Arizona: Red-naped vs. Yellow-bellied Sapsuckers...a learning process

27 October 2011

On 22 October 2011, Chris McCreedy and Michael Lester spent a lot of time studying an odd sapsucker in the Quailway Cottage orchard (Portal, AZ).  I'm sorry to say that I noted this immature-plumaged sapsucker as early as 29 September, but dismissed it after only a glance because it looked very dark overall...and I had a lot other things to do that day!  A renewed itch to put the right name to the right organism has now forced me to take a closer look...  Turns out, these two species are more variable than many of us ever thought!  The main resource for this ID issue is a pioneering article published in the November/December 2006 issue of Birding magazine, titled "Variation in Red-naped and Yellow-bellied Sapsuckers." 

On almost any given day in the fall or winter in Arizona, you could probably glimpse a sapsucker and just say "Red-naped" - and the odds are, you would be right.  On October 26, however, I walked into that orchard on the Quailway Cottage grounds and encountered no fewer than 5 individual sapsuckers.  At least two were fully adult male Red-naped Sapsuckers (RNSA); a third had substantial red in the nape but flew too soon.  The remaining two required far more study.

Here's the bird that Chris reported on 22 October (photos are mine, taken today - click the image to enlarge):



While the Birding article does not tout any single field mark as diagnostic, it does say this: "...Red-naped Sapsuckers lacking red on the nape between October 1 and May 1 would be exceptionally unusual, if such occur at all."  So, any Sphyrapicus species without red in the nape seems virtually guaranteed to be a Yellow-bellied (YBSA), regardless of age or sex.  Note that there is no red in the nape of this bird.  Nor is there any red in the nape of the next bird I photographed:



(I'll refer to the first bird as YBSA-1 and the latter as YBSA-2.)  YBSA-1 is clearly a bird in immature plumage.  Multiple resources claim that hatch year (HY) YBSA begin their molt on the summer grounds, "usually" suspend it during migration, and finish that molt on the wintering grounds.  HY RNSA is supposed to molt primarily on the summer grounds, with juvenal head and body feathers "usually" fully replaced by October/November.  So, YBSA-1 seems more-or-less clearcut (despite my inadequate first observation): no red in the nape + late October + immature plumage = call it a Yellow-bellied Sapsucker.  Aside from the nape, there are a few more supporting features visible on this bird: buttery color to the upper back feathers, and some butter-colored spangling in the crown.  I always thought that immature YBSA were supposed to be buffy and lighter brown throughout, and also were supposed to have a lighter crown overall.  Some do - but not all, apparently!  The back pattern also appears somewhat "messy" like a traditional YBSA, but this feature is allegedly variable enough that it's only a supporting mark, at best.

YBSA-2 is a bit more complex.  At first glance, I might have thought that this was an adult bird and immediately called out RNSA, but closer examination shows the lack of fully adult throat/breast feathers (note that the throat frame isn't complete and the breast feathers haven't turned to solid black yet.)  I also thought at first that perhaps it was too far along in its molt to possibly be a YBSA - but the Birding article shows us a museum specimen that is just as advanced (or more so), collected October 11, 1982 in Baltimore.  So it may not be fully adult-plumaged, but it's darn close, and apparently it's not unprecedented.  Additionally, examples of delayed molt in RNSA are extremely difficult to find.

Looking closer still, I tried to judge what little is present of the throat frame:






It's difficult to gauge, to be sure.  However, by the time this bird has all of its adult feathers in place, it looks as though it will develop a solid black frame around the throat, containing the red throat feathers.  It may turn out that some of that red will end up "invading" the black throat frame, but there's no way to tell for at least another month.  While there are a very few YBSA specimens out there with some red extending into the throat frame, RNSA is the species that is well known to have a very broken throat frame completely invaded by red from the throat.  So...we may have to entertain the notion of "hybrid," but the bird at least has some YBSA blood and may yet prove to be a pure-blooded bird.  Or, it could totally surprise all of us and start to spontaneously develop some red feathers in the nape...now that would be worth documenting!

If you haven't given it a thorough read, I highly recommend the Nov/Dec 2006 "Birding" article.  It seems that a significant number of specimens were analyzed, not only by the three authors (Mlodinow, Barry and Cox) but also by a number of other researchers whose work they cite.  It doesn't claim to be the final word on this ID challenge, but it's certainly my go-to reference for the moment.

I'll keep my fingers crossed that these birds stick around, since I live on-site as manager of the Quailway Cottage.  If they stay, I'll be sure to take more photos as the season progresses and see if I can't reach some more solid conclusions!

Happy studying,
John Yerger
Portal, AZ
john@adventurebirding.com
----------
Adventure Birding Company
Specializing in flexible, personalized guiding in SE Arizona
www.adventurebirding.com
520-495-0229

No comments: