Monday, October 25, 2010

Quiz #371 (2010-4-04) Solution

Click on picture(s) for a larger view.
No ABA-area rarity is present in this picture.

Answer by Tony Leukering

Though 16 individuals made up this quiz, for most respondents, the only real question was "What is that second shorebird?", and only four respondents got that bird to the correct genus. So, we'll leave that one for last.

The first shorebird is the hefty black-and-white thing with an extensively orangish-red bill, which was ID'ed by all as an American Oystercatcher (the dark tip to the bill lets us know that it's a juvenile). There are three ducks, one of which has a hidden head. However, it is the same size (roughly) as the other two and has a long, low-slung body, whitish tail, orange legs, and rufousy flanks with some internal markings on the individual feathers. These features make it a good match for the two other ducks, which by their overall brownish coloration, massive orange bills, and dark-yellow eyes are known as female Northern Shovelers; the partly-hidden bird is a male Northern Shoveler still in mostly alternate (or eclipse) plumage.

Now, onto the gulls. Do I hear an "Amen!"? There are 11 of 'em and all look about the same size. In the front right corner, there is a nice brown thing that most probably immediately pegged for a juvenile Laughing Gull (though it has started its pre-formative molt, as evidenced by some gray scapulars), as there just aren't any other options sharing the bird's long black wings with little or no white primary tips, white underparts, smooth brown head, and black bill. The young gulls behind this one and the one to the right of the American Oystercatcher are quite similar, though the left of the two does have fairly distinct white primary tips. We might consider Franklin's Gull for that bird, but its back and wings are not nearly scaly enough and the wings are too long for that bird to be a Frankie. Also, there's no suggestion of a Franklin's Gull half-hood.

The adult gulls in the picture all have medium-gray mantles, with most showing either black legs or a black bill; none show a half-hood and the ones on which we can see the head well, there is little in the way of black there. So, these are all Laughing Gulls, too. The two gulls in the back left are both 1st-cycle Laughing Gulls, though the case may be difficult to prove on the left of the two. Regardless, it's not identifiable as any other species, seeing as how they're roughly the same size as all of the other Laughing Gulls.

Now, that second shorebird. The first aspect of it that we ought to note is its size -- in fact, that is a feature that we should almost always judge first, when possible. The bird appears nearly as large as a Laughing Gull. Though the feeding posture appears very dowitcher-like, the size should rule those species out, as does the extensively pink base to the bill. Willet was also promulgated by multiple respondents, but the color of the bill base should eliminate that option, as does the single obviously and distinctly black-and-white lower scapular. This bird's size and bill color should leave us no options other than the godwits and curlews (which, of course, includes Whimbrel), with the latter group ruled out by that same black-and-white scapular. Once among the godwits, Black-tailed is ruled out by the red-text caveat with the picture, because that species is an ABA-area rarity.

At this point, I'm glad that no one provided Bar-tailed Godwit as an answer, as I don't know how to rule that species out with the view that we have. I had meant the caveat to say that there were no NEW JERSEY rarities included, but good intentions being what they are.... Suffice it to say that the bird is not a Bar-tailed Godwit. Marbled Godwit should look larger than a Laughing Gull and lacks our birds strongly white distal half of the underparts.

I took this picture of three Northern Shovelers, one each American Oystercatcher and Hudsonian Godwit, and 11 Laughing Gulls from the hawkwatch platform at Cape May Point SP, Cape May Co., NJ, on 19 September 2010. Ben Coulter gets kudos for being the only person to get the second shorebird right, but also for providing the list of species in his answer in taxonomic order! Below, I provide another picture of the same godwit that I took on the same date to prove the ID.

Incorrect species provided as answers:
Long-billed Dowitcher - 1
Short-billed Dowitcher - 3
Willet - 2
Whimbrel - 2
Common Eider - 1
Mallard - 1
Lesser Black-backed Gull - 1
Marbled Godwit - 3
dowitcher, sp. - 2

Congratulations to the 1 of 15 getting the quiz correct:
Ben Coulter

Answer: Northern Shoveler, American Oystercatcher, Hudsonian Godwit, and Laughing Gull