Verification of Unusual Sight Record
For Utah

Rec. # 2011-19


Common name:

Vaux's Swift

Scientific name: Chaetura vauxi
Date: May 9, 2011
Time: 1:30 pm
Length of time observed: 2 hrs
Number: 2
Age: Adult
Sex: Unknown
Location: Kaysville Ponds
County: Davis
Latilong: 4101'18.91"N 11156'29.55"W
Elevation: 4317
Distance to bird: Perhaps 100 yards to as close as 20 feet at times
Optical equipment: 8 x 42 binos
Weather: Unseasonably cold, heavy gray clouds, breezy, spitting rain
Light Conditions: Heavy overcast
Description:        Size of bird: Smaller than a swallow
(Description:)       Basic Shape: Curved narrow wings like a boomerang, blunt cylindrical body
(Description:)  Overall Pattern: Dusky dark w/pale upper breast and rump
(Description:)            Bill Type: Couldn't see it
(Description:)                              
Field Marks and
Identifying Characteristics:
Small and very fluttery. Flight pattern was similar to that of the Spotted Sandpiper, i.e. a burst of flapping and then a glide, but upward wing extension was above the horizontal as far as downward wing extension was below horizontal (unlike the Spotty). Not as high/low extension as with any swallow. Wings swept aft significantly, plus narrow base gave the wing silhouettes a boomerang shape. Bodies cylindrical and due to extreme stubbiness of tails, gave the birds a corpulent look. Bodies extended aft of wings only about half the length of any one wing. When birds glided, they held their wings at a downward angle of 15-30 below the horizontal, and they glided a lot.

Color/pattern: Dark, dusky. Upper breast appeared to be a dusky tan color as it contrasted with darker head, underwings and lower breast/tail. Rumps were somewhat pale, not as pale as a Cliff Swallow's, and contrasted with otherwise uniformly dark dusky upper parts.

Heads blunt; could not discern the birds' bills even when they made a pass overhead 20-25 feet away.
Song or call & method of delivery: None heard
Behavior: Flying over a set of municipal ponds where many swallows of six species were also foraging. Swifts did not associate with the swallows, only with each other; one was never far away from the other. Rarely descended to the water's surface as did the swallows. Flew a couple passes low enough against a dark background for observers to see birds in profile view and from behind to assess pale rump plumage. Swifts' altitude over ponds never more than 30-35 yards.
Habitat: Municipal ponds that attract waterfowl, pelicans, cormorants, terns, gulls, shorebirds, kingfishers, blackbirds, and passerine migrants
Similar species and how
were they eliminated:
Not a swallow: No white, rufous or buff on these birds. Silhouette with very narrow, swept back wings and tail extremely short, especially shorter than a Violet-green Swallow's tail. Tail was not notched in any view. Flight pattern different than any swallow present with a fluttery burst of flaps interspersed with long glides with wings held downward persistently at a peculiar angle. Did not touch the water or associate with the swallows. Many swallows landed in willows; swifts did not land.

Black or White-throated Swift: Both Vaux's were smaller than all swallows present; aforementioned swift species are larger than all swallows present and the W-t has striking white markings.

Chimney Swift: Did not detect any calls from review birds even with multiple close passes overhead; Chimney Swifts are chatty birds. Also, Chimney Swifts have relatively larger heads and beaks that might have been more visible than with review birds. Chimney Swifts would likely have compared more favorably in size to the swallows, especially wing length; tail would have been longer although still short in comparison with swallows. Finally, rump plumage appeared pale enough to contrast with otherwise dark upper parts in several views. Observers worked very hard to discern this ID point and saw it several times when at least one bird at a time passed low and then flew against a dark background. Chimney Swifts are more uniformly dark on the upperparts with less or no pale contrast in the rump plumage.
Previous experience with
this & similar species:
Two Vaux's Swifts in 2007 (record 2007-06), many Chimney Swifts in my youth, White-throated Swifts annually, no Black Swifts (yet), all swallows regularly and recently.
References consulted: Sibley
Description from: Notes taken at time of sighting
Observer: Kristin Purdy
Observer's address: Ogden, Utah
Observer's e-mail address: kristinpurdy@comcast.net
Other observers who independently identified this bird: Pomera Fronce
 
Date prepared: May 9, 2011
Additional material:  
Additional_Comments: