Quiz #382 (2011-1-03) Solution

No ABA code 3 species (or rarer) in picture

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Answer by Marcel and Joel Such and Tony Leukering

The brothers Such provided good solutions, so I'm running with 'em. I find the slightly different tacks they took to get the correct solution interesting and beneficial, particularly as they cover slightly different bases and do my job for me, and well. The first responding of them this week was Marcel, so take it away!

"To start off this quiz, we should immediately note that there are nothing but gulls in the photo, and with the hint that 'No ABA code 3 species (or rarer) in picture,' we can directly limit ourselves to just 19 species. As with the last quiz, we’ll check to see how many species are present. All of the birds, minus the bird in the immediate foreground of the photo, all share distinctive black “ear-muffs,” thin black bill, and tiny white tips on their otherwise black primaries, so I feel confident that these are all of one species. The closest bird, however, is obviously different, being distinctly larger, with a dark gray back; partial dark hood; and thick, slightly drooping, dark bill.

"For the species-specific identification, let us start with the smaller, more abundant, gulls. Of the 19 sub-code 3 species, only three species have the obvious dark ear-muffs, Black-legged Kittiwake, Red-legged Kittiwake, and Bonaparte’s Gull. Of these, only one species has a thin, black bill, Bonaparte’s. The kittiwakes all have thicker, shorter bills of a bright yellow hue.

"For the second species, only three options, Franklin’s, Laughing, and Sabine’s, have the distinctive dark partial hood shown by our bird. From here, Sabine’s can be quickly eliminated because of its comparatively shorter, thinner bill, with a distinct yellow tip. Franklin’s can also be eliminated by its thinner, straighter bill and its white nape (our bird’s is gray). This leaves us with Laughing Gull, which matches our bird exactly."

And now for Joel:

"Comparing all the birds in this photo, it looks like there are two species, obviously gulls. There are six small hooded gulls and one medium-sized hooded gull in winter [basic or formative, depending upon age] plumage.

"The small hooded gulls: All the gulls except for the bigger browner gull in front are small hooded gulls. Field marks on these non-breeding-plumaged birds are dark ear spot; thin, black bill; somewhat-light gray back; and dark primaries. They cannot be Little Gulls, due to the lack of a dark cap. Black-headed Gull can be eliminated, as they lack the heavier red or orange bill. Bonaparte’s Gull, on the other hand, is a perfect fit, matching all the other field marks that are present on the six small hooded gulls in the quiz photo. Other considered birds are both Kittiwakes, which don’t have the right bill or the correct head pattern.

"The medium-sized hooded gull: The gull in the front is obviously of a different species than all the others gulls, being either a Franklin’s Gull or a Laughing Gull. The brown wings and gray hindneck with a dull half hood make it a first-winter bird. It’s not a Franklin’s Gull, which has a whitish hindneck and a more distinctive hood, leaving Laughing Gull as our winner, with its rather heavy, long, slightly drooped dark bill; white forehead and throat; dark auriculars and neck; and brownish wings."

Thanks, guys!

Because they weren't quite specific enough about a couple bits, I'll finish things up. Black-legged Kittiwakes as juveniles have black bills, but in that plumage they also sport that whacking big nuchal collar. While Red-legged Kittiwakes lack that collar as juvs, they also have very tiny bills and very large eyes (relative to head size), which our quiz birds lack. I believe that Joel is right and the Laughing Gull is a first-winter (in formative plumage), but the Bonaparte's are a mix of two ages (readily told by the black in the wing coverts), with two adults, three first-winters, and one of undetermined age present.

I took this picture of six Bonaparte's Gulls and one Laughing Gull off Delaware on 23 November 2010. They were part of a HUGE feeding frenzy including some 1500-2000 Bonaparte's Gulls, 300 Laughing Gulls, 30+ Black-legged Kittiwakes, 20+ Great Shearwaters, a few Manx Shearwaters, and 9+ Parasitic Jaegers (with a few big gulls and a smattering of Northern Gannets thrown into the mix, too). The system works like this: It starts with a big school of baitfish (e.g., Sand Eels [Ammodytes sp.] or Anchovies; this time, Sand Eels, I think -- "Rock me, Ammodytes!") and the big schooling predatory fish, in this case Bluefish and Striped Bass, attack them from below, forcing them to the water's surface. At this point, the gulls and shearwaters can get 'em and start gorging. The final bit is the jaegers pirating the gulls' and shearwaters' free lunches from them.

Two of the three respondents providing only one species in their answers got that one species correct (Bonaparte's).

Incorrect species provided as answers:
Sabine's Gull - 1
Franklin's Gull - 2
Black-legged Kittiwake - 2

Congratulations to the 20 of 26 getting the quiz correct:
Brandon Percival
Christian Nunes
Al Guarente
Pam Myers
Ira Sanders
Tammy Sanders
Chuck Carlson
Ben Coulter
Marcel Such
Kirk Huffstater
Joel Such
Nick Komar
Tucker Lutter
Margie Joy
Matt Bristol
Christopher Hinkle
Adrian Hinkle
Joe Bens
Chishun Kwong
Bryan Guarente

Answer: Bonaparte's Gull, Laughing Gull

Quiz #381 (2011-1-02) Solution

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Answer by Tony Leukering

First off, I gave an extra bonus point to all those providing a correct answer for the white-headed shorebird in the background that was supposed to have been cropped out of the quiz picture; it is a Sanderling, and no one got that species wrong that provided a species name for it (others were not penalized). Secondly, I was expecting that respondents would have trouble with the Pluvialis plovers -- they can be truly difficult, but was a bit surprised by the difficulty that respondents had with the four yellow-legged sandpipers.

With both sets of focal species proving a bit tricky, where to start is critical, as each species can inform on the other, particularly with size comparison. So, as the bird exhibits a very distinctive feature, I'll start with the top right of the four sandpipers. These four are dumpy and have short yellow legs (note the emphasis on the first modifier), a medium-length bill, and little in the way of plumage distinction (being brownish-gray above and whitish below), except for one key feature. That feature is the distinctive pattern to most of that upper right sandpiper's upperparts feathers: solid brown except for a thin white fringe and a dark subterminal band (one does need to enlarge the pic to be sure of the pattern). Only two ABA-area shorebird species sport this pattern, one of them being Temminck's Stint. Though bill length and/or leg length can rule out all the species incorrectly provided by respondents, these distinctive feathers do an even better job of ruling them out, as they are juvenal feathers of Red Knot. Temminck's Stint is ruled out by the birds' size; any Pluvialis would dwarf Temminck's Stint. Once we know that the sandpipers are Red Knots, all the shape features line up quite nicely: both bill and legs are too short for Stilt Sandpiper, the legs are too short for either Pectoral or Sharp-tailed sandpipers, and the birds are too large for Least Sandpiper.

With the plovers, it is key that they are all the same size, or virtually so, suggesting that they are all either Black-bellied Plovers or some combo of golden-plovers, not both. The picture is over-exposed (and I purposefully left it that way), so we might be a little wary of the color of the spangling on the upperparts, as golden spots might have been "blown out" by the overexposure, so the more "golden" species (European and Pacific) are not immediately ruled out by what appear to be whitish spangling. I will start with the front left bird. It is mostly brown with whitish spangling above, but it has a number of black-and-white feathers; these must be remnants of alternate plumage, thus the bird must be an adult. At least four other of the plovers show at least some trace of alternate plumage. Others, however, appear to be sporting at least some juvenal plumage. This combo of ages with the adults nearly out of alternate plumage suggest that the picture was taken later in fall, perhaps October or November. A number of the birds exhibit very long primary projection, while a couple show either shorter projection or are indeterminant. Thus, if these are golden-plovers, they have to be Americans or a mix of American and Pacific. However, Black-bellied, too, has very long primary projection, so that species is still in the hunt.

Bill size and shape is one of the better features allowing separation of Black-bellied from the various golden-plover species, but I find that it's often difficult to use in isolation, that is, with only one species present. To me, the bills look quite long and relatively thick, but I need not rely on that feature, because there are still a couple of very useful plumage bits that are very good species determinants. The bellies on all the plovers on which we can see them appear whitish (American and Pacific golden-plovers are grayish), while the crowns on most of them are pale and do not contrast darker than the rest of the head (as in all golden-plovers), except for the bird in the center holding the most alternate plumage and the bird in the back facing right. That back bird might, indeed, be a good candidate for a golden-plover, as it seems warmer, but that could be the angle in which the bird is standing relative to that of all the others. However, looking at head shape, we can see that it's head appears to be deeper from front to back than it is tall, while golden-plover heads are roughly the same dimensions front to back and top to bottom. Finally, Red Knots are of about the same size as the various golden-plovers, but are noticeably smaller than are Black-bellied Plovers.

Incorrect species provided as answers:
Least Sandpiper - 2
Sharp-tailed Sandpiper - 1
Pacific Golden-Plover - 4
Pectoral Sandpiper - 3
American Golden-Plover - 5
Stilt Sandpiper - 1
Rock Sandpiper - 1
Ruddy Turnstone - 1
Purple Sandpiper - 1

Congratulations to the 11 of 23 getting the quiz correct:
Ben Coulter
Christian Nunes
Al Guarente
Peter Wilkinson
Adrian Hinkle
Pam Myers
Christopher Hinkle
Tucker Lutter
Matt Bristol
Chishun Kwong
Joel Such

Answer: Black-bellied Plover, Red Knot (and Sanderling)