Quiz photo taken late October.

Ahh, one of those pale, gull things. At least it’s not a member of Larus! Or is it?

The bill looks mostly or entirely black, so Glaucous Gull is ruled out. Of course, early in their lives, juvenile Iceland Gulls – including Thayer’s Gull – (Thayer’s Gull is dead. Long live Thayer’s Gull.) have all-black bills. It also has not much black in the wing tips, so young Thayer’s Iceland Gulls are ruled out. Right? But aren’t young Iceland Gulls sort of, I don’t know, biscuit-colored? This bird looks gray-winged, lacking any brown tones.

Perhaps it’s some funky age of one of the gull species with black or, in the case of Black-headed Gull, brown heads as adults in the breeding season. At least, the bird’s bill is more in line with something in that group of gulls than those Larus things, which typically sport a pronounced gonydeal angle.

What’s a gonydeal angle? Oh, that’s that angle on the mandible (aka lower mandible – but, ick, blech, and other such words indicating disapproval when there’s a perfectly good word for the “upper mandible”) created by the downward slope of the bill tip meets the lower edge of the bill at the… wait for it… gonys.

Remember this quiz photo from November 2021?

See where the dark band around the bill reaches the bottom edge of the bill. That’s where the gonys is. The gonydeal angle on this Herring Gull is fairly typical of the genus… so long as one considers only those species that sport relatively intermediate angles. Some Larus sport ones like this, some have sharper angles, some have shallower angles, some have, essentially, no angle at all. However, the lack of a distinct gonydeal angle rules out most Larus species, leaving the small-billed species such as Mew… oh, I mean “Short-billed,” Ring-billed, and California.

Wait a minute! Did we or did we not assume that the quiz bird is not a member of Larus?

Ah, but we need to be thorough and make sure we did not pass by a reasonable option.

Oh. Well, if we must.

We must, because I’ve already gotten the next part written, and I had to insert this digression solely to make the whole consistent.

What’s that quote about consistency?

Which one? There are many. Perhaps you’re thinking of Ralph Waldo Emerson:A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines.Or, mayhaps the ultimate in short, sharp rebukes, Oscar Wilde:Consistency is the hallmark of the unimaginative.

Aren’t you arguing my side?

Ah. Here’s that next bit, anyway.

The eyes of all three species (just in case you forgot where we were: Short-billed, Ring-billed, California) are dark in younger plumages, so that works, but all three are variably brown-headed as juveniles, and with the first and third of those species retaining a strong brown color to their head after their first molt after replacing the downy plumage in which they hatched, but all three have extensively black or blackish wing tips at that time. Our quiz bird certainly does not. Oh, yes, and did I mention the bicolored bills of older individuals of first-years in all three species.

So, it’s into those smaller gull things that are easier to identify mostly because there are so many fewer real choices in most locales. Laughing Gull is extensively brown in its first-year plumages. Franklin’s is not, but always sports significant amounts of black on the head. While the quiz bird seems to have some dark behind the eye, that dark does not coalesce into a distinct and dark ear spot, ruling out Little, Black-headed, Bonaparte’s, and Ross’s gulls, as well as the two kittiwakes species. Sabine’s, while typically not sporting an ear spot, does sport significant dark plumage on the head. Well, that leaves us with zero good choices.

In bird ID, when one paints oneself into a corner leaving no reasonable ID options, it’s best to go back and reassess one’s initial assumptions.