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Accipiter ID
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Paul M. Roberts
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Dec 06, 2005 22:22 PST
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Ann's pictures are great. Were they through a window, Ann? If so, they
are even more incredible. Whatever, they are gorgeous, of a gorgeous bird.
Responding to John Sharp's post, my impression of the bird is adult
Sharp-shinned Hawk.
Clearly an accipiter. Long, narrow tail, and short wings when folded and
perched. Blueish/gray back, red-barred breast, and red eye say adult
Sharpie or Cooper's. The bluish-gray appearance and chunky breast say
female. However, in photos 1 & 6, the two-toned appearance of the upper
wing, with the arm looking bluish and the hand looking darker (browner),
suggests male. Adult. Gender questionable. Size would be helpful here,
but it is difficult to accurately judge size from still photos.
Now Cooper's or Sharpie?
Photo 1 shows a small, rounded head. Sharpie. Cooper's have a larger
head in proportion to their body and it often looks squarish, or boxy,
because they frequently have their hackles raised, which you don't see
on Sharpies.
Photo 2 shows smaller head and relatively thin legs. Sharpies have "pipe
cleaner" to pencil legs. Cooper's have legs thicker than a pencil.
Photo 3 shows a continuous tone from the crown, down the nape and back.
Only adult Sharpies have this. Cooper's have a lighter nape, contrasting
with a dark cap and a dark back. You also see a
straight tail tip (Sharpie), not the rounded tail of a Cooper's ( which
can look straighter when perched than in flight). You also see a very
narrow dirty white terminal tail band. That is typical of Sharpies,
particularly females. Brian Wheeler says male sharpies are more likely
to have a thicker, whiter terminal tail band, more similar to a
Cooper's, which has a thick white terminal tail band. Terminal white
bands are move obvious in the fall, and fray over the course of a winter
and spring, when they become a less reliable field mark.
Photo 4 reinforces comments above on the back and tail. Note the rufous
cheek, which when seen at an angle can look like a light nape, hence
more like a Cooper's. The excellent photos from the rear (3&8) show you
that this is not the case, however.
Photo 5 is perhaps the weakest, but you see the small head, the reddish
breast, the dark eye, the long tail and short wings. Notice here the
reddish cheeks, or auriculars, now look like a light nape, or Cooper's.
Photos can lie.
The remaining photos reinforce field marks discussed above. Thus, adult
Sharpie, gender questionable. There is no need for people to attempt to
identify the gender of all individual raptors. If the bird is really
huge for its species, it's a female. If it is really small, a male. In
between it is very easy to be wrong, and best judged by measuring birds
in hand unless there are distinct plumage differences, as in the kestrel.
Also note that beauty - and other judgments - is in the eyes of the
beholder. John Sharp is a pretty astute observer. He thought the tail
looked rounded, and that there looked to be a light nape. I think John
probably focused on the majority of the photos where the rufous cheeks
made a strong impression of a light nape, whereas the continuous tone of
the crown, nape and back is obvious only on photos 3 and 8.
It is harder to accurately judge a folded tail than a fanned one as to
shape, but to my eyes, in photos 3 & 8 the central tail feathers
(rectrices) look no longer, actually a little bit shorter, than the
outer tail feathers. John had a different impression of the tail, again
perhaps from focusing on different photos. If photos 3& 8 had not been
taken, documenting accurate identification would be considerably more
uncertain.
Some might recall the accipiter identification challenge of last year,
when I asked two accipiter experts from out of state, who have each
handled thousands of sharpies and hundreds if not thousands of Cooper's,
to identify the species of I think six different accipiters whose photos
had been posed on Arlington Birds. My recollection is that the three of
us agreed on only one or two of the birds. Accipiter identification can
be difficult.
One final note. Julie was driving along Mystic Avenue in east Medford
late today and saw a large hawk fly across the road into a tree. She did
not get a good look, but her immediate impression was Goshawk....
Paul M. Roberts
Medford, Ma
pha-@world.std.com
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