Chaetura vauxi (J.K.Townsend, 1839)

Taxonomic Information

Vaux's swift (scientific name: Chaetura vauxi (J.K.Townsend, 1839)) is a small swift, even when compared to other species in the Chaetura genus.

Standard Size Measurements

It measures 10.7 to 11.2 cm (4.2 to 4.4 in) in length and weighs around 18 g (0.63 oz).

Geographic Size Variation

Northern populations are slightly larger, reaching 11.5 cm (4.5 in) in length, a difference thought to follow Bergmann's Rule and/or relate to migration requirements.

Body and Limb Morphology

This species has a cigar-shaped body, crescent-shaped wings, and a short, bluntly squared-off tail.

Plumage Coloration (General)

Its head, upperparts, and wings are dusky black, while its underparts, rump, and tail coverts are greyish brown.

Throat Plumage Variation

Its throat is paler grey, turning whitish in northern individuals.

Sexual and Juvenile Plumage Differences

Males and females have similar appearances, but juveniles have dusky bases on their throat feathers.

Breeding Range

Vaux's swift breeds in highland regions ranging from southern Alaska to central California, and from southern Mexico and the northern Yucatán Peninsula to eastern Panama and northern Venezuela.

Migratory Patterns

Populations residing in the United States are migratory, and winter from central Mexico south through the species' Central American breeding range.

Southern Population Taxonomy Note

Resident breeding birds found in the southern part of the overall range are sometimes classified as a separate species: the dusky-backed swift, Chaetura richmondi.

Preferred Habitat and Nesting Requirements

This species' preferred habitat is old growth coniferous or deciduous forests, and it requires large, hollow trees for nesting.