Monday, February 27, 2012
Click on picture(s) for a larger view.
Solution by Tony Leukering
A slim, grayish sparrow pops up on a branch and gives you the once-over and departs, never to be seen again. Did you get the critical details to identify the bird? The near-lack of field marks gave it away to quite a few. The overall slimness and slim bill points to the Spizella sparrows and the thin-based, long tail keeps us there. Upon arriving at the correct genus, we can eliminate American Tree, Field, and Black-chinned sparrows (and Worthen's Sparrow) by various features, with the primary of these being bill color and pattern and the streaked crown. That leaves us with a trio of species that cause no end of consternation to birders, due to the similarity of various plumages: Chipping, Clay-colored, and Brewer's.
Even the dullest of Clay-colored Sparrows should show more color below than is shown by the quiz bird, while even the dullest of immatures should show a stronger face pattern. Additionally, Clay-colored is the shortest-tailed of the three, and this feature is at least occasionally useful. Chipping Sparrow, though confusable with both of the others, sports a character that is a deal-breaker for this bird -- the strong blackish eyeline that extends, at least, behind the eye, and often well in front of the eye. Regardless, the eyeline is always present enough to split the eye ring, at least behind the eye, a feature not present on the quiz bird.
Many Brewer's Sparrow show something of a whitish central crown stripe, but this bird's is just pale gray. Steve Mlodinow took this picture of an immature (note the differing coloration of the inner vs. outer greater coverts) Brewer's Sparrow in Weld Co., CO, on 11 September 2011.
One respondent's answer was considered incorrect for the competition as it included an incorrect estimate of age directly in the answer. Please, please, please read the rules and keep any estimate of age, sex, subspecies, and whatever else separate from the answer of species.
Incorrect species provided as answers:
Clay-colored Sparrow -5
Chipping Sparrow -3
Congratulations to the 25 of 33 getting the quiz correct:
Answer: Brewer's Sparrow