Vaux’s Swift

Identification

Vaux's swift is among the smallest members of the swift family, measuring just 10.7 to 11.2 cm in length with a weight of approximately 18 grams—though northern populations are slightly larger at 11.5 cm. This compact bird features the characteristic cigar-shaped body, crescent-shaped wings, and short bluntly squared-off tail typical of its genus. The head, upperparts, and wings are dusky black, while the underparts, rump, and tail coverts display a greyish-brown tone. The throat is notably paler grey, becoming whitish in birds from northern regions. Males and females are similar in appearance, though juveniles can be distinguished by dusky bases on their throat feathers.

Range & Habitat

Vaux's swift ranges across North America, Central America, and northern South America, with breeding populations extending from southern Alaska and the highlands of southern Mexico through to eastern Panama and northern Venezuela. Northern populations in the United States are migratory, wintering from central Mexico southward through Central America and into South America, while resident breeding birds in the southern portion of the range remain year-round. The species favors old growth coniferous and deciduous forests in highland areas, typically above 700 meters elevation, and requires large hollow trees for successful breeding.

Behaviour & Diet

This is a highly gregarious species, often seen in flocks of 30 or more birds, frequently mixing with other swift species such as white-collared swifts, particularly at weather fronts. Their flight style combines stiff wing-beats with unsteady glides, while their vocalizations are notably more varied than those of related swift species, featuring a mixture of chattering, buzzes, squeaks, and chips. Vaux's swifts feed entirely in flight, capturing flying insects including beetles, wasps, termites, and flying ants over forests, open areas, and towns. They breed in mountain and foothill regions, constructing cup nests from twigs and saliva in dark cavities such as tree holes, cliff crevices, or attics, typically laying three white eggs between March and July.

Best Time & Places to See It

The most famous concentration of Vaux's swifts occurs at Chapman Elementary School in Northwest Portland, Oregon, where North America's largest known roosting population gathers during autumn migration. From mid-August to mid-October, thousands of birds—with estimates ranging from 1,700 to 35,000 in various years—congregate in the evening sky before funneling into the school's brick chimney to roost for the night. This spectacular phenomenon occurs over approximately 30 minutes between sunset and dark, attracting hundreds to thousands of human spectators alongside natural predators including owls, Peregrine falcons, and Cooper's hawks.

Photography Tips

The Chapman Elementary School roost offers an unparalleled opportunity to photograph Vaux's swifts in dramatic numbers and behavior. Arrive well before sunset to capture the birds' swirling flight patterns as they form "living tornados" above the school. The evening light during this period provides excellent photographic conditions, while the silhouettes of thousands of birds against the darkening sky create striking compositional possibilities. A telephoto lens and a fast shutter speed will be necessary to freeze the swift, erratic flight of these agile birds.