Sighting Record for Utah

Common name:	Buff-breasted Sandpiper
Scientific name:	[Calidris subruficollis]
Date:	9/24/2023
Time:	11:00
Length of time observed:	Approximately 20 minutes
Number:	1
Age:
Sex:
Location:	Willard Spur WMA
County:	Box Elder
Latilong:
Elevation:
Distance to bird:	Approx. 1500 ft, measured on Google Maps from the road to the far shore
Optical equipment:	Binoculars, scope, Camera
Weather:	Clear
Light Conditions:	Sunny
Description: Size of bird:	Approximately 8 inches, or an inch or two shorter than a Killdeer
(Description:) Basic Shape:	Calidris, with a more up-right posture
(Description:) Overall Pattern:	Buffy/light orange
(Description:) Bill Type:	Short, straight
(Description:) Field Marks and Identifying Characteristics:	(Copied and edited from my eBird checklist comments) First noticed an overall buffy/orangeish bird without a distinctive breast band, pale legs, plain facial features, and slightly shorter in height than nearby Killdeers. My immediate impression was that of Buff-breasted Sandpiper, and seeing a Calidris sp. of this height and shape could really only be a Pectoral Sandpiper, Buff-breasted Sandpiper, or the much rarer Sharp-tailed Sandpiper. The bird briefly began to preen, and struck a unique upright posture that looked great for BBSA, and as it lifted it's wings showed a bright white flash. It flushed about 15 yards south down the shoreline, and showed a complete lack of white on the rump. I noticed this, but didn't take immediate note of the possibly diagnostic nature of that field mark until it was pointed it out to me from the Sibley app, and I realized again that Pectoral Sandpipers show white on the edges of the rump with a dark tip and dark line down the middle of the tail. Pics (albeit from a distance, and heavily cropped) show a Calidris sandpiper with a height and structure in relation to a Killdeer that eliminates all other possibilities besides Pectoral, and at least two of these pictures show the unique facial features and overall cute impression befitting BBSA. (see photos)
Song or call & method of delivery:	None
Behavior:	Foraging
Habitat:	Appropriate for Buff-breasted Sandpiper. Bird remained outside of the water, preferring the mudflats and seemed unwilling to get feet wet. The bird came close to the wetter areas of the mudflats, but never actually stepped in the water, like the surrounding Killdeer seemed willing to do.
Similar species and how were they eliminated:	After having seen likely a hundred Pectoral Sandpipers this season around the Great Salt Lake, I confidently decided against that as a possibility initially just based on the uniqueness of it's GISS, but later due to the lack of the back stripes I've seen on every individual I've encountered this year, as well as a complete lack of the dense streaking and strong border to the breast band expected on a Pectoral Sandpiper. Sharp-tailed Sandpiper would also show such a breast band, in addition to an obvious cap and bold white supercilium. As far as other possible Calidris species, a Baird's Sandpiper might also show a dull breast pattern, but the length of the bill, pale legs, posture, size and shape would quickly eliminate this as a possibility.
Previous experience with this & similar species:	Extensive experience with Pectoral Sandpipers and Baird's Sandpipers as a common migrants around the Salt Lake, none with Buff-breasted Sandpiper, have seen one Sharp-tailed Sandpiper.
References consulted:	Sibley Field Guide, Cornell Lab's Shorebird Identification Course, and several expert/more-knowledge-than-I birders with more extensive experience with BBSA to review field marks, expected behavior, seasonality, and GISS from pictures.
Description from:	Notes taken at the time of the sighting From photo(s) taken at the time of the sighting
Observer:	Quinn Diaz
Observer's address:
Observer's e-mail address:	**
Other observers who independently identified this bird:
Date prepared:	9/25/2023
Additional material:	Photos
Additional comments: