Vaux's Swift

Chaetura vauxi

  • Version: 3.0 — Published October 23, 2019
  • Larry Schwitters, Drew Schwitters, Evelyn L. Bull, and Charles T. Collins

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Figure 1. Breeding range and year-round range of Vaux's Swift.

Northern populations are migratory, southern populations generally resident. See text for details.

Vaux's Swift (26 April).

Smallest swift in North America. Upperparts are plain grayish brown, sometimes with a slight green iridescence; the rump and uppertail coverts are slightly paler. Ages and sexes are all similar in appearance.

© Steve Kolbe , California , United States , 26 April 2015
Vaux's Swift (3 May).

Underparts paler than upperparts, the throat and upper breast pale gray becoming whitish with wear in spring (throat paler than rest of undersides), and the underwing lesser coverts dusky gray, darker than rest of underwing surface. Small rounded tail, rectrices tipped with spines for support while perching on vertical surfaces at nesting and roosting sites.

© Joachim Bertrands , California , United States , 3 May 2018

Vaux's Swift, a slightly smaller counterpart of the Chimney Swift (Chaetura pelagica) of eastern North America, breeds from just south of the Yukon through the western United States to Mexico, Central America, with a disputed subspecies in northern Venezuela. During winter months, northern migrant populations of this species overlap southern residents. Best known for its quick flight and dazzling aerial agility, this bird seldom perches except when nesting or roosting, and it probably mates on the wing. Hollow trees and unlined chimneys are its favored nesting and roosting sites, making the Vaux's Swift vulnerable to loss of old-growth forest and aging masonry structures. Indeed, recent declines in Vaux's Swift populations have been documented throughout its range where mature forest is dwindling. Its nest, an open half-circle of loosely woven twigs, is glued together and attached to the inside of a hollow tree or chimney with sticky saliva. In migration, large flocks of this species circle roosts at dusk, feigning entry until the first few birds take the plunge—then the whole flock follows abruptly, literally pouring out of the sky and disappearing into the roost.

Like other swifts, the Vaux's Swift is almost entirely insectivorous—a consumer of aerial plankton—hawking a variety of ants, bugs, flies, moths, spiders, and aphids from the air. An adult feeding young collects boluses of food in its mouth and carries these back to its nestlings. Each parent makes up to 50 trips per day, delivering more than 5,000 small insects from dawn to dusk.

This swift is named for William S. Vaux (1811–1882), a member of the Academy of Natural Sciences of Philadelphia and a friend of John K. Townsend, who described this species in 1839 from specimens collected on the Columbia River.

Many of the life history traits of the Vaux's Swift remain poorly known, although extensive studies in forests of northeastern Oregon have provided information on nest and roost site characteristics (1, 2, 3), diet and foraging activity (4), and nesting chronology (5). Comparative studies in other parts of its range are desirable.

Recommended Citation

Schwitters, L., D. Schwitters, E. L. Bull, and C. T. Collins (2019). Vaux's Swift (Chaetura vauxi), version 3.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.