Monday, August 15, 2011

Quiz #412 (2011-3-07) Solution

Click on picture(s) for a larger view.

Solution by Tony Leukering

Once again I neglected to put in the intended caveat with a quiz picture, so I suspect that one of the five birds present scared some number of people away from responding to the quiz. Four of the birds were apparently thought to be quite easy, as no respondent missed them, what with the obvious black on the bellies and the bright bubble-gum-pink legs. However, three respondents neglected the second hyphen in "Black-bellied Whistling-Duck," so their answers were precluded from being correct for the competition.

I received answers claiming that fifth bird as Gadwall, Mallard, Mottled Duck, Northern Shoveler, Cinnamon Teal, and Blue-winged Teal, though a number of respondents did not even try (or, perhaps, did not think it a different species). However, I had intended to provide the caveat that respondents need not attempt ID of the bird lacking bright pink legs, but that bonus points would be awarded for its correct ID with no penalty for incorrect answers. Though I forgot it, I scored things as if I hadn't, giving one bonus point for the one respondent getting the ID to the wrong one of a tricky species pair (particularly tricky given this view) and two bonus points for the correct answer, because I didn't really see much in the way of definitive features to separate the two species here.

On the tricky bird, the belly is just too pale to be one of the dark Mallard-like dabblers and lacks a white tail, so Mallard and Northern Shoveler are eliminated from consideration. As the bird is noticeably smaller than the whistling-ducks, that, too, would rule out the Mallards and Mallard-like species and provide at least one strike against Gadwall, wigeons, and Northern Pintail. The extensive spotting on the belly provides the other two strikes against the wigeons and another strike each against Gadwall and Northern Pintail. The pattern on the flank feathers sends both Gadwall and Northern Pintail back to the dugout, as both species have more complex patterns there. Just to add insult to striking out, the quiz bird's squarish tail is a fourth strike and the leg color a fifth strike against an ID of Northern Pintail, which has a pointed tail and dark legs.

The bird lacks the distinctive pale wedge on the side of the undertail coverts that is so distinctive of Green-winged Teal, nor does that species have orangish legs. That leaves us, among the common ABA-area dabbling ducks, with that tricky duo, Cinnamon and Blue-winged teal. Though Cinnamon Teal averages warmer-colored and less-distinct markings on the belly and undertail coverts, I'm not convinced that the feature is diagnostic at the colder, more-distinct end of things, but I do know that the bird was not a Cinnamon Teal.

Doug Gochfeld took this picture of four Black-bellied Whistling-Ducks and one Blue-winged Teal at the South Cape May Meadows, Cape May Co., NJ, on 19 September 2010. Particular congratulations to Christian Nunes for getting both species correct, even if it was just "a gut reaction."

Incorrect species provided as answers:

Congratulations to the 16 of 16 getting the quiz correct:
Al Guarente
Tyler Bell
Pam Myers
Su Snyder
George Cresswell
Thomas Hall
Kirk Huffstater
Margie Joy
Diane Porter
Peter Wilkinson
Robert McNab
Joe Bens
Christian Nunes
Marcel Such
Chishun Kwong
Bryan Guarente

Answer: Black-bellied Whistling-Duck, Blue-winged Teal