Monday, July 13, 2009
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Answer by Tony Leukering
Yet another quiz picture of the south end of a north-bound bird. As Chuck Carlson noted, "This is not a view normally illustrated in the field guides...." Perhaps, it should be, as I certainly see enough of disappearing hindquarters in the field to be able to make good use of such illustrations!
As all respondents noted, this week's quiz bird is a sparrow; the overall brown color, extensive streaking, and pink legs certainly make that a good starting group. Though most respondents got the correct answer, even some that did noted that the quiz was tough.
Though streaking may be considered a typical feature of sparrows, many are, at least as adults, unstreaked below -- virtually all of 'em have streaking on the back. Of course, note that I qualified the above with "as adults." Could this be a juvenile bird in typically streaked juvenal sparrow plumage? Well, a quick look at a bit of the bird that we can see well, the undertail coverts, tells us that the beastie is not in juvenal plumage, as those feathers do not appear weak and fluffy. So, on to adult sparrows.
There are, actually, very few sparrows that show such obvious streaking on the flanks and undertail coverts: Lincoln's Sparrow and some forms of Savannah, Fox, and Song sparrows. The strong rufescent tones in much of the plumage and the gray bits on the head rule out Savannah. Those Fox Sparrows that have streaking on the undertail coverts lack, or mostly lack, it on the back, and those with back streaking have different color streaking there and lack undertail-covert streaking.
That leaves us with a sometimes-difficult duo, Song and Lincoln's sparrows. Were the bird in hand, we could almost certainly ID it as a Song, as Lincoln's almost always erect the crown feathers into a crest when in the hand. However, the bird is not in the hand and we must look elsewhere for our ID. And, for that, we'll go back to the undertail coverts, a tract of feathers that is very useful for ID, but greatly overlooked. We can see that the ground color of most of these feathers is buffy and that certainly suggests Lincoln's Sparrow, though at least some Song Sparrows, particularly in the western race morphna, sport such. But, the color of the streaking on the undertail coverts (and on the flanks) is black, not the reddish color of morphna or most other races of Song Sparrow. I provide, below, another picture of the same Lincoln's Sparrow photographed by Rachel Hopper 16 May 2008 in Fremont Co., CO, during the annual Colorado Field Ornithologists' convention.
I received one correct answer that arrived after the deadline.
Incorrect species provided as answers:
Seaside Sparrow - 1
Song Sparrow - 2
The 20 of 23 providing the correct answer:
Answer: Lincoln's Sparrow