Bird of the Month: White-throated Swift
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
The White-throated Swift is almost always seen in flight where it spends most of its time searching for insects at altitudes up to 13,000 feet.
This cliff-dweller is considered to be the fastest flying bird in North America (Dunn and Alderfer). In flight it will use updrafts and wind to gain speed and still maintain its ability to make quick and erratic changes in direction as it forages for insects (Ryan and Collins).
The White-throated is the only North American swift with white on its plumage and most observers report them along the Columbia River and its tributaries in Washington. At close range, the white throat and stripe down the belly will be clear from below, and if the bird can be viewed from atop a cliff, the white saddlebags and trailing edge of the secondary wing feathers become apparent. However, from a distance, the black and white plumage pattern may not be clear, and the White-throated Swift can be confused with Black Swift, which is larger. The White-throated often migrates with swallows and at times it can be mistaken for a Violet-green Swallow. In both instances, focus on the scimitar shape of the White-throated Swift’s wings and its long, pointed tail will aid in identification.
Vocalizations during flight produce the long, shrill, descending trill, which Pete Dunne of Cape May Observatory describes as one of nature’s most ethereal sounds. Photos and vocalizations, and one slow-motion video of White-throated Swifts entering and exiting a roost site can be found at the Macaulay Library.
HABITAT: OPEN SKY
The White-throated Swift has one of the most appropriate genus names, Aeronautes which means air sailor from the Greek aer, air, and nautes, sailor. Its species epithet saxatalis is from the Latin for living among the rocks, and is equally well-suited to this bird, which spends the terrestrial part of its life on and around rocky cliffs.
The White-throated Swift forages only in flight and feeds on beetles, wasps, bees, leafhoppers, and flying ants. It also mates in flight and an interlocked pair may tumble together for hundreds of feet (Kaufman). Little is known about the nests of White-throated Swifts. They are typically located in very remote and inaccessible niches in rocks. What is known is that the half saucer shaped nest is lined with grass and feathers and attached to a crevice wall by the bird’s saliva. The swifts reuse their nests from year to year and sometimes for decades. For example, a location at the San Juan Capistrano Mission in southern California was used for 26 years, and a site in Birch Creek Canyon in Toiyabe Mountains in Nevada was used for 54 years (Ryan and Collins).
White-throated swift
Scientific Name: Aeronautes saxatalis
Length: 6.5”
Wingspan: 15”
Weight: 1.1 oz (32 g)
AOU Alpha Code: WTSW
STATUS AND DISTRIBUTION
The White-throated Swift is a bird of western North American skies extending from southern British Columbia through the Intermountain West to the mountains of the southwestern United States. They migrate in winter to Mexico and as far south as Honduras. In Washington, White-throated Swifts arrive in April to early May and migrate south in late August.
We lack information about swifts and population estimates are difficult to determine. However, the White-throated Swift appears to be adapting well to the changes in its environment brought about by humans. Since the 1900s these swifts have expanded their range into western cities, finding suitable nest locations in the cracks in older buildings, and freeway bridges and overpasses.
Photo credit: Julio Mulero
References available upon request from amccormick@eastsideaudubon.org
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