OK, so another ultra-birder pro extraordinaire has weighed in. Blair Nikula also answered my desperate email plea for guidance, and wrote:
“Well, I agree it’s a large gull of some sort, but I don’t think I would venture beyond that! At least not based upon just the photos. I think the bird is more likely to be extremely bleached rather than leucistic.
(I’ve never seen a gull, leucistic or otherwise, that had white legs.) The bill shape would argue against Iceland, but is consistent with Herring. And, of course, the odds heavily favor Herring as well.
That’s my two cents worth.”
The only issue is that this bird was reasonably fresh, and could not have been dead on the beach all that long in the heat of the summer. Thus, there could not have been all that much time for the carcass to bleach out. What’s more, we don’t typically see this degree of leg bleaching even in very decomposed carcasses that have sat out for some months. Very mysterious. Alas. For official recording purposes, we will err on the side of caution and record this as a Herring Gull. The odds are against Iceland Gull, and all we can really play here are the odds.
And now, for a completely unrelated photo. Anna Bass, who Seanets in Maine, sent this picture to us, and I love it! While not dead birds, these guys are just so cute! In a very professional, sciency way, as I told Anna. I know they aren’t dead, but want to try your hand at an i.d. on the species here? Anyone?