---------- Forwarded message ----------
From: Barbara Millikan <barbara.millikan@xxxxxxxxx>
Date: Mon, Mar 7, 2016 at 10:07 PM
Subject: Re: [obol] Re: A Different Kind of Bird Quiz
To: whoffman@xxxxxxxx
Some of what Wayne says could be attributed to a different angle and a
change of light on the feathers. Like the square posterior row vs the
rounded one could be just the difference in the way the bird is turned.
801, to use Wayne's ID, is pretty much broadside to the camera. In the 811
shot, the goose is rotated toward the camera maybe 10 to 20 degrees, and I
think the camera may be at a higher angle, looking slightly more down on
the goose.The rotation could easily account for why the white tail patch i
maller on 811 The goose's head is raised instead of dropped at rest on the
body like in 801. And the tail is up as well. This makes the body appear
shorter, and the raised head shortens the breast angle. The head shape,
cheek differences and bill shape *could* all be caused by the change in
camera angle. Or not. Also the light is different in the two shots, and
that could easily change the color of the feathers.
I carve things and I know how much one has to guess about the 3D shape from
the 2D picture.
The foreshortening in photo 811 accounts for a lot of Wayne's differences.
The more I think about this the more I think I'm looking at the same bird.
yrs
Barbara
On Mon, Mar 7, 2016 at 8:45 PM, <whoffman@xxxxxxxx> wrote:
Hi -
You have 3 photos with Canada Geese in poses suitable for comparison,
labeled ML25277341, ML25277801, and ML25277811. For simplicity I'll refer
to them by the last 3 digits, 341, 801, and 811. I am guessing you meant
us to compare 801 with 811 because 341 is included under the Snow Goose
heading, and also contains that bird. However, I will compare all three.
341 looks different to me. 341 shows a whiter chest, contrasting more
with the brownish flanks. The direction and lighting are different, but I
doubt that would fully account for the differences. The pattern of
"stacking" of the rows of upper wing coverts is also quite different. In
341 I see rows of coverts stacked neatly like rows of shingles. 801 and
811 show fewer rows, varying more in width, and give the appearance of
fewer feathers in each row, and more variation in feather size.
Now to compare 801 and 811: These are more similar, but I think they are
different birds as well. First, the appearance of the primary tips lying
against the tail is quite different. The tail is elevated in 811, which
could re-arrange the primaries, but I on't think that is the whole
explanation. There are also a bunch of differences in the wing coverts. I
recognize that with one vigorous shake, a goose could re-arrange these
feathers quite a bit, but the patterns seem too different to be accounted
for that way. Working from posterior forward, the posterior-most row looks
squared-off in outline on 801, and more rounded on 811. On 801 I see this
outer row, a second row, and then a row that appear to be smaller feathers
more tightly overlapped. On 811 the smaller, tightly overlapped row is the
4th one in. There are other detail differences in the coverts further
forward. A few feathers on each look darker than their surroundings, which
I suspect were more recently replaced. These seem to be in different
locations on the two birds. Moving forward, the white cheeks seem slightly
different in outline, with a slight posterior bulge on 801 that seems
absent on 811. The margin between the facial feathering and the bill seems
slightly different in the two, with the feathering extending slightly
farther forward on 811. The "points" on the bill seem to reach a bit
closer to the eye on 811. Finally, 801 appears to have a slightly more
prominent nail on the bill, and 811 appears to have a bump under the end of
the mandible.
Anyway, that's my stab at it.
Wayne
------------------------------
*From: *"Matthew G Hunter" <matthewghunter@xxxxxxxxx>
*To: *"obol" <obol@xxxxxxxxxxxxx>
*Sent: *Monday, March 7, 2016 7:02:05 PM
*Subject: *[obol] A Different Kind of Bird Quiz
If you go to this checklist and page down to the first two Canada Goose
photos:
http://ebird.org/ebird/view/checklist?subID=S27952911
Are these photos of the same bird? Are they photos of two different birds?
What differences can you see? Are they real differences, or due to bird
angle or position?
:-) What do you see?
Share your thoughts with the rest of us.
Matt Hunter
Melrose, OR
