Sighting Record for Utah

Common name:	Vaux's Swift
Scientific name:	Chaetura vauxi
Date:	5/8/2022
Time:	6:30pm
Length of time observed:	20 minutes off and on
Number:	2
Age:	?
Sex:	?
Location:	Willard Bay State Park, Cottonwood campground
County:	Box Elder
Latilong:	41.416813, -112.054050
Elevation:	4220
Distance to bird:	50ft at closest
Optical equipment:	Nikon 10x42 Binoculars
Weather:	Overcast
Light Conditions:	poor
Description: Size of bird:	Small
(Description:) Basic Shape:	streamlined
(Description:) Overall Pattern:	overall soot gray-brown
(Description:) Bill Type:	tiny
(Description:) Field Marks and Identifying Characteristics:	A strong cold front had just passed through with powerful north winds when we arrived at Willard Bay, and the trees were covered in swallows, mostly Violet-green. As we were birding, the winds subsided and all the swallows got up in a massive spiraling cloud of hundreds of swallows. With the shear number of birds I knew there must be some swifts mixed in, and sure enough within a few minutes we spotted one, but it wasn't the White-throat Swift I was looking for, it was tiny and brown. We actually observed the Vaux's 4 different times over 10 minutes, first a lone swift, then 5 minutes later a pair together, then another lone bird and finally another pair. Whether they were all different birds or the same 2 swifts flying around is impossible to know for sure, but there were a ton of birds present. We had direct comparisons with Violet-green Swallows, they were smaller with a very short stout body, short tail and long straight pointed wings, each longer than the body, with a stiff rabid wingbeat. They were all sooty gray-brown, but did have a paler gray throat. I never saw the rump or heard them call (see photos)
Song or call & method of delivery:	None heard
Behavior:	Flying in a large swarm of swallows
Habitat:	Freshwater reservoir nearby, but over grove of tall cottonwoods
Similar species and how were they eliminated:	White-throated Swift: The common expected swift, but larger, bigger than any swallow except Purple Martins. Long body with a long forked tail, long sickle shaped wings. Contrasting black and white plumage with a white throat extending onto the breast and white on the sides of the rump. Very different Black Swift: Much larger, with a longer squared tail and longer wings and body in proportion. All blackish plumage Chimney Swift: Very similar and mostly separated by range, Chimney are exceptional rare west of the front range of the rockies. Chimney also are larger and seem longer bodied and longer winged and darker overall. Vaux's just seem ridiculously tiny and compact with a frantic wingbeat, Chimney seem to keep their cool and fly more leisurely and seem more normal proportioned to me.
Previous experience with this & similar species:	3rd observation of Vaux's in Utah, I've also seen Vaux's in MX,AZ and WA. I've seen several Chimney in TX and many White-throated and Black Swifts in Utah
References consulted:	Memory From photo(s) taken at the time of the sighting
Description from:
Observer:	Bryant Olsen
Observer's address:	84102
Observer's e-mail address:	**
Other observers who independently identified this bird:	John Neil, Charles Hurd and Mitchell Dart were with me
Date prepared:	5/10/22
Additional material:	Photos
Additional comments:	eBird checklist: https://ebird.org/checklist/S109405699