Date: 2/23/17 4:42 pm
From: Nels Nelson <nelsnelson7...>
Subject: [obol] Re: More thoughtson the Bingen goldeneye.

Here's a little montage of goldeneye photos I took 2-7-17 (at the So.
Jetty, Newport) of Common and Barrow's Goldeneye (with a couple possible
hybrids). I was puzzled by the two individuals with different white spots,
but hadn't given much thought about hybrids between the two species (until
Wayne's lovely all black-headed individual showed up).

Nels Nelson

On Thu, Feb 23, 2017 at 3:41 PM, Wayne Hoffman <whoffman...> wrote:

> Hi -
> First, a quick summary of what I see in my photos.
> 1. The head does not seem to be in molt.
> 2. No sign whatsoever of a white medallion, crescent, or intermediate
> mark.
> 3. The head was less iridescent than typical of either Common or
> Barrow's. Some photos showed a little iridescence, not green nor
> blue-purple, but maroon to reddish purple. [Maroon is typical of Common X
> Barrow's hybrids.]
> 4. Head shape is higher-peaked than typical for Common, a bit more like
> Barrow's.
> 5. The bill seems smallish for Common, more like Barrow's, but not an
> easy call.
> 6 The body/wing plumage, as seen on the swimming bird, appears to be
> either full adult, or nearly there.
> 7. The inner secondaries were a bit ruffled or disturbed. They seem to
> show a bit more black than typical for a Common, but much less than on
> Barrow's, or on F1 hybrids.
> 8. No sign of the Black spur that Barrow's has separating breast from
> flanks.
> 9. On both species the white panel of the flanks ends near the legs and
> the rear flanks and under-tail coverts are black.the boundary between the
> two is slanted, such that the whit extends further posteriorly at the top
> than at the water line. The angle of this boundary differs between the
> species, especially when swimming high in the water. On Common the
> boundary is sharply slanted, often more than 45 degrees from vertical, and
> on Barrow's it is closer to vertical. on the Bingen bird it is somewhat
> intermediate, but more like Barrow's.
> Possible explanations:
> A. Possibly this is a young bird that has completed or nearly completed
> its body feather molt but has skipped the head molt. This seems unlikely
> because the head plumage does not seem worn or faded, and does not seem to
> be the female-like brown shade of immatures.
> B. Possibly this is a hybrid Common X Barrow's. The lack of facial white
> aside, this bird looks a bit more like a Common X Barrow's Goldeneye than
> either of the species. Normally these hybrids have a white facial mark that
> is pear-shaped - essentially the white medallion of a Common pulled up into
> a point in front of the eye. The upper-wing pattern looks more like
> Common, but most of the other features seem to show Barrow's influence.
> C. Possibly this is a hybrid Goldeneye X something else? The main
> problem with this is that no other parental traits are obvious. Birds
> identified as Goldeneye X Bufflehead hybrids tend to have extensive areas
> of white on the sides of the face. Interestingly, birds identified as
> Goldeneye X Hooded Merganser hybrids have dark heads lacking both the white
> medallion or crescent of the goldeneye, and the white crown (some have a
> few .smll white patches near thier eyes). Evidently each parent provides
> genes blocking the expression of the other species' white marks. However,
> these hybrids tend to have larger, rounded heads, and also show the dark
> arcs separating the breast from the flanks of the merganser parent. They
> also tend to have longer, lower-profile bills.
> D. Possibly this is "just" a Common Goldeneye lacking the medallion.
> Possibly, but the other features noted above tend to show differences
> suggesting also Barrow's influence.
> Thoughts?

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