Monday, November 15, 2010

Quiz #374 (2010-4-07) Solution

Click on picture(s) for a larger view.
Three views of the same individual

Answer by Tony Leukering

Presumably due to the combination of wing bars, flank streaking, and yellow underparts, all respondents thought that this week's quiz bird was a warbler. The important bits to notice on the wee beastie are:

1) whitish wing bars that are not that prominent (seen best in the right (R) picture, and blown out of proportion in the L picture);
2) blackish flank streaking (L and center (C) pictures);
3) undertail covert color (L);
4) face pattern (C and R); and
5) back color (R).

While leg color might also have been a feature to study, all of the similar species share this species' leg color: black. There aren't that many warbler species that combine yellow underparts with blackish flank streaking, and most of those sport white undertail coverts. Our bird's pale yellow undertail coverts (contrastingly paler than the ground color of the flanks) would be the first and one of the more deadly strikes against Magnolia and Cape May warblers, the former due to the color of the undertail coverts, the latter only partly so. Some Cape Mays have yellow-washed undertail coverts, but those tend to be adult males and those exhibit whitish flanks.

Palm Warblers do have yellow undertail coverts, but they are at least as bright as the flanks (Yellow Palm Warbler) if not brighter (Western Palm Warbler); they are never duller. Additionally, the color of the flank streaking is incorrect for that species. The greenish back helps rule out Kirtland's, which is also ruled out by the yellow undertail coverts, and blackish flank streaking rules out the only non-Dendroica provided as answers by respondents, Orange-crowned Warbler.

Despite all of the above, the back and face are sufficient unto the day to identify our quiz bird. Though very subtle, the bird's back has a hint of reddish streaking. The face, however, is not as subtle. There are large pale areas above and below the eye and a distinctly darker bottom edge to the auriculars and a dark eyeline behind the eye. Those pale areas around the eye are not thin and well-defined, but broad and blurry. The combination of features presented lead to only one solution, with the final two being definitive individually.

I took these pictures of an immature Prairie Warbler from the hawkwatch platorm at Cape May Point SP, Cape May Co., NJ, on 11 September 2010.

Incorrect species provided as answers:
Palm Warbler - 2
Orange-crowned Warbler - 1
Magnolia x Prairie Warbler - 1
Cape May Warbler - 1

Congratulations to the 16 of 21 getting the quiz correct:
Ben Coulter
Chuck Carlson
Jim Mountjoy
Margaret Smith
Marcel Such
Joel Such
Su Snyder
Nick Komar
Brandon Percival
George Cresswell
Margie Joy
Peter Wilkinson
Tyler Bell
Adrian Hinkle
Christopher Hinkle
Chishun Kwong

Answer: Prairie Warbler