[Tweeters] Williamson's Sapsucker -- abnormal plumage one side
Devorah the Ornithologist
birdologist at gmail.com
Sat Mar 5 04:28:50 PST 2016
this bird MAY be a chimaera between twins that developed inside the egg.
one of those twins may have had the genetics for a melanistic colour morph,
and when the two twins fused into one being at an early developmental stage
(by or after the 2-cell stage, and by or before the 128-cell stage, as i
understand this phenomenon), they could have formed a bilateral chimaera
such as what it appears you are seeing in that photo.
i say "may" because bilateral chimaeras are unusual (but not unheard of!).
a bilateral gynandromorph is a special sort of chimaera that forms between
male and female twins that fuse at an early stage of development. not all
bilateral chimaeras are the product of opposite sex twins, and thus, it is
possible this phenomenon is more common than we think, even in humans.
On Sat, Mar 5, 2016 at 6:00 AM, Jeff Kozma <jcr_5105 at charter.net> wrote:
> It looks to me that the Williamson’s Sapsucker you photographed/videoed
> looks like it might have a plumage abnormality where the side feathers that
> are black/barred/streaked with white have formed along the belly, as well
> in a bilateral pattern, where it only occurs on the birds right side. This
> could be a case of bilateral melanism where the side/belly feathers on the
> right side are darkened abnormally. >From the photo and video, it looks
> like a normal male WISA except for this darkened streaking pattern on the
> right side and belly. My guess would be bilateral melanism.
> Because of the bilateral nature, I first thought it was gynandromorphy, a
> bird showing both male and female characteristics because this condition
> occurs bilaterally. But, this bird doesn’t show any female plumage
> I don’t think this bird is a hybrid, as evidence of hybridization through
> plumage usually isn’t confined to a specific area. There is generally an
> overall mix up of plumage characteristics between the two species that
> crossed and in my experience isn’t confined to one side of the body.
> Other than some sort of melanistic condition occurring only on the right
> side (melanism and leucism often occur patchily or in non-patterns), I’m
> Jeff Kozma
> *From:* tweeters-bounces at mailman1.u.washington.edu [mailto:
> tweeters-bounces at mailman1.u.washington.edu] *On Behalf Of *Kevin Lucas
> *Sent:* Friday, March 4, 2016 8:55 PM
> *To:* TWEETERS <tweeters at u.washington.edu>
> *Subject:* [Tweeters] Williamson's Sapsucker -- abnormal plumage one side
> Williamson's Sapsucker half-normal plumage
> My reward for a nice long hike in the snow today was a Williamson's
> Sapsucker (WISA) that had yellow only on the left side of its breast. On
> its center and right breast were black and white markings -- not the black
> with white wisps I usually see on adult males' breast sides. Its
> vocalizations and drumming were typical for WISA, and it was calling and
> drumming with two or maybe three other WISA. In March of previous years
> I've photographed WISA with unusual black markings in what is usually a
> solid white wing patch, but this seems like something different is
> happening -- where plumage on just one side is wacky.
> Can anyone provide me with information on what causes this one side color
> abnormality, and whether there's a term for it? So far my Google searches
> have landed on albinism and leucism. Maybe it has something to do with
> I posted a still image frame capture from a movie, along with a movie in
> which you can hear the characteristic WISA drumming. I apologize for the
> image shake (superzoom hand held in the cold).
> Here are links to the still photo
> and to the movie clip
> on my Flickr photostream.
> Kevin Lucas
> Selah, WA
> <a href="https://www.aba.org/about/ethics.html" rel="nofollow">Birding
> Tweeters mailing list
> Tweeters at u.washington.edu
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Devorah Bennu, PhD
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