[Birdnet] Slaty-backed or Western Gull... out on a limb

[Tim Avery]

So I am going to go out on a limb here to potentially get anyone interested out ot Lee Kay to look for the large dark-mantled gull I found today.  I posted the pics to ID-frontiers and have thus far had people who think the bird is either a Western Gull or as I thought a Slaty-backed Gull.  I have been going over references this evening trying to find simialr looking birds for either species.  Here is waht I have come up with

The bird is a 3rd winter individual.  This is almost a definite, based on the extent of the mantle and wing development.  The mantle was very dark, in the pictures taken on my SLR they came out close to real as being quite "black" looking, whereas the digiscoped images turned out a little light and were not an accurate portrayal of the tone.  There was some smudy feathering in the secondaries, but otehrwise the back and wings appeared fairly solid in coloration.  In flight the bird showed a fairly thick white trailing edge, not as thick as I would expect on Slaty-backed Gull, but I've never seen one, so I'm no expert.    Also, it looked like there were small white tips on p5 and p6.

In the flight shot you can see a fairly black tail, with what looks like white on the outer edges and tips.  This was somethign that the WEGU last winter showed, but may be a bad sign for SBGU, however, I have seen a wide range of tail patterns in teh images I have found.

The head had a little bit of streaking, with quite a bit of streaking and smudging on the nape.

The bill was large and pink at the base, but smudged with black over most of the bill.  

The legs were a deep pink.  

The iris was very pale, almost whitish, which I believe is a good sign for a SBGU but doesn't rule out WEGU.

With that saied it would be nice to knwo what color the orbital ring was, so if you see this bird try and get a look.

Obviously I would love for this to be a Slaty-backed Gull, and that is where I am leaning based off my initial notes and photos, but I would like to be able to eliminate Western Gull (not that having 2 Western Gull present wouldn't be cool).  So thats the info I have on the bird.

Good Birding

Tim
Salt Lake City, Utah
tanager at timaverybirding.com
http://www.timaverybirding.com
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