Hello all,


Bill, thanks for sending me the additional photos- an excellent series.


In all of the Tweeters posts concerning differential identification of Cooper's and Sharp-shinned hawks, there is almost always something missing that would help increase the probability of correctly identify the species. For good reason- if we are lucky, we get to see one of these great birds briefly-- the Cooper's is one of my favorite species-- and usually get to take a single or very few shots- often in less than favorable conditions.


In this case, we cannot see the dorsal surfaces, including tail, which would give us a better sense of body proportions and the shape of the tail tip which usually appears more rounded, and at this time of the year, has a wider White terminal tail band than the Sharp-shinned. Also, we cannot see the shading and coloration of the head including nape.


In an ideal and very unlikely situation, we would have most or all of the following photos and observations of an Accipiter in question:


1. Bird in a size context that we all understand- for example a Female Cooper's and Sharp-shinned hawk, side by side. Or more likely, next to an object that we are familiar with in term of dimensions.
2. Great lighting with fine exposure.
3. Three full frame shots of all Dorsal surfaces of the hawk, including tail.
4. Three close-up and side views of the head,
5. Three full frame photos of all ventral views of the bird.
6. Three fine photo captures of the dorsal surfaces of the tail feathers at rest and spread.
7. One or more stereotypical behaviors for the species
8. Flight characteristics, including observations on wingbeat pattern and and body and wing shape/orientation when soaring or gliding- I usually miss these-the sightings are usually brief and surprising.
9. One good shot of leg dimensions-see Bill's photos.
10. Voice. The voice of an adult Cooper's is very distinctive.


Of course this does not happen, so the more information the greater the probabilities.

Each time someone on Tweeters poses the question regarding Accipiter identification, I learn something.


In this case: I reviewed several sources and found: Cooper's "Often perches on telephone poles, unlike Sharp-shinned" (National Geo. Illustrated Birds of North America).


And: "Cooper's often perches on fence posts or poles, as well as tree branches, while Sharp-shinned almost always perches on tree branches" (Sibley's Guide to Birds).


I am certainly no expertl, but ways enjoy these exercises involving these two species.


Best regards,
Dan Reiff
Mercer Island





----- Original Message -----
From: notcalm at comcast.net
To: "Bill Anderson" <billandersonbic at yahoo.com>, "Jack Stephens" <jstephens62 at comcast.net>
Cc: "Tweeters" <tweeters at u.washington.edu>
Sent: Wednesday, November 13, 2013 10:32:19 PM
Subject: Re: [Tweeters] Edmonds accipiter




Bill,


I would agree with Jack for all the reasons he listed. The first photo is very distant, but appears to show a flat topped head, not the rounded, ping pong ball like oval of a Sharp-shinned hawk. Also the leg thickness, well shown in the second photo is appears robust and the thickness expected in a Coopers. The Sharp-shinned's legs would be noticeably thinner.


Do you have another, different photo and angle like second photo showing the head profile? This would help make for the ID.


But-- I defer to the experts.

----- Original Message -----
From: "Jack Stephens" <jstephens62 at comcast.net>
To: "Tweeters" <tweeters at u.washington.edu>
Sent: Wednesday, November 13, 2013 6:53:04 PM
Subject: [Tweeters] Edmonds accipiter

Earlier today Bill Anderson wrote:

"Scroll down to the bottom of page 50 for photos and further narrative. I will appreciate feedback as to whether the Accipiter I photographed was a sharp-shinned hawk or a Cooper's hawk.

http://www.pnwphotos.com/forum/showthread.php?7934-Wildlife-of-Edmonds-WA/page50"


I would vote for Cooper's Hawk. The head seems blocky, with a capped
appearance. The eye seems a bit small and much closer to the bill than
to the back of the head. The pole the bird is on gives some idea of
size, and it seems relatively large for an accipiter. You can't see the
tail or the nape, which would help, but for me everything lines up for
adult Cooper's Hawk.

Jack Stephens
Edmonds, WA
jstephens62 at comcast.net
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