Monday, October 31, 2011

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