Quiz #361 (2010-3-06) Solution

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Answer by Tony Leukering

All respondents got this week's quiz birds to the right genus, but none got the correct answer; somewhat disappointing. Our birds were obviously Plegadis ibis and those dark eyes and dark legs are key characters pointing to Glossy Ibis, which was the species promulgated by the majority of respondents. However, those characters also match White-faced Ibis, at least at some times.

Both of the birds sport anomalous patches of white on the neck and/or head, a feature at odds with both submitted IDs. At least, of identification of birds older than a few months. Yes, the oddly-patterned bills and the white patches on the necks support the contention by many respondents that these are juvenile ibis. Adding more certainty to that age assumption are the fresh, unworn, and even-aged flight feathers. Even though multiple folks noted this feature in our quiz, the age of our quiz birds seemed not to cause much in the way of caution in respondents. There was something of a geographic bias in responses, with all easterners (those living east of the Mississippi River) going for Glossy Ibis and the only votes for White-faced coming from westerners. Interesting to me, multiple respondents provided both species in their answers.

As noted in most (if not all) field guides to "North American" birds, juvenile dark ibis are indistinguishable. While there may be some characters that may suggest one or the other of the two species, as far as I'm aware (and I've looked at a LOT of juvenile ibis), there are no certain separators of the two, thus the correct answer, and one that I hope would be practiced in the field, is "Plegadis sp."

I took this picture of two juvenile dark ibis in July in some U.S. state in which I've lived at that time of year. Of course, that is a considerable number of places, and includes the following states (listed alphabetically): CA, CO, CT, GA, MI, NH, NJ, NY, and OH. White-faced Ibis breeds in two of those, Glossy in four (CT?), and neither in three. One can see the dilemna. If I took this picture in Michigan or Ohio, where both species are rarities, how would I back up any specific ID to the state's records committee? As I have seen breeding-season individuals of one species in two states in which the other species breeds, but which the first is not known to breed and in which the non-breeding species is a rarity, again, how do I back up any ID? Do I let them go in CO and NJ as simply the locally-breeding species, when I have no solid evidence of such, other than location? Why do that? Finally, how do I rule out the possibility of a hybrid, of which I've seen a fair few in CO, a state just south of Wyoming in which both species have bred or do breed?

Birding is more than simply slapping a label onto any given target. At least, I want it to be. That name should not be the end-all, be-all of birding, but simply a way to organize the chaos that is inherent in all biology. It is incumbent upon all of us, I think, to refrain from identifying something definitively, if there is no reason for that definitiveness. We can learn so much more, if our minds remain open to new things, novel theses, rather than simply slapping a name on an unidentifiable bird and moving on to the next. We should not be afraid to let a bird go unidentified.

Okay, I'm done with the philosophizing, let's check out the next quiz!

Incorrect species provided as answers:
Glossy Ibis - 13
White-faced Ibis - 4

All 14 answers submitted were considered incorrect.

Answer: Plegadis sp.

Quiz #360 (2010-3-05) Solution

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Answer by Tony Leukering

Steve Mlodinow, Steve's girlfriend (sorry, my old mind has forgotten her name), Larry Semo, and I were birding the very flooded Tamarack Ranch SWA, Logan Co., CO, on 19 June 2010 when Steve's girlfriend noted a high-flying raptor circling overhead. Due to the height, intervening trees, and the plumage state of the bird, we had a bit of trouble identifying it immediately, but we eventually all agreed that it was....

Ah, I get ahead of myself.

Raptors soaring lazily overhead are usually considerably easier to ID than are raptors screaming by partially tucked. But, this week's lazily soaring raptor caused our respondents fits, as illustrated by the fact that the correct answer was not the most frequent answer provided - a rare occurrence in the Mr. Bill Mystery Quiz. Our bird's plumage, well, let's just say that it's seen better days. With the date given, things get a bit easier, as a ragged bird at that time of year is almost certainly a first-cycle bird (right around one year old), but the date was not provided for the quiz, so we'll have to go on without that datum.

The dark flight feathers, white underwings, mostly-white body, and black wrist mark leave few options, with all the best ones provided as answers this week: Osprey, Swainson's Hawk, and Short-tailed Hawk. While Prairie Falcon is variable as to its underwing pattern, but they also show at least dark axillars and it and Gyrfalcon never show a distinct dark patch on the greater primary coverts on the underwing. White-tailed Hawk is somewhat of a match for parts of our bird, but as the outer pair of rectrices on both sides of the tail are complete and there is no sign of the distinct black subterminal band typical of adults of that species, adult White-tailed is eliminated; juveniles would never be so pale.

Our bird's 6th primary (p6; count 5 primaries in from the outermost) is considerably and noticeably shorter than is p7, creating a very pointed look to the wingtip for a buteo, so Short-tailed Hawk is ruled out. Osprey sports a wrist patch, not just a comma, with the length of all the greater primary coverts on the underwing being dark, not sporting a terminal bar. Additionally, Osprey does not exhibit the dark of the face extending down to the shoulder and onto the throat as does our quiz bird. Thus, by the process of elimination, our quiz bird is a Swainson's Hawk. Colorado plays host to, well, hosts of such birds in summer, and birders with little experience with them in the field often believe that they're other species, because they just don't look like the pictures in the books! But, our quiz bird is identifiable as a Swainson's Hawk by the various features presented above: dark remiges contrasting with pale wing linings, wrist comma, no carpal bar, pointed wingtip, dark extending from auriculars to sides of throat, and pale tail with vague darker bands.

This week's quiz picture was the fourth consecutive one from northeast Colorado on 19 June, illustrating quite nicely how easy it is to take quiz pictures! With the wreckage caused by this quiz, Tyler Bell, Chuck Carlson, and Joel Such are the only players remaining with perfect scores after five quizzes.

Incorrect species provided as answers:
Short-tailed Hawk - 2
Osprey - 8
Prairie Falcon - 1
White-tailed Hawk - 1

Congratulations to the 6 of 18 getting the quiz correct:
Tyler Bell
Chuck Carlson
Margaret Smith
Margie Joy
Jim Beatty
Joel Such

Answer: Swainson's Hawk