Other Information
SE
Arizona Rare
Bird Alert
(520) 798-1005
Report
Rare Birds
(520) 798-1005
Email
a report
Nature Shop
(520) 629-0510
Agua Caliente Shop
(520) 760-7881
Mason Audubon
Center
(520) 744-0004
Membership
(520) 629-0757
AZ IBA Program
(520) 628-1730
Education Program
(520) 622-2230
Habitat Restoration
(520) 206-9900
Development
(520) 622-5622
Executive Director
(520) 622-5622
|
Birding home | Access updates | RBA | Dastardly Duos | AZ/NM listserv | Tucson area |
Tucson Audubon Society
Dastardly Duos
White-throated Swift and Vaux's Swift
by Larry Liese
Illustrations by George C. West
(Article first appeared in the September, 2002, Vermilion
Flycatcher newsletter. To receive the newsletter in the mail, become a
member of the Friends of Tucson Audubon.)
Birders love to complain about birds whose names just don’t match up with
what recreational birders see when viewing them. This issue’s pair, the White-throated
Swift (Aeronautes saxatalis), and Vaux’s (rhymes with
foxes) Swift (Chaetura vauxi), are two of the approximately 90
species of swifts in the world, and they are swift indeed. Their stiff,
slender wings and tiny legs and feet allow them their great speeds. Many
swifts can achieve speeds over 100 mph. I was once buzzed by White-throated
Swifts atop Picacho Peak and can certainly believe that this is true.
Although these two swifts aren’t all that similar in
their field marks, this is the best time of year to see Vaux’s Swift,
and some of the clues below may help you find one in this year’s fall
migration. Vaux’s Swifts are only seen in southeastern Arizona in April
and May, when rare, and in September and October, when listed as uncommon.
Though much more common in summer, White-throated Swifts are present all
year.
Since swifts do associate with swallows, ruling out a bird being a swallow is necessary. If I believe I’m viewing a swift, I’ve usually first noticed that the leading edge of their pointed wings has a drawn bow shape. From there I go to the tail. Swallow’s tails widen at the ends, distinctly different from our two swifts.
At further distances, shape and flight pattern are your best indicators as to which swift you might be looking at. Vaux’s Swifts are smaller, with shorter wings and much shorter tails. Some swifts’ shapes have been described as "cigars with wings," and the Vaux’s is especially so. White-throated Swifts are longer-tailed with a moderate notch viewable with care. White-throated Swifts tend to fly higher and faster than Vaux’s do, and flap less. They average 50% larger and 70% heavier than the Vaux’s.
When close enough to see well, look for the much more uniform coloration of the Vaux’s. It is a pale gray below, lighter in the throat and upper breast. Since they move so rapidly, it’s hard to observe much further detail on this species. The highly contrasting white areas on the White-throated Swift are easy to see, especially on clear days against a blue sky or dark background. For an added challenge, look also for the white tips to the secondaries and tertials.
Swifts cannot perch horizontally on tree limbs or wires due to their small legs and feet. They roost at night and nest in hidden cavities such as vertical cracks in cliffs and manmade structures (WtS) or hollow trees (VS). This is why they are almost always seen on the wing. I had thought I would be able to expunge the rumor that swifts even sleep on the wing, but it is thought that this does occur in some swift species. Nature can be interesting indeed!
Bird questions? Check Birding | General questions? Contact: Tucson Audubon Society | Webmaster: Email
This page was updated on 02/21/06