Monday, April 4, 2011

Quiz #393 (2011-2-01) Solution

Click on picture(s) for a larger view.

Answer by Tony Leukering

When we birders encounter a bird, we start the ID process with certain assumptions -- no matter our skill and knowledge levels. We may not recognize the fact, but it is true. In my experience with a wide variety of birder skill levels, one of the features that separate the highly-skilled birders from the less-skilled is their recognition of many of these assumptions and the ability to weigh those assumptions, throwing one or more away when they are felt to be unjustified. Granted, the highly-skilled also recognize more birds so that they don't actually have to go through the ID process at all.

Though my rationale for using this week's picture in the CFO Photo Quiz was not to test assumptions, it certainly wound up doing that. The fact that the quiz bird is obviously a shorebird adds another layer (at least) of assumptions -- some of which do not deal directly with the ID of the bird -- onto the problem of identifying it. One such assumption may be one of the causes behind the dramatic reduction in Monday responses to the quiz, compared to last week's: nine Monday this week vs. 25 last week. Shorebirds comprise a group that many birders feel uncomfortable with, and such birders may delay their response to the quiz to allow time for study or, even, not respond at all. This, despite the fact that this week's quiz subject is presented much better and larger -- we can see nearly the whole bird -- than was last week's. The main point of all this jabbering about assumptions, is that if one starts with an incorrect assumption, one can find it difficult getting to the correct answer.

Though I am not picking on those that provided incorrect answers, those answers do provide some insight into the types of assumptions that can be made that can lead one astray. At least one respondent started with the assumption that the quiz bird was a peep, and the short legs and chunky body certainly give that impression. The long wingtip projection then cuts down the list of options to just Baird's and White-rumped sandpipers. Once there, given how gray the bird is, White-rumped Sandpiper seems the best fit.

Though I don't know the assumptions of the respondent providing the answer of Short-billed Dowitcher, I can guess that the bird's chunkiness and grayness may have been two of the factors. Of course, once in the dowitchers, the bird's incredibly short bill must lead to Short-billed. The assumptions at the root of the Willet, Dunlin, and Stilt Sandpiper answers probably lie in the bird's gray coloration.

This is where close scrutiny of one's assumptions come into play, because, as one can see in the enlarged version of part of the quiz picture, the bird has yellow legs, which rules out four of the six incorrect species provided as answers. If one cannot get past one's assumptions that the bird must be of a certain group of species, then one might overlook the fact of the yellow legs. Or that the bird has quite short legs.

This is the point at which I thought my solution would start way back in January when I posted the quiz picture: It is not enough to prove to oneself what the bird is, but one should also prove what it is not. (This is certainly true when trying to convince a records committee of one's identification.) Had the respondents taken that tack, they might have rethought things from the beginning, particularly their assumptions.

Our shorebird has gray upperparts; very short yellow legs; a shortish to medium-length bill; a tail that appears all gray and unmarked (even the outer rectrices); barring on the sides; and a nearly-unique pattern on the scapulars. Yes, some of these features are found on the various incorrect species, but nowhere near all of them. This fact points out how strong our assumptions can be at overpowering our ability to correctly identify unknown birds, because the highest number of the above six characters shared by our quiz bird and the incorrect species is three (for White-rumped Sandpiper and Short-billed Dowitcher). The number declines if we actually consider the age of the bird and the features associated with that age.

Ageing the bird properly might have pointed out the problems with some of those incorrect answers much sooner. The pattern of fringes on those browner feathers should tell us that they're juvenal feathers, with the unmarked gray ones up top being of the next generation of feathers, thus formative plumage. This bird is less than a year old, certainly, and probably well less, considering that those juvenal feathers do not look all that worn.

By noticing those fringed juvenal scaps, one might have reconsidered Willet as an answer, as that species never has fringed feathers such as these. Also by noticing those scaps and the resultant age estimation, the barring on the sides would have ruled out all of the incorrect answers. By truly noticing those scaps, one might have noticed the distinct pattern on them. Once that was noticed, one might have gone back through the basal assumptions and the field guide(s) to find a bird that sports such scaps -- there are only two. This bird is not a Temminck's Stint, which would be browner and with buff fringes to those scaps and would lack our bird's side barring.

Steve Mlodinow took this picture of a 1st-cycle Red Knot on 20 November 2010 at Tokeland, Pacific Co., WA.

One respondent's answer was precluded from being correct for the competition as it included an incorrect plumage assignment directly in the response; please keep any other conjecture about the bird separate from one's species answer.

Incorrect species provided as answers:
Stilt Sandpiper - 1
Willet - 2
Short-billed Dowitcher - 1
White-rumped Sandpiper - 3
Baird's Sandpiper - 1
Dunlin - 1

Congratulations to the 27 of 36 getting the quiz correct:
Thomas Hall
Brandon Percival
Ben Coulter
Christian Nunes
Margaret Smith
Al La Sala
Tyler Bell
Devich Farbotnik
Su Snyder
Kara Carragher
Pam Myers
Adrian Hinkle
Peter Wilkinson
Louie Toth
Christopher Hinkle
Nick Komar
Diane Porter
Robert McNab
Richard Jeffers
Margie Joy
Michael McCloy
Buzz Schaumberg
Marcel Such
Matt Bristol
Chishun Kwong
Bryan Guarente
Joel Such

Answer: Red Knot