Quiz #423 (2011-4-05) Solution

Click on picture(s) for a larger view.


Solution by Tony Leukering

Yes, it's an oddity and was a nice learning experience for me! It was obvious to respondents that the quiz bird is a member of one of the Centurus woodpecker species. (Quick note: Centurus used to house all of the zebra-backed woodpeckers, and was the genus I learned when I started birding, until that genus was lumped into Melanerpes, though the term is still quite useful in separating the zebra-backed species from the other members of that genus, all ABA-area members of which are quite different: Lewis's, Acorn, and Red-headed woodpeckers.) However, the quiz bird's odd head pattern, in combination with our inability to see the bird's rump provided much cause for consternation.

First off, as with many birds, we might be best served by ageing the thing at the outset. While the primaries look paler than black, I would be leery of going out on that limb to support the contention that the bird is a youngster, due to questions of lighting and the fact that we can see them all that well. However, we don't have to go there, because the head provides all we need to age the bird. None of the Centurus woodpecker species sport any black on the crown in anything but juvenal (=first basic) plumage, and that black is rare enough even in that plumage.

Because this bird is sporting odd head coloration and pattern, we should really check out the other useful bits to see if they'll be helpful. Of course, at this point, we can really bemoan the lack of view of the rump, as the three ABA-area Centurus species are readily differentiated on the strength of just that one feature. However, we only need to look a bit lower down to find a very useful feature: the tail rules out Golden-fronted Woodpecker. Or, at least, rules out the form of Golden-fronted that occurs in the ABA area (some subspecies in Mexico have banded middle rectrices). Hmm, then why is there yellow on the bird's nape and red on the crown? But if it were a Golden-fronted, why aren't the nasal tufts yellow? Could this be a hybrid?

Recall that some juveniles -- of both sexes -- of other species of woodpeckers (particularly Downy and Hairy woodpeckers) sport red on the crown, despite the lack of such in older plumages. So, the seemingly-anomalous red on the crown may not be anomalous in juveniles, even in Centurus woodpeckers. Yes, that might bring Golden-fronted back into play, but recall the tail pattern. What we can see of the underparts coloration -- that single bit by the right leg -- looks white, not tan as in Gila.

Now, let's make a more-careful scrutiny of the various barring on this bird, as that is a useful, though subtle, feature in separating the possibilities. The back barring looks as if the black bars are too wide for Gila, possibly even for Golden-fronted. However, the central rectrices have white bands noticeably wider than the black bands, which is good for Red-bellied and wrong for Gila.

In fact, this is a juvenile Red-bellied Woodpecker, photographed 4 Aug 2007 in Lamar, Prowers Co., CO, by Dave Leatherman, to whom I give thanks for recognizing the oddity of the plumage and sending me the picture for possible use here. This individual combines three odd head-plumage traits -- yellow nape, black on crown, red on crown -- that are found singly in a smallish percentage of juveniles of the species. A picture that I found on Flickr shows another juvenal-plumaged Red-bellied with black -- and just a bit of red -- on the crown. The take-home message is once again, pay attention to more field marks, even on readily-ID'ed birds. Knowing the common species cold is the best route to becoming an excellent birder.

Incorrect species provided as answers:
Gila Woodpecker - 4
Golden-fronted x Red-bellied Woodpecker - 1
Golden-fronted Woodpecker - 2

Congratulations to the 17 of 22 getting the quiz correct:
Nick Komar
Margaret Smith
Rudi Nuissl
Devich Farbotnik
Kirk Huffstater
Christian Nunes
Pam Myers
Robert McNab
Margie Joy
Patty McKelvey
Al Guarente
Su Snyder
Thomas Hall
Liston Rice
Peter Wilkinson
Diane Porter
Bryan Guarente
Sean Walters

Answer: Red-bellied Woodpecker

Quiz #422 (2011-4-04) Solution

Click on picture(s) for a larger view.

Solution by Tony Leukering

Usually, when the quiz picture is a difficult one or when there's a gull involved, the number of responses for the week is relatively low. So, one can imagine my surprise at the good number of responses to this week's quiz when not only is there a gull involved, but it's quite difficult! Though it's quite difficult, nearly any ABA-area gull addict would have gotten it correct. But, that is because the important characters are ones that lariphiles know and most birders don't.

We'll start with the individual in the picture that caused very little consternation, the bird of which the image was intended, until the gull flew in front of the camera at Goleta, Santa Barbara Co., CA, 28 February 2010. The seasonality of the picture may very well be determinable from the subjects. The cormorant is in high condition, what with its bright orange supraloral and gular patches. The apparent four-year gull is not molting, at least, not apparently so. Both features are consistent with early spring. And that will come into play with the gull.

As noted by those respondents submitting rationales for their ID decisions, the head pattern on the cormorant is definitive for Double-crested. Neotropic, which can show orange in the supraloral region, never has so extensive a gular patch (it extends past the chin onto the upper throat on our quiz bird). The separation of the bright color by a dark loral line (and the extensive gular patch) rule out Red-faced Cormorant. All the rest of the cormorants have dark bills.

Features that at least some of the respondents used to ID the gull included tail color, bill pattern, darkness of the greater coverts, and (for one) the pale trailing edge to the secondaries. While the bill has an extensive pale base, it is not nearly pale enough nor demarcated enough for a nearly one-year old California Gull. Any Cal Gull with that little pale would be much younger and exhibit extensive juvenal (=first basic) plumage on the upperparts, which our quiz gull does not. Additionally, the greater coverts appear a bit too pale, relative to the darkness of the secondaries and to the median coverts for our bird to be a Cal Gull, which sport greater coverts closer to the color of the secondaries, rather than the median coverts, not the more-intermediate color expressed by the quiz bird. Yes, California Gulls of this age sport a pale trailing edge to the secondaries, but so do a couple other options.

Herring Gull was the overwhelming choice for the ID of the gull, perhaps due to its large range and relative familiarity to most ABA-area birders have with the species. Additionally, the vague dark-and-pale bill pattern is practically perfect for Smithsonian Gulls (the New World form of Herring Gull) of this age. Unfortunately, formative-plumaged Smithsonian Gulls have pale greater coverts that contrast not at all with the median coverts, and very strongly with the secondaries. They also have a pale wing panel, created by the paler inner primaries that are not exhibited by our quiz bird. Finally, they do not sport such a pale trailing edge to the secondaries; at least, not so wide, not so white, and not so obvious.

Thayer's Gulls of this age have nearly entirely black bills and sport secondaries with dark outer webs and pale inner webs, unlike the apparently all-dark secondaries of the quiz bird. Additionally, many Thayer's Gulls of this age are still sporting at least some juvenal feathers among the scapulars; our bird seems not to have any such scaps.

So, as far as big, dark gulls go, we have only two remaining options. Yellow-footed Gull is, despite its size, a three-year gull, thus at this bird's age, it would have a gray saddle. By process of elimination, then, we are left with the correct answer: Western Gull. But, what about the bill pattern? All the field guides show first-winter Western Gulls as having all-dark bills. Well, if you're talking about "regular" field guides, the ones that treat all of the species of a given region, then yes. However, those guides don't have anywhere near enough space to show much of the variation in appearance inherent in any species, nor the various intermediate stages between the appearances that they do illustrate. "Second-winter" Western Gulls are depicted in those guides as having strongly bi-colored bills, and those bills don't just suddenly become that way. As in smithsonianus Herring Gulls, Western Gull bills transition, slowly, from all dark to bi-colored, and this week's quiz gull is somewhere in the middle of that process. And that pale trailing edge? That is what creates the skirt in Pacific-rim gull species.

Gull ID is relatively straightforward (ignoring, for now, hybrids), however it is a more complex game using features that are not part of the ID process for most other taxa (such as wing panels and the obvious pale trailing edge of Cal, Yellow-footed, and Western gulls) and requires a lot of practice and being able to focus on more than just one or two features. I note that one of only two respondents getting this week's quiz correct lives in coastal California, where Western Gull is the gull. The other is a Brit, and we always expect better things out of them!

One response provided only one species, taking a pass on the gull.

Incorrect species provided as answers:
California Gull - 3
Herring Gull - 19
Red-faced Cormorant - 1
Thayer's Gull - 1

Congratulations to the 2 of 26 getting the quiz correct:
Robert McNab
Peter Wilkinson

Answer: Double-crested Cormorant, Western Gull