Quiz #385 (2011-1-06) Solution

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Answer by Peter Wilkinson and Tony Leukering

As on last week's quiz, one of the regular respondents provided a good rationale for his ID, so we'll start with Peter Wilkinson's words.

"Aha! We have a dark-backed, large white-headed gull (LWHG) with yellow legs. The yellow legs rule out Great Black-backed, Slaty-backed, and the darker Western (wymani) gulls, as all have legs of varying shades of pink. The LWHGs with yellow legs, or at least yellowish legs, on the ABA list are Yellow-footed, Lesser Black-backed, and Kelp gulls, and, perhaps arguably, Yellow-legged Gull, which just about gets to the paler end of Lesser Black-backed but not really as dark as this. This is clearly a heavy-set bird, with a large and deep bill; Lesser Black-backs, though they match the colour of the back (apart from graellsii, which is paler than this), simply don't match the build. Kelp Gull has greenish rather than bright yellow legs.

So, we are left with Yellow-footed, which appears to fill the bill. It is difficult to be sure from the photograph, but the color of the orbital ring appears also to support an ID of Yellow-footed. LWHGs are, of course, a bit of a minefield, where even experts sometimes have to agree to differ, but there does not seem to be any reason not to believe that this individual is identifiable, and no reason to start thinking of hybrid origin."

What Peter didn't specify is the color of the orbital ring on our quiz bird. As this can be a crucial ID feature, it is incumbent upon us to get this right, particularly as it can be a tricky feature to assess correctly in the field, to say nothing of a digital photograph. At least, though, the bird isn't moving its head around making it even more difficult. The picture below is extracted from the quiz picture and shows the bird's yellow orbital ring -- the same color as the bill, which is different from the red of Great Black-backed, the orange of Kelp, and the orange-yellow of western.


The very heavy bill, orbital-ring color, and the obvious skirt (for a refresher on skirts, see Mr. Bill Mystery Quiz #335 one year ago), among other features, rule out Lesser Black-backed Gull.

Of course, had you been standing with me when I took this picture at Puerto Peñasco, Sonora, Mexico, on 21 February 2006, you would have been able to be pretty sure of the ID of Yellow-footed Gull just on the location!

Incorrect species provided as answers:
Lesser Black-backed Gull - 6
Kelp Gull - 1

Congratulations to the 24 of 31 getting the quiz correct:
Tyler Bell
Brandon Percival
Nick Komar
Ben Coulter
Devich Farbotnik
Peter Wilkinson
Jim Beatty
Pam Myers
Christian Nunes
George Cresswell
Ali Iyoob
Chuck Carlson
Barbara Deneen
Robert McNab
Joel Such
Al Guarente
Nick Moore
Marcel Such
Christopher Hinkle
Adrian Hinkle
Tucker Lutter
Su Snyder
Joe Bens
Bryan Guarente

Answer: Yellow-footed Gull

Quiz #384 (2011-1-05) Solution

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Answer by Bryan Guarente and Tony Leukering

Brian Guarente provided a good response, so we'll start this week's solution with his words.

"Okay, you had me for a second.... I thought it was a Black Tern, but, thankfully, so much looked wrong on initial glance that I didn't submit right away. I needed to spend more time looking and it became obvious that this is not a tern at all. The feet are the best clue to make sure that this isn't a member of the Laridae: No webbing.

"So, where do we go with this? The feet look like that of a perching bird, not that of a wader or swimmer, so to the back half of the book we go. A mostly BLACK bird with a white underside gives us five options: Eastern Kingbird, Fork-tailed Flycatcher, Black Phoebe, Tree Swallow, and Dark-eyed (Slate-colored) Junco. Eastern Kingbird and Fork-tailed Flycatcher show white in the face, not just on the underside and underwings. Tree Swallow's tail is much shorter than this and the wings are more pointed. Slate-colored Junco is not this black and the bill is all pink, but the rest of the pattern matches very nicely, which I found an interesting similarity. This leaves only Black Phoebe."

Though some might be quite surprised by the two submissions of Brown Jay, one of the correct respondents noted that his first thought upon looking at the picture was Brown Jay. As one of the incorrect respondents noted, juvenile Brown Jays have yellow bills and their plumage pattern is fairly similar to that of our quiz bird. But, that same respondent noted, our bird's bill is actually yellow only on the inside; it is otherwise black. Eastern Phoebe can be ruled out by the darkness of the dark plumage and the extent of white on the outer web of the outermost rectrix (Black shows a nearly entire white outer web, while Eastern generally has only the basal half of that web white. Another consideration is Black x Eastern Phoebe hybrid, a combo that is turning up more and more with Black Phoebe's rapid range expansion in Colorado and New Mexico. Nathan Pieplow, Elaine Coley, and I published a paper in Western Birds on the first confirmed occurrence of this hybrid in Loveland, CO, a couple years back, and more instances have been found in both Colorado and New Mexico since. That combo can be ruled out by the same characters that eliminate Eastern Phoebe from consideration, though with more care being required. A picture of the Loveland bird can be found on my photo site.

Bill Maynard took this spectacular photo of a Black Phoebe along the Arkansas River in Pueblo, Pueblo Co., CO, on 7 January 2011.

Incorrect species provided as answers:
Brown Jay - 2
Eastern Phoebe - 1

Congratulations to the 26 of 29 getting the quiz correct:
Pam Myers
Robert McNab
Chuck Carlson
Clare Mix
Ben Coulter
Christopher Hinkle
Brandon Percival
Devich Farbotnik
Bryan Guarente
Al Guarente
Nick Komar
Jim Beatty
Ira Sanders
Tammy Sanders
Buzz Schaumberg
Margie Joy
Adrian Hinkle
Thomas Hall
Margaret Smith
Kirk Huffstater
Matt Bristol
Tucker Lutter
Peter Wilkinson
Chishun Kwong
Joel Such
Marcel Such

Answer: Black Phoebe