Lesser Black-backed Gull!
You might think it is yet another Great Black-backed Gull . . .
unless you saw it standing next to Great Black-back Gulls. This gull is clearly smaller than a GBBG; it is paler in color than a GBBG; and it has yellow legs instead of the GBBG's pink legs.
Or, you might assume it is just a Herring Gull . . .
but this gull is smaller, thinner, and darker than a Herring Gull. What is it? It is a Lesser Black-backed Gull! Lesser Black-backed Gulls are "uncommon to rare visitors from Europe," according to my Sibley Field Guide to Birds of Eastern North America (2003). They are "smaller and more slender than Herring," and "much darker gray above than Herring, and usually slightly paler than the Great Black-backed Gull; note yellow legs and mostly black wingtips" (Sibley p188).
Doesn't the Sibley description perfectly describe this bird? I've gone through all my field guides and all over the web trying to prove myself wrong about this, and I couldn't.
It is not a dark Herring Gull or a light GBBG - both of those species have pinkish legs.
It is not remotely similar to a Ring-billed Gull, either. Ring-billed gulls do have yellow legs, but they are much lighter colored and the bill is all wrong.
I read up on Lesser Black-backed gulls before our trip, which is why I was able to recognize the species in the first place. According to Massbird, there were two Lesser Black-backed gulls on South Beach last week, but I never expected to see one myself. My son Pete quickly snapped these pictures - I didn't bother with pictures because I didn't believe it was real! It is a good thing Pete was snapping away, too. It's thanks to him we have pictures of the bird at all. Better still, we have pictures of this gull together with local gulls, so we can compare sizes and colors!
What do you think? Am I right? Or am I missing something big? If so, let me know what you know!