There are other features indicating hybridization with Common Goldeneye.

If you look in Sibley, he labels the ?black spur? that droops to the forward end of the scapular spot region. Compare that to Common Goldeneye, which has a forward-pointing horizontal spike. Your green-headed goldeneye shows both the drooping black spur and the horizontal spike. The spur also looks slightly ?funny? ? a bit too blunt and a bit too short to be pure Common.

If you look at the rear section of the black side patch, there seems to be a similar difference. A male Barrow?s Goldeneye should have a strong black bar angling slightly downward connecting the scapular patch to the black rump. A Common Goldeneye should have just a thin, horizontal black thread. Your green-head shows much closer to the horizontal black thread.

Additionally, it?s not totally apparent, but it seems to me that the facial crescent doesn?t quite reach to a sharp point at the top ? just a touch rounded up there perhaps.

So it seems clear to me that this bird is, indeed, a hybrid. Maybe the fact that it appears different from ?typical? hybrids indicates that it is a back-cross bird.

Very interesting. This was very much like the ?Find 6 differences between the pictures? from the Seattle Times comics page...

== Michael Hobbs
== Kirkland, WA
== http://www.marymoor.org/birding.htm
== http://www.marymoor.org/BirdBlog.htm
== birdmarymoor at frontier.com

From: Pterodroma at aol.com
Sent: Wednesday, March 07, 2012 5:32 AM
To: mcallisters4 at comcast.net ; tweeters at u.washington.edu
Subject: [Tweeters] Re: Barrows Goldeneye with green head sheen

Wow, fascinating photo capture there Kelly, very striking with both goldeneyes comparatively in perfect or near perfect juxtaposition relative to each other and to lighting that 'might' otherwise alter perception of sheen. In this case even if that juxtaposition is ever so slightly 'off', casting one head to the light one way, the other, another, it doesn't appear to me to be enough to make such a striking difference as exhibited in your image. Plus, it sounds like you didn't notice this feature on any of all the other Barrow's Goldeneyes assembled and am guessing you probably put in some time and effort consciously searching for such given this one individual was such a 'stand out' in the crowd.

One thing I do notice is that the scapular spots are slightly larger on the 'green' headed bird, smaller in the 'purple' head and more typical or closer to average amongst Barrow's. Common Goldeneyes have much more white in the scapulars of course. However, the scapular spots shown on both birds in your image still lean to looking like 'spots' as opposed to something vastly more extensively white and this may not be a point to even argue at all given natural variation among individuals. So, you might have something curiously interesting there, curious anyway no matter how you slice it, and it may well have some genes of some 'ancient' Common Goldeneye ancestry as you tossed out for our rumination.

Richard Rowlett
Bellevue (Eastgate), WA


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