Yellow-bellied Sapsucker molt progression

During the winter of 2011-2012, I had the opportunity to study a Yellow-bellied Sapsucker that frequented the small apple/pecan orchard in my yard.  Unfortunately, not being the most skilled photographer, I'm limited in my ability to present the bird from the same angles throughout the season!  Still, I think I did well enough to show some sort of molt progression.

We'll start with the original plumage and work our way up to current.

Late October, 2011:

Hatch Year (HY) Yellow-bellied Sapsuckers undergo a much more protracted molt than do HY Red-naped Sapsuckers.  Given a choice between Yellow-bellied and Red-naped after September, any individual with juvenile head plumage is most likely a Yellow-bellied (Pyle 1997).

This bird clearly does not look like an adult bird.  The overall face pattern is only vaguely defined.  Crown still has much gold spotting; upper chest shows only a hint of the black pattern that will develop as the bird molts.  Throat frame is incomplete, so much so that it could be confused with a Red-naped Sapsucker, except that no Red-naped should show this much retained juvenile plumage by October.  To further validate this, our next photo is a dorsal view.

This photo shows the classic immature Yellow-bellied back pattern: a messy array of buttery-colored markings.  Importantly, there is no red in the nape.  After October 1, it is very unlikely that any Red-naped would lack visible red in the nape (Birding magazine, Nov/Dec 2006).


Late November, 2011:

In just one short month, the bird has already developed quite a bit!

In this photo, one can see that the face pattern has become much more defined.  The throat frame is much blacker and more complete, neatly encircling the red throat feathers (which have also become vibrant and filled in more).  Even with the shadows that are falling across much of the body, the bird still shows a bit more black feathering in the upper chest and darker black in the post-ocular area leading back to the stripe that borders the nape.  There is still much retained gold spotting in the forecrown, but the rear crown has become blacker with the rest of the plumage.  Not much to see in the nape, but still no red!  A good sign...


Early March, 2012:

In this photo, the bird looks essentially like an adult.  It is more obvious that this bird is a male, with now-complete red throat and full black throat frame.  The forehead now has quite a bit of red as well, which can be seen better in the next photo.  Essentially, almost all of the head plumage has been replaced.

More of a ventral angle.  Note the extensive red in the forehead extending back through the crown, but even still there is some retained gold spotting/scalloping.  No red from the throat crosses the black throat frame, which is a mark one would expect on a Red-naped.

Just to confirm, still no red in the nape!  Much of the back feathering is a crisper black than before.  The buttery spots appear to be in neater rows in this image, which is more in line with Red-naped back pattern (except the coloring would be whiter, not buttery).  Back pattern has proven to be one of the less reliable field marks on these two Sapsuckers.  Head pattern, especially lack of red in the nape after October 1, seems to be the most reliable.  And I won't muddy these waters with talk of hybrids...that's outside the scope of this blog post!


Hope that helps anyone trying to distinguish young Yellow-bellied from Red-naped Sapsuckers next winter!

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


References:


Mlodinow, Steven G., Jessie H. Barry, and Cameron D. Cox. 2006. Variation in Red-naped and Yellow-bellied Sapsuckers. Birding 38:6 42-51.
Pyle, Peter.  1997. Identification Guide to North American Birds. Part I.  Slate Creek Press, Bolinas, CA.

1 comment:

Rory said...

Very interesting! Sounds like it was quite a treat to monitor his progression.
You've taken some nice photos. I enjoyed that.
Thanks.