Monday, August 8, 2011
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Solution by Bryan Guarente and Tony Leukering
Bryan Guarente supplied a good answer, so I'll start with that.
"In a Birding photo quiz, our CFO quizmaster has gone over what I think is this set of confusing juvenile sparrows. The bird is a sparrow as indicated by the pink legs, longish tail, and generally brownish tones. It is a juvenile as indicated by the streaking on the chest. The crispness of the streaking also lends one to believe this is an early-season bird. The Spizella sparrows (Chipping, Clay-colored, and Brewer's) and Cassin's Sparrow seem to fit the bill, as is mentioned in the solution from Leukering's Birding photo quiz answer.
Cassin's Sparrow would have a rounded tail unlike our bird's notched tail (note the central tail feathers are shorter than the outer tail feathers). It would also sport large dark centers on the scapulars which our quiz bird does not sport. We're down to the three options.
"By habitat, one might expect this to be Chipping Sparrow with a lesser probability of Clay-colored Sparrow. Brewer's seems to choose sagebrush or low willows above treeline depending on the subspecies. This oak microhabitat is at odds with the normal habitat of Brewer's so I may be willing to drop that, but I think there is more to go on. I was hoping I could go farther and find out that the oak in the picture is one of an eastern species, but to my chagrin, I believe it is a Gambel Oak (Quercus gambelli), the only lobed oak native to the southern Rocky Mountains. That didn't seem to help much and put me back in the Brewer's Sparrow and Chipping Sparrow hole, due to range considerations.
"The overall colors on our quiz bird are rather bright. This is not necessarily due to photographic effects since some of the leaves are overexposed which would make one expect the bird to be overexposed as well dulling the colors. Clay-colored and Brewer's both typically show duller colors than our quiz bird which shows bright reddish brown tones, which seems to point again to Chipping Sparrow. The eye stripe is rather dark which is said to be good for Chipping Sparrow, but I am uncomfortable with that since the rest of the facial pattern doesn't seem to show the markings I would expect of a juvenile Chipping Sparrow.
"At this point, I usually have found a solution to the problem and can give a solid answer. This time, I am hopping all over the place. Should I just go with Spizella and leave it at that? Why is it such a struggle to just leave a bird as unidentified?
"I think about what I am doing to identify this bird and find myself weighing the identification characteristics that I have already mentioned. The notched tail, chest streaking, and facial and crown pattern should put this bird squarely in Spizella. After that, I feel like the color of the bird sticks out as the most important factor. The eye stripe is, to a lesser extent, important. The habitat can always be tricky, seeing as Chipping Sparrows are migrating now through the state and can seemingly be anywhere, habitat-wise. I don't have as much experience with Brewer's and Clay-colored on migration, but assume (yeah there is that word) they act similarly, migrating early and working all sorts of different habitats."
Thanks, Bryan, for showing us all that hunches can play a part in correct identifications, but only with experience. The eyeline, however, is one of the key features to get us to the correct ID of Chipping Sparrow, once we've gotten into Spizella, that is. It really does eliminate all congeners. American Tree Sparrow is ruled out by the presence of oak in the picture, as that species molts out of first basic (=juvenal) plumage before migration. Additionally, one would be hard-pressed to find a juvenal-plumaged American Tree Sparrow in a green- and lobe-leaved oak, much less a Gambel Oak. Finally, the quiz subject sports rufous-fringed scaps that similarly-plumaged Vesper Sparrows don't have and even juvenal-plumaged Vesper Sparrows exhibit a more complex facial pattern than shown by our quiz bird. Glenn Walbek took this picture of a juvenal-plumaged Chipping Sparrow in Castle Rock, Douglas Co., CO, in July 2007.
With just about half the quarter gone, Robert McNab, Diane Porter, and Marcel Such are tied at the top of the leader board with perfect 6-for-6 scores.
Incorrect species provided as answers:
White-crowned Sparrow - 1
American Tree Sparrow 2
Vesper Sparrow - 3
Brewer's Sparrow - 1
Dark-eyed Junco - 1
Congratulations to the 11 of 19 getting the quiz correct:
Answer: Chipping Sparrow