I found this gull at the mouth of the Dead River in Marquette, Michigan, early in the afternoon of 9 June 2011. Note the light greater coverts, the very light (bleached) primaries, and the overall light (bleached) appearance of this bird. But it first caught my attention as I was driving by not because of its light hue, but rather because of its large size: I could see at a glance that it was larger than the other gulls (Herring and Ring-billed) on the beach, so I stopped to take a closer look. Here is a shot of the gull—standing next to a Herring Gull—that emphasizes its larger size; here is another; here is a slightly different shot emphasizing the same thing; and here is yet another, this time of the bird as it’s landing, giving decent views of the underside of its wings. Here is a shot that gives a slightly different view of this bird (as well as yet another rough size comparison with a distant Herring Gull). Here is a shot of the bird that emphasizes its parallel upper and lower bill. And here is a shot of the bird “yawning”.

Okay, first the easy stuff. This is obviously one of the four year, white-headed, gulls. I think it’s also pretty clearly coming out of its first cycle molt and starting its second cycle. And the final obvious point is that, as above, it’s quite bleached (which is not uncommon in the big white-headed gulls at this molt stage). But now things get tricky! I think this bird is noticeably larger than the nearby Herring Gulls. But of course, Herring Gull is notoriously variable in size (i.e., this bird is probably within a standard deviation of the mean Herring Gull size, but just barely). Regardless, it is a big bird. And as above, note the light greater coverts, as well as the roughly parallel upper and lower bill.

The easy (as well as the most likely) call is “uber-bleached Herring Gull”. But how does one rule out, say, Herring x Glaucous Gull? Or—dare I even type it?—Herring x Slaty-backed Gull? Please note, I’m not claiming that this is anything other than a bleached Herring Gull. But I’m having a hard time articulating exactly why it’s a Herring Gull.