Monday, October 12, 2009

Quiz #321 (2009-4-03) Answer

Answer by Tony Leukering

We have a seemingly obvious shorebird with a vaguely two-toned bill, whitish dots on the brownish back, obvious spectacles, and strongly black-and-white barred underwing feathers. We can see a bit of each of the bird's legs, one in sun, one in shadow. The shadowed leg looks greenish, the sun-dappled leg somewhat dull yellowish.

The longish bill rules out most (if not all) of the Calidris sandpipers and sends us to the recently-expanded genus, Tringa. With the subsuming of Actitis, Catoptrophorus, and Heteroscelus into Tringa, some well-known species (Spotted Sand, Willet, and Wandering Tattler) are now housed in the same genus as the two yellowlegs, Tringa. The strong underwing barring may suggest Wandering Tattler, but that pattern does not extend onto the underparts, so that species and the other tattler are removed from consideration. In fact, the darkness of the wings, both upper and under sides, should take us quickly to Solitary Sandpiper. At this point, the white eye rings connected to whitish supraloral stripes (making spectacles), the small white spots on the upperparts, and the leg color all serve to reinforce that snap ID. However, there are similar species occurring in the ABA area, and we should always consider them when ogling a Solly Sand. We should consider Wood Sandpiper, in particular, as it has occurred in both New York and Delaware, thus could occur virtually anywhere in the ABA area.

The darkness of the underside of the wings argues most strongly against an ID of Wood Sandpiper, but Green Sandpiper is still in play. However, that species shows a more uniformly black underwing at odds with our quiz bird. Thus, our snap ID has proven correct.

But, I implore observers to keep studying the bird, as naming a bird is not the end-all, be-all of birding. Solitary Sandpiper comes in two subspecies, nominate solitaria and western cinnamomea. Adults are essentially indistinguishable in the field, but juveniles are fairly readily determined given reasonable views. Also, given the suggestion by some (particularly Herbert, P.D.N, M.Y. Stoeckle, T.S. Zemlak, and C.M. Francis (2004)) that cinnamomea is a cryptic species, we should all become more familiar with the two subspecies and their distributions -- which have not been worked out all that well. (Note, though, that the methodology used by Herbert et al. (2004) has been called into question by many; we await a definitive yea or nay.)

While some field guides illustrate the two, this is really a job for Pyle, part II, the second part of the landmark Identification Guide to North American Birds that is primarily written for banders, but which is eminently useful for field birders. Within the book, Pyle notes the following criteria for separation:

solitaria: "upperparts and lores dusky blackish, the back with whitish spots in Juv; p10 [the outermost primary] with darker shaft and without whitish mottling to inner web."

cinnamomea: "upperparts and lores brownish, the back with buff spots in Juv; p10 with paler shaft and (often) whitish mottling to inner web."

To my eyes, our bird's upperparts and lores look brownish, which should point us toward cinnamomea. As I interpret the darker vs. paler p10 shaft as meaning relative to each other, we cannot use this character as we've got only one bird. However, realize that a pale shaft to p10 is a widespread character in Charadriiformes, the order including shorebirds, gulls, terns, skimmers, jaegers, and alcids.

The spotting on the bird's back looks white or whitish, and that leads us back to solitaria. Additionally, there is no apparent mottling on the inner web of p10, a feather that we can see very well on the bird's right wing; another solitaria feature, but note the qualifier ("(often)") in the cinnamomea account. So, that leaves us with 1 character state for cinnamomea and 1.5 for solitaria. Of course, the most easily seen-and-assessed-in-the-field character is the back spotting, so, perhaps we should give it more weight. I am leery, though, of the character for a couple of reasons: 1) many birders have relatively poor color-shade discernment capabilities and 2) buff tends to wear/bleach toward white, so a worn juvenile with white spots may be referable to solitaria or it may be a worn cinnamomea. I have had no opportunity to determine if this ever happens in "real life," but I can certainly imagine it happening. Finally, I would suspect that a "vagrant" of either might show up late in the season and that would make subspecific determination even trickier.

This juvenile Solitary Sandpiper occupied a sky pool in the circle at Cape May Pt. S.P., Cape May Co., NJ, for three days in early October 2009 where I photographed it on the 13th. By range, it ought to be a solitaria, but....

After three quizzes in the quarter's competition, only four are sitting pretty with perfect scores: Peter Burke; Kevin Kerr; and the Such brothers, Joel and Marcel.

Incorrect species provided as answers:

The 23 of 23 providing the correct answer:
John Bissell
Margaret Smith
Nick Komar
Kevin Kerr
Jeff Jones
Aaron Brees
Tyler Bell
George Cresswell
Al Guarente
Su Snyder
Tara Nelson
Mark Dettling
Chris Sheridan
Bryan Guarente
Joel Such
Peter Wilkinson
Peter Burke
Andy Dettling
Margie Joy
Robert McNab
Barbara Deneen
Marcel Such
Chishun Kwong

Answer: Solitary Sandpiper