Oddly Plumaged Olympic Gull

I try to cultivate a genuine interest in gulls each winter, but I struggle to maintain that interest once I begin to be stumped by the vast array of plumages presented by the non-adult birds. I have no problem with identifying the adults and some younger birds for our common Utah gulls and I have been able to identify the adults for some of our less common winter gulls. However, identifying young gulls of the less common species can be tough for me. Throw in some young hybrid species and I really get stumped.

I found myself and another local birder stumped this morning when I stopped by Lee Kay Ponds (5600 W and California Avenue) after spending a few hours catching up on work assignments in my Salt Lake City office. The gull was associating with some young Herring Gulls. This gull's primaries were noticeably paler than those of the Herring Gulls and the head, mantle, chest and sides were showing more of a solid gray rather than brownish checkered pattern. I checked the only field guide I had with me and could not find a young gull to match what I was seeing. I didn't have much time so I decided to capture some images with the idea of referring to them later and sharing them with others to confirm the identity. It was identified as an Olympic Gull (Western x Glaucus-winged hybrid) that had been seen previously at the same location. The name Olympic, by the way, comes from the area in Washington where the breeding ranges for Western and Glaucus-winged Gulls overlap. I decided to share the images with an experienced Washington state birder who confirmed that the bill and wings were a match for Glaucus-winged Gull, but he found the grey color on the head, mantle, chest, and sides to be a bit odd for the gull. I suppose that's what you get when you start mixing species.

Here are images I captured today. A young Herring Gull dropped in on the hybrid as I was capturing the images. The gulls separated after a brief skirmish. The hybrid flew across the water and out of sight.

I'm ready to invest in my first guide to gulls so I'm open to recommendations if you have one. Feel free to share your recommendations and any comments you have on the plumage and identity of this oddly adorned Olympic Gull.