The gig is up on this quiz. Here is the link to the photo: https://flic.kr/p/ncpq2d
Some other photos of the flock (12 Barrow's, including adult and immature males and females) is here, plus a recent female in silhouette:
https://flic.kr/s/aHsjXvkosK
Here is how you did if you answered:
goldeneyes -- correct!
female goldeneyes -- correct!
mix of female Barrow's and Common Goldeneyes -- correct & extra points
And for those not ducking the subtleties, I salute you--
Mix of adult and immature female Barrow's Goldeneyes with adult female Common Goldeneye and an adult female unidentified goldeneye (center bird 3rd from left). This odd bird could be a Common Goldeneye, and it mostly looks like one, but it shows some characters of Barrow's. More on that bird below following a summary of the identification.
Thanks to everyone for the replies. Great to hear from you all.
Bill color: The character most helpful on female goldeneye has to be bill color because it can be distinctive at a distance. During winter and into spring, the bill is bright orange (see the two righthand birds in the photo). Immatures sometimes have a reduced patch of orange (lower left bird with dark eye). The color is still orange, not yellow, and extends back under the nostrils. At other times of year and among juveniles on the breeding grounds, the bill is dark in both species.
Bill shape: This is helpful but takes practice and often remains subjective depending on angle. Barrow's is shorter and stubbier; Common longer and straighter (pointier). The stubbiness on Barrow's comes from the bill being shorter beyond the nostrils (or appearing that way) and having a subtle upcurve along the lower edge there to the tip. Barrow's also have a bill that narrows toward the tip when viewed directly down on a bird (rarely possible). Barrow's look like they have slightly curled or smiling lips, whereas Commons look more expressionless and flat.
Head shape: This too is fairly easy to discern even at a distance, but it is also one subject to postures and attitude, the head feathers being compressed or relaxed depending on the bird's activity and alertness. Under most conditions where birds are not diving actively or about to fly, Barrow's shows a steep forehead rising to a peak above or ahead of the eye, then a flat slope to the nape. A wedge-shaped mane usually projects backward at the base of the head. Common's head is more triangular and peaked, with the forehead sloping up from the bill to a peak above or behind the eye and the an angle to the back of the head that has a smaller mane (they do have a mane, and this confuses many observers). In profile from behind, Common shows a higher peak, but in the many birds I compared, this side to side profile is very similar.
Head color: This can be subtle supportive. As shown in the photo, Barrow's has a darker, chocolate brown head color. This is true even on immature birds. Commons are grayer-brown tending toward a yellow-brown spectrum, resulting in a brighter brown color.
Wing pattern: least helpful because goldeneyes fly with rapid wingbeats and usually have the important features hidden when on the water. The upper side of the forewing has less white on Barrow's age for age and sex for sex. Barrow's also has fewer white feathers in the secondaries (the big white patch one sees in flight). But counting this is hopeless. Adult female Common has a broad area of solid white in the forewing, and this difference can be seen well between the lefthand Common and the upper right Barrow's.
Ageing: The dark eye is a sign of immaturity, as is the pattern on the upper wing coverts, which just show on the immature (lower left) and adult (upper right) Barrow's. Adults tend to have more distinct white neck rings below the brown head and gray breast. If close and in good light, one can see that adults have blacker tertials and tertial coverts (feathers overlying the aft end of the wing). Again, the immature shows this difference for us, with its tertials being grayer (compare immature at lower left to adult at upper right).
The Odd One Out (the OOO, or oh-oh): The female that is 3rd from the left in the center struck me as odd over the entire time I studied it. The head shape consistently showed a steep forehead like a Barrow's, and the top of the crown is more rounded and uncharacteristic of Common. Moreover, the head color was quite dark brown. In the field, and to some extent in the photo, one can see that the color on the bill is brighter and more orange-yellow than flat, dull yellow typical of Common (even those that rarely can have all yellow bills). There's even a subtle upcurve to the ventral side of the tip beyond the nostrils. But overall, the bill looks long and pointy like a Common. The great amount of solid white visible in the forewing is a Common Goldeneye trait. It's certainly not intermediate, and this may suggest the bird is simply a Common and I'm reading too much into the subtle differences.
I've left this one unidentified, but some folks, including experts, have called this both Barrow's and Common. I'm quite sure it's not typical of Barrow's. This question is whether it is a pure Common Goldeneye. There are hybrid Barrow's x Common Goldeneye, and I have seen several males along this stretch of river. Male hybrids are favored to survive and tend to predominate in birds because of genetics (females are the heterogametic sex with ZW sex chromosomes), but one still expects and sees female hybrids. The problem with goldeneye is identifying a female hybrid. It's possible that this bird is a hybrid or had grandparents that hybridized, but it may just be a slightly odd Common Goldeneye. The fun thing about looking for hybrids is that it challenges our neat and clean IDs in the field, no more so than with subtly differing species.
Some helpful links:
immature female Barrow's wing
http://digitalcollections.pugetsound.edu/cdm/singleitem/collection/slaterwing/id/10404/rec/26
adult female Barrow's wing
http://digitalcollections.pugetsound.edu/cdm/singleitem/collection/slaterwing/id/10414/rec/36
immature female Common wing
http://digitalcollections.pugetsound.edu/cdm/singleitem/collection/slaterwing/id/10836/rec/7
adult female Common wing
http://digitalcollections.pugetsound.edu/cdm/singleitem/collection/slaterwing/id/10848/rec/19
ID of Common Goldeneye by wings
http://www.npwrc.usgs.gov/resource/birds/duckplum/comgldny.htm
ID of Barrow's Goldeneye by wings
http://www.npwrc.usgs.gov/resource/birds/duckplum/bargldny.htm
Louis Bevier
Fairfield, Maine
On Apr 22, 2014, at 9:23 AM, John Wyatt & Debbie Ryan <birdsnbeads@roadrunner.com> wrote:
> Starting at lower left, a BAGO, then clockwise from that bird; COGO,COGO,BAGO,BAGO. All female birds.
>
> I'm basing this primarily on bill shape and the extent and shape of the yellow pattern on the bill. The two upper-left birds appear to have longer bills than the others and have distinct yellow tips. The bills on the two birds at right look a bit stubbier with mostly yellow bills that kind of diffuses into the black - not a sharp break. The lower left bird might be younger since it appears to have a darker eye and the yellow on the bill has not extended as much on the bill as the birds at right. Its yellow does appear to be going up the bill on the top and side.
>
> I might be putting too much emphasis on the bills, as head shape could lead me to a different conclusion. The top bird has a very steep BAGO type forehead but I think the clean break to a yellow tip is quite rare in a BAGO and its bill looks long so I'll stick with a
> COGO. Similarly that lumpish look, stuck out at the rear of the head, on the left most bird makes me think BAGO but I'll stick with COGO on that as well due to the bill. I also think that head shape can be hard to judge with a single photo.
>
> Tough challenge Louis. Did I get any right?
>
> Good Birding,
> John
>
>
> On Apr 19, 2014, at 10:37 AM, Louis Bevier <lrbevier@colby.edu> wrote:
>
>> https://flic.kr/p/ncpq2d
>>
>> Don't duck the challenge of some subtleties. You can play this puzzle across and down. Have fun!
>>
>> Louis Bevier
>> Fairfield
>>
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