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Another gull question... this is an interesting one. Seen in Monterey CA today, hanging out with a group of Western Gulls.

Western and Herring can be ruled out because of contrasting pale inner web on outer primaries (visible in 2nd photo). Thayer's can be ruled out by the stout bill, bulky shape (especially head), darker coloration and less distinct patterning overall.

This doesn't strike me as a Glaucous-winged x Western, as they tend to be browner on the head and underparts, with a darker brown "ear muff". 


So I'm thinking Glaucous-winged x Herring Gull hybrid or Slaty-backed Gull on this one. Hoping for Slaty-backed (would be a lifer). Thoughts?




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To me this appears to be a Slaty-backed because like you mentioned it has a lighter ear muff and lighter underparts this is a picture of a hybrid and you can see the difference 


although the last picture appears to be different than the previous birds and better resembles the hybrid but that might be because of the lighting in the particular shot

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I'm beginning to feel better about this being a Slaty-backed Gull, due to a few things - the very thick neck; very full, rotund chest; slightly shorter legs than nearby Western Gulls; relatively slight gonydeal angle, but a fairly stout bill; relatively plain tertials and greater coverts; rather dark grayish scapulars beginning to molt in. However I'm not totally confident about ruling out various Glaucous-winged hybrids.

Here's a picture of a first winter Slaty-backed Gull ffrom the internet. Seems a good match, but not all the pictures I found looked this similar:753133653_slatybackedgull.jpg.32b89353451304c65efbec47442b1547.jpg

Edited by AlexHenry
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  • 4 weeks later...

Here's another gull I observed this winter, this time at Half Moon Bay. The shape and structure of this bird closely resembles that of the bird I posted previously, and is subtly unlike the various gulls that I regularly see in the area. Once again, I am not confident about ruling out Glaucous-winged hybrids, but this bird seems to match the proportions and structure of Slaty-backed Gull. The blocky head shape, the full, rotund chest, rather hunched back, stout-based bill with a relatively insignificant gonydeal angle (compared to Western at least), short legs... am I just over thinking this, or could these be Slaty-backed? This one is still in more juvenile plumage, less molted that the bird I saw previously or the picture I took from the internet. Primaries are noticeably paler.

Hoping for some help here @akiley@akandula@Tony LeukeringDSCN7686.thumb.JPG.4672a2136fdbc1caab14884f865ceff9.JPG

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