Monday, June 22, 2009
Quiz #305 (2009-2-13) Answer
Click the picture for a larger view.
The photograph was not taken within 250 miles of the Pacific Ocean..
Answer by Tony Leukering
Ouch! This week's quiz bird is a member of the genus Corvus and with no sound nor flight style to use for ID, it's a hard one. We should first decide whether 'tis a raven or a crow. The shortish and fairly squared tail rules out most individuals of the two ABA-area raven species, as does the fairly short bill. While some may complain that separating the four ABA-area crow species is very difficult, I think that it's considerably easier than raven ID! Besides, we do have the red-text caveat that the bird is not a Northwestern Crow (regardless of what that taxon really is), so buck up and read on. Despite the difficulty, a plurality of respondents did go for the correct answer.
Those that play both of the online photo quizzes that I run may have an advantage in this quiz's solution; you may wish to refer to the picture in the June 2009 ABA online quiz (aba.org/photoquiz/). One might do that because the two pictures ran concurrently for a week and they're both of crows! So, what's a responsible respondent to do, think that they're both the same species (which many know would not be at all beyond me) or randomly pick two species and guess one for each or should s/he buckle down and learn how to distinguish crows in flight. As I consider these quizzes as education venues, I'll be running us through the last of these three options.
So, we've got three species to consider: American, Fish, and Tamaulipas. As one respondent noted, it's a good thing that Sinaloa Crow (formerly part of Mexican Crow until the split creating Tamaulipas and Sinaloa crows) does not occur in the ABA area. Yet. They're quite similar, being lanky, glossy crows of coastal (and near-coastal) areas that almost certainly share a fairly recent common ancestor. In fact, Tamaulipas may be the easiest species to exclude, as our quiz bird is too chunky; too wide-winged; and, perhaps, too short-tailed for that taxon. I could not run down on the internet any pictures of the species in flight -- none in the VIREO collection and none on Flickr! Doesn't anyone have such? Despite this, my recollection of the species is of a long, lanky, narrow-winged, long-tailed crow that is quite different (in a subtle, crow-kind-of-way) from the other crows with which I am familiar.
As many ABA-area birders live in or near areas with both American and Fish crows, it ought to behoove them to learn their salient ID characters. However, from personal experience, I know that many birders believe that they're not identifiable without vocal cues (having even heard a field-trip leader in NJ say this to participants!). While ID may be difficult, it is in no way impossible without vocal cues. Proportions of wing length and tail length are useful (and were the cues that I used in my first stint living on the East Coast way back when). However, Michael O'Brien, who edited the text and artwork of the most recent edition of the venerable Peterson guide, put me onto another character that is more sure and doesn't require a lot of experience in judging wing and tail proportions of the two species. It is also one that he made sure to illustrate properly in the new Peterson guide (white cover with flicker). In fact, despite considering one-character ID suites anathema, I'm going to head down that road with this set of two crows.
What we need do, is study the wing formulae of the two birds. American Crow has more fingers -- and longer fingers -- than does Fish Crow ('fingers' being outer primaries, the tips of which are visibly separate from their neighbors on the spread wing, not cheek-to-jowl like the inner primaries and secondaries). Knowing that crows have ten primaries (as do all of the first half (or so) of the passerines) and counting backward from the outermost primary (primary #10; p10), one can see that p5 is quite distinct (thus, a finger) and is considerably longer than is p4, yet still noticeably shorter than is p6. On the ABA quiz crow, however, p5 is just a bit shorter than is p6 and just a bit longer than (and with its tip nearly adjacent to that of) p4. While one might think that this would be an impossible difference to discern in a flying crow, it's not actually all that difficult -- crows flap their wings at a relatively slow speed -- but does require at least reasonable views of the bird in question.
Now that we all know this difference between American and Fish crows, we all know that this week's quiz bird is an American Crow (whose picture I took 22 October 2008 at Cape May Point, Cape May Co., NJ).
With this quiz being the 13th and final quiz for the quarter, it's time to see who the winner is! Aaron Brees outlasted all other respondents and takes this quarter's prize (see the rules) by scoring 11 of 13 correct. Congrats, Aaron! The runners-up were Bryan Guarente, Mark Dettling, and Marcel Such.
Fish Crow - 6
Common Raven - 1
Tamaulipas Crow - 3
Red-winged Blackbird - 1
The 7 of 18 providing the correct answer:
Answer: American Crow