feed exclusively in flight, sweeping through the air over forests and open areas to catch flying insects. They rarely land except at nest and roost sites, where their short legs and sharp claws allow them to cling to vertical surfaces. Nests are small half-cup structures built from twigs glued together and to the substrate with saliva, placed inside a hollow tree. The flight call is a rapid series of high, twittering chips given in flocks, especially near roost entrances at dusk.