Monday, August 22, 2011

Quiz #413 (2011-3-08) Solution

Click on picture(s) for a larger view.

Solution by Bryan Guarente and Tony Leukering

I am quite pleased with the responses this week, as at least three included mention of the field mark that this quiz photo was attempting to point out. This week's quiz bird, with its extensive black on chin, throat, and upper breast; bright yellow face; and distinct black streaking on the sides should take us straight to the Parulidae. This combo of characters should also tell us that the bird is in alternate plumage and must be a male. From there, I will let Bryan Guarente's words take us down the ID track for a bit.

"The possibilities are Black-throated Green, Townsend's, and Golden-cheeked warblers. Where to go from here? I initially went to the face as lots of birders do and there noted a thin, black eyeline. That feature cuts out Townsend's Warbler, which has a more extensively black face. However, we don't even need to do that, as we can head toward the other end of the bird for our answer. Most warblers can be identified by looking at the tail area. In this case, the vent, the feathers around the part that would vent any gases. (I don't get to use that joke very often, so I had take advantage of the opportunity.) These feathers are tinged yellow, which clinches the ID: Black-throated Green Warbler is the only one of the warblers in our list that sports this characteristic."

Bryan is correct about the yellow vent strap in Black-throated Green Warbler, an excellent field character in all post-juvenal plumages of the species, and one that even many experienced birders don't know. Other characters that rule out the other species of the virens complex species include the bit of yellow below the bib (rules out Golden-cheeked and Hermit warblers), the streaking on the sides is much too extensive for Hermit Warbler, and the lack of dark streaking on the undertail coverts rules out Townsen's Warbler. Note that this individual is readily identified with multiple characters south of the legs.

I took this picture of an adult male Black-throated Green Warbler at the recently renamed Cox Hall Creek WMA (formerly Villas WMA), Cape May Co., NJ, on 1 May 2011.

Incorrect species provided as answers:
Golden-cheeked Warbler - 1

Congratulations to the 18 of 19 getting the quiz correct:
Thomas Hall
Dave Elwonger
Chuck Carlson
Kirk Huffstater
George Cresswell
Burke Angstman
Tyler Bell
Margie Joy
Robert McNab
Pam Myers
Al Guarente
Chishun Kwong
Diane Porter
Su Snyder
Christopher Hinkle
Peter Wilkinson
Marcel Such
Bryan Guarente

Answer: Black-throated Green Warbler