Sighting Record for Utah

Common name:	Western Gull
Scientific name:	Larus occidentalis
Date:	09-13-2016
Time:	5:00pm
Length of time observed:	15 minutes
Number:	1
Age:	Juvenile
Sex:	?
Location:	Lee Kay Ponds
County:	Salt Lake
Latilong:
Elevation:	4250 ft
Distance to bird:	50m
Optical equipment:	Bushnell 20-48X spotting scope
Weather:	Overcast, 70F
Light Conditions:	Good
Description: Size of bird:	Large gull, 25in
(Description:) Basic Shape:	Typical Larus Gull
(Description:) Overall Pattern:	Very dark sooty brown
(Description:) Bill Type:	Fairly large, all black
(Description:) Field Marks and Identifying Characteristics:	What 1st caught my eye was the dark brown sooty color, also notably larger than California Gulls. Had a large black bill with notable gondynale angle, also had a relatively short primary projection past tail, and notable "secondary skirt", as well as a large round head with eye in the center, all this adds up to a juvenile Western Gull. (see photos)
Song or call & method of delivery:	None heard
Behavior:	Swimming in pond, then loafing on an island
Habitat:	Freshwater ponds near a landfill, not far from the Great Salt Lake
Similar species and how were they eliminated:	California Gull: Smaller, with a smaller bill that usually has a pink base at this age, even the darkest juvenile California's are a shade lighter brown with more white checkering in the wing coverts, mantle and nape. Longer wings with longer primary projection and different overall structure. Direct comparison. Herring Gull: Can be similar, but usually paler, often has a pink bill base, different structure with longer primary projection, lacking "skirt", and with a flatter head with more forward eyes. Bill usually smaller but there is overlap. Yellow-footed Gull: always paler and bigger Glaucous-wing Gull- always paler, has pale primaries. Olympic Gull(Western X Glaucous-winged): Usually paler, and primaries not black, should be similar in shade to mantle. Heerman's Gull: Immatures can also be uniformly very dark, but are much smaller and petite, smaller than California Gulls
Previous experience with this & similar species:	Yes, many: adults, immatures and juveniles, also with all of the gulls listed above except Yellow-footed.
References consulted:	Sibley, online photos, memory
Description from:	From photo(s) taken at the time of the sighting
Observer:	Bryant Olsen
Observer's address:	688 East 700 South #105, SLC, UT 84102
Observer's e-mail address:	**
Other observers who independently identified this bird:	none
Date prepared:	09-13-2016
Additional material:	Photos
Additional comments:	Initially seen on 9-9-16, but my view on that day was less than satisfactory, so not positive of ID, however this caused me to do more study on juvenile Western Gulls, when I relocated it on this day, all doubt was eliminated. As far as I can tell, this is the earliest fall record in Utah, by a couple months.