Dear Tweeters,
There have been large flocks of gulls foraging in fields in Skagit County lately. The rains have brought up many earthworms.
On the 26th, I saw an odd gull at Janicki Fields in Sedro-Woolley. It was with a flock of about 200 Glaucous-winged Gulls, including of course some "Olympic Gulls." There was a lone Ring-billed Gull in the flock, plus one adult and one juvenile "Thayer's" Iceland Gull. The most interesting gull was a smallish, pink-legged one that looked very much like a Thayer's Gull, but which had a mantle that was far too dark for me me to call it a Thayer's. Unfortunately, I was just passing by, en route to some errands, and did not have my camera with me.
Burlington has had big flocks, too, mainly on ballfields at the unimaginatively named Skagit River Park. Yesterday, the 28th, there were about 800 gulls on the fields. About 450 were Ring-billed Gulls, 250 Mew Gulls, and the rest Glaucous-winged Gulls and Olympic Gulls. Herring Gulls have been absent on all of my recent gull forays.
I have been looking for the very pale immature gull that showed up at Skagit River Park last February. A similar bird made a brief appearance earlier this season. This bird was almost pure white, and looked a lot like a Glaucous Gull. I had called it a Glaucous Gull when I first found it, but later, after seeing other birders' better photos, decided to leave it as an unidentified Larus. I think that's what it ended up being called on eBird as well, after several other birders saw it and photographed it.
Yesterday, the 28th, there were two pale juvenile gulls with the flock at Skagit River Park. They stayed by a baseball diamond the whole time, even after a dog-walker showed up and scared a lot of the gulls away. Neither of these juveniles was as pale as last winter's bird, but they were both much paler than all of the juvenile Glaucous-winged and Olympic Gulls present, especially on the head. They were big, pink-legged gulls, with big bills. The bills had goodly gones and black tips. This black color blended into the pinkish color of the basal portion of the bill, which led me to believe that these were not pure Glaucous Gulls. There was also more black on the lower mandible than on the upper.
Here is a link to my eBird checklist, with some mediocre photos of the two gulls.
eBird Checklist - 28 Nov 2021 - Burlington - 15 species (+1 other taxa)

I'd love to hear any ideas about the two birds in my photos!

If I had to throw out a guess, Glaucous-winged Gull X Glaucous Gull would seem the most likely--but that would be no more than a guess. In the gull book by Olsen and Larsson, on page 202, there is a photo of a somewhat similar bird, labelled as a "putative hybrid Glaucous Gull X Glaucous-winged Gull." Details of bill coloration are given as evidence to the bird's hybridity.
One more thing--there has been another huge flock of gulls along Old Highway 99 and Dahlstedt Road, just a minute north of the I-5 Cook Road exit. That flock is mostly Mew Gulls, with a few Ring-billed Gulls and a very few Glaucous-winged. Meanwhile, a larger number of Glaucous-winged Gulls seem to be foraging on the fields along Dahlstedt Road, just east of there.
Happy Gull Watching!
Yours truly,
Gary Bletsch 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman11.u.washington.edu/pipermail/tweeters/attachments/20211129/31cd7e2b/attachment.html>