Dear Tweeters,
There was a goodly flock of gulls at the Allen soccer fields in Skagit County yesterday, Beethoven's presumed birthday. This gull spot is on Chuckanut Drive, across the road from WD Foods, a small grocery store. The way to view the gulls is to park in the little lot next to the fire station on Avon-Allen Road. Yesterday's flock included about 280 Glaucous-winged Gulls, 60 Ring-billed Gulls, 10 Mew Gulls, and one gull that had me puzzled.
After about 15 minutes of scoping, photographing, and head-scratching, I called the bird a California Gull and left the scene. My poor photos are on the following eBird checklist.
eBird Checklist - 16 Dec 2021 - Samish Flats - 10 species

The gull was definitely bigger than any of the Ring-billed Gulls. It would have been far larger than any of the Mew Gulls, but those birds were all on the north edge of the flock. The interesting gull stayed on the southern "shoreline" of a huge puddle, near a pair of soccer goals. At least seven or eight times while I observed this gull, it rushed menacingly toward one or more Ring-billed Gulls that were foraging near it. Each time, it would open its wings. The Ring-bills always backed off. The interesting gull never tried this on any of the Glaucous-winged Gulls. 
The gulls were feeding on earthworms. I saw the interesting gull devour one trophy-sized worm that would have sufficed to bedeck quite a few Ritz crackers.
This gull had a mantle that was considerably darker than those of the Ring-billed Gulls. Its bill was larger than those of the Ring-bills, too, but was besmirched with mud, as were its legs. I could tell, though, that the color peeking through the mud on those legs was definitely not pink, ruling out Thayer's Gull, Herring Gull, and so forth.
I see California Gulls reported in Skagit County in wintertime from time to time, but have always viewed such reports with skepticism. They are next to impossible to find here in winter. In fact, over the past 30 years, I have seen the species in Skagit County a total of 10 times during the months of December, January, and February, and only once before in December, that being the 28th of December 1996. 
That makes the California Gull roughly twice as rare here during that time of year than the Glaucous Gull, by my experience. 
If anyone espies ought in those photos to indicate that this bird was not a California Gull, I'd love to hear about it. Thanks.
Yours truly,
Gary Bletsch
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