Guide to North American Birds
Conservation status Populations are known to be declining in Oregon and Washington, probably elsewhere. Major threat is loss of nesting sites from cutting of large and mature trees.
Family Swifts
Habitat Open sky over forest, lakes, and rivers. Often feeds low over water, especially in morning and evening or during unsettled weather. Nests in coniferous and mixed forest, mainly old-growth forest, including redwood, Douglas-fir, grand fir. Resident subspecies in the American tropics occur in other habitats; in the Yucatan Peninsula, may nest in wells around Mayan ruins.
A small, dark aerialist of the west, often overlooked as it flight high over northwestern forests or low over lakes and rivers with stiff, rapid wingbeats. Similar to the well-known Chimney Swift of the east, but only occasionally nests in chimneys. Because of its reliance on large hollow trees for nest sites, it has become scarce as old-growth forest in the northwest has been destroyed.

Feeding Behavior

Forages in rapid flight, pursuing flying insects and capturing them in wide bill. May forage singly or in flocks. Spiders and sedentary insects in diet may have been captured after being carried high by air currents, or taken from trees by the swifts while hovering briefly in flight.


Eggs

6, sometimes 3-7. White. Incubation is by both sexes, 18-19 days. Young: Both parents care for and feed young. At some nests, one or two additional adults may help parents incubate eggs and feed nestlings. Feeding visits to nest are frequent: average once every 12-18 minutes, perhaps less often as young get older. Young capable of flight at 28-32 days, may return to roost at nest site for several nights after fledging. One brood per year.


Young

Both parents care for and feed young. At some nests, one or two additional adults may help parents incubate eggs and feed nestlings. Feeding visits to nest are frequent: average once every 12-18 minutes, perhaps less often as young get older. Young capable of flight at 28-32 days, may return to roost at nest site for several nights after fledging. One brood per year.

Diet

Mostly flying insects. Feeds on a wide variety of flying insects, including flies, winged ants, bees, moths, beetles, mayflies, and others. Also some spiders and flightless insects.


Nesting

May nest as solitary pairs or in colonies. Courtship involves much aerial chasing, sometimes gliding with wings up in sharp V. Nest site is usually inside hollow tree, reached via broken-off top or woodpecker hole. Sometimes nests in chimneys. Both sexes gather nest material by breaking off small twigs from trees while flying. Twigs are carried in mouth to nest site, cemented into place with sticky saliva. Nest is a shallow half cup glued to inside wall of tree.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Migrates by day. North American breeders move south in fall, probably most to Mexico. Small numbers may winter along California coast, others may move southeast to Gulf of Mexico. Populations in tropical America may be permanent residents.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon

See a fully interactive migration map for this species on the Bird Migration Explorer.

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Songs and Calls

A bat-like chipping. Usually silent on migration.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Vaux's Swift

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.

Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.

Climate Threats Near You
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Climate threats facing the Vaux's Swift

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.