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
