Greetings all,
Yesterday afternoon the area around Keys Road and Wentzel Slough Road again hosted several large gull flocks. After reading posts regarding the presence of Slaty-backed Gull and possible Slaty-backed Gulls I could not resist the temptation to head to the area and have a look for myself. After all what is more classic NW winter birding than gulls and controversy? Thanks to Charlie, Keith, Matt and others for drawing attention to this group.

I took off from work early and spent from 3:15 to 5:15 working through the flocks. This is a great area for gull study right now. All the regulars are in attendance: Glaucous-Winged (GW) and hybrid GW-Westerns predominated with Mew, Ring-billed, California, Herring, Thayers, Western in a variety of plumage?s. I encountered at least 5 Glaucous Gulls, 3 1st-year birds and 1 each 2nd year and 1 adult. I also believe there are at least 2 and possibly 3 Slaty-backs in this group, though frankly I had a much more difficult time with the paler and smaller (somewhat sleeker) second (or possibly third ?) year bird.

The adult took me quite some time to find, and I did not encounter it until much later in the afternoon. The bird is very dark and just looks to me to be an unquestioned Slaty-back. Interestingly the bird presents a distinctly round head and a rather smallish bill, straight with little depth at the gony?s. I agree with the speculations that this is likely a female. While I have my own description, I won?t recount it here as it is in full agreement with Charlie?s. I though rather I would put forth an account for the third-year bird, which I believe is a good, pure Slaty-back. Let me qualify it first that I have no direct previous experience with 3-yr Slaty-back but have encountered several adults over the years and have looked at a lot of Westerns and hybrids.
The bird Matt photographed and labeled as a presumed 3rd cycle Slaty-back is the bird I focus on below.
Description: A large and heavy gull often presenting a pot-bellied aspect. (Though this aspect is often minimized when extended and feeding as in Matts photos). I also noted a somewhat hunch-backed look when extended, though I don't know that this was at all unique. This is a/the third year bird with a smudgy bill, dark gray-brown tail and some dark brown feathers in the coverts. (Some great photos by the way Matt, thanks for posting).
The bill is rather heavy and is largely dark in the outer ?, and has begun to show some pale or yellowish tones, especially across the top. I find it difficult to get a true feel for the exact shape of the bill on birds like this that are so smudgy. My impression was not as heavy or deep in the gonys as our typical GW, but fairly long. Somewhere between GW and our typical Herring, or perhaps between GW and many or our Glaucous Gulls. Face: clear whitish, yellowish eye surrounded by dark smudging.

Fine streaking on the top of the head, very light down the back of the neck with more dense streaking in the lower hind-neck giving almost a collar when viewed head-on with head down. While this streaking is fairly dense it is not the diffuse, blotchy/blurry streaking of many GW and hybrid birds, but is more well defined and clean.
Mantle color was predominantly gray and quite dark with a few rather un-marked brown feathers. This was distinctly dark gray and cold in tone. It stood out as much darker than the nearby adult "Westerns" (only a couple that I could pick out in this flock, with no light-eyes seen). It is worth noting however that the "pure" adult Westerns that I encountered in this flock seem to be toward the lighter end of the spectrum as many of our NW Westerns are.
The wide white edges of the secondaries show well when standing and in flight, though I have to admit I have little confidence in this feature. One the open wing, the pattern is very nearly full-adult. I obtained brief looks on 4 occasions including a good look at the under wing and all to brief views of the upper-wing. Description as follows. Overall dark gray mantle with black primaries and wide white secondary band. There is a large white mirror on P10 and what appeared to be a somewhat smaller one n P9. I could not see a "string-of-pearls" affect, but likely would not have been able to (if even present) with the views I had. The under wing was gray across the primaries and about what I would expect for and adult Slaty-back.
The pinkish legs seemed deeper and darker in tone than the surrounding birds.
Overall I just had the very strong feel that everything about this bird was right for Slaty-back.
Well, all for now. Good birding.
Bill Shelmerdine
Olympia
Mailto: georn1 at hotmail.com
_________________________________________________________________
Helping your favorite cause is as easy as instant messaging.?You IM, we give.
http://im.live.com/Messenger/IM/Home/?source=text_hotmail_join