Monday, September 24, 2012
Solution by Tony Leukering
Even the crew of regular respondents that have won quarterly competitions had problems with this quiz of two streaky sparrows or sparrow-like birds. Careful scrutiny of the two birds, particularly the left one, should set off our alarm bells, as these seem to have the loose, fluffy plumage so typical of juveniles, which can certainly throw off our estimation of specific ID, as all bets are often off with juvs. Since nearly everyone got the right bird correct, we'll start there. This substantial bird, both long and quite chunky, rules out all of the skinny sparrows (e.g., Spizella species). Additionally, the very thick bill rules out a lot of the other options. The buffy-white wing patch, which occupies much of the greater coverts and quite a bit of the median coverts, is a particularly good clue. In combination with the bird's large size (relative to the other quiz bird), we really should entertain the possibility of Lark Bunting, Colorado's state bird. In fact, the head pattern looks quite good for that species, but the thin underparts streaking is not a feature that most of us think of on the species. But, this is, indeed, a juvenile, wearing juvenal (=first basic) plumage, and the thin streaking is typical of the plumage.
Now, for the left bird, which caused no end of consternation, with seven species provided as possible solutions to its ID. It, too, is a juvenile and, given the short availability of the plumage for ogling, most of us don't know juvenal sparrows at all well. Looking at the tail, we might note the suggestion of a whitish edge, though that could simply be an artifact of the picture. The head pattern is not distinct enough for most Spizella sparrows, but too distinct for Field Sparrow, which sports a very dull and plain head. However, the key feature is the bird's strongly rufous greater coverts, a feature of few sparrow or sparrow-like species: McCown's and Lapland longspurs; Bachman's, American Tree, Vesper, Henslow's, Seaside, Song, and Swamp sparrows; and some Savannah and Fox sparrows. Some species -- Lapand Longspur and Bachman's, American Tree, Henslow's, and Seaside sparrows -- can probably be ruled out just on the unlikelihood of finding a fresh juvenal perched on a barbed-wire fence with a juvenal Lark Bunting. Remember, with very few exceptions, juvenal plumage is typically held for a very short time and only a couple of species can be found migrating in the plumage. We are left with the McCown's Longspur and Vesper, Song, and Swamp sparrows. We can rule out the longspur on toenail length -- they're called longspurs for a reason, as the nail on our bird's hind toe is not even as long as the rest of the toe. Additionally, our bird is too streaky below for a McCown's juvenile. Our bird's head pattern is too dull and the underparts aren't streaked heavily enough for either of the Melospiza sparrows and the bird is not streaky enough for a juvenile Savannah. Fox Sparrow would be larger than Lark Bunting. Steve Mlodinow took this picture of juvenile Vesper Sparrow and juvenile Lark Bunting on Pawnee National Grassland, Weld Co., CO, in early August 2011.
Two respondents provided answers with just one species.
As this is the final quiz of the third quarter's competition, it is time to award the prize of a year's membership in Colorado Field Ornithologists. Five respondents ended the quarter tied with 11 correct responses: Ben Coulter, Richard Jeffers, Logan Kahle, Robert McNab, and Sean Walters. The first tie-breaker is the number of incorrect answers, and Richard wins via that one, with just one incorrect response. Congratulations, Richard!
As for the annual competition, Ben Coulter has a one-quiz lead on Robert McNab (35 to 34) for that honor.
Incorrect species provided as answers:
Grasshopper Sparrow - 3
Cassin's Sparrow - 1
Lark Sparrow - 1
Savannah Sparrow - 1
McCown's Longspur - 1
Savannah Sparrow - 1
Field Sparrow - 1
Congratulations to the 2 of 13 getting the quiz correct:
Answer: Vesper Sparrow, Lark Bunting