[CT Birds] Accipiter ID Update

Anthony Zemba Anthony.Zemba at gza.com
Wed Feb 1 10:50:19 EST 2012


I enjoyed following this debate as I had a similar experience down at Silver Sands in late December 2011.  Still needing a Goshawk for the year, I was surprised and excited when a large imm. accipter alighted on a fallen branch near the creek by the entrance road. When I looked through the binoculars I found said bird to have a defined/distinct white supercillium that one would expect to see in Goshawk. If I remember correctly, Sibley does not depict a broad white supercillium for Cooper's but does so for Goshawk.  But I was unconvinced it was a Goshawk, which was disappointing since I needed one for the year still.  The Silver Sands bird had too fine a streaking on an otherwise too clear white breast, seemed too sleek, and had no tawnniess on the wing. I could not see the tail because it was blocked by vegetation. When I looked in the Crossley Guide upon return home, I noticed Crossley had photograph(s) of am immature coop sporting a white supercillium, and I was convinced that that was what I had that day at Silver Sands.

Anthony Zemba CHMM
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GZA GeoEnvironmental, Inc.

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-----Original Message-----
From: ctbirds-bounces at lists.ctbirding.org [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of greg hanisek
Sent: Tuesday, January 31, 2012 9:10 PM
To: Joseph Cala
Cc: ctbirds at lists.ctbirding.org
Subject: Re: [CT Birds] Accipiter ID Update

As Joe notes, it is amazing how people can look at the same images and see the same features in different ways. Here is my take, which I'd written but hadn't sent yet just before Joe's follow-up post:

Identification of difficult subjects such as immature Accipiters from photos is fraught with the opportunity to go down the wrong path. Doing it from one photo can easily result in an incorrect result. Having 2 photos in this case allows for at least a bit more confidence.

My first impression, especially from the profile shot, is of a bird that lacks the mass and power of a N. Goshawk. Of course, with nothing for direct comparison this is just an impression. Looking at some more specific marks, I still believe this is a Cooper’s Hawk. It seems like the photo is a bit over exposed, which may be creating an unnaturally stark, contrasty look to the plumage. That said the bird seems to lack the tawny background color to the underparts that would be typical of an imm. goshawk. It also lacks some buff on the wing coverts and a brown auricular patch, which are goshawk marks. The exposure may be giving a false impression of eye color, but the bird in the picture does not show the richer orangish-yellow iris of an imm. goshawk. The very fine markings on the leg feathering work better for a Cooper’s, and the tail pattern doesn’t seem to fit goshawk. The dark bars on a goshawk’s tail are offset from feather to feather,  creating a zig-zag look. The angle on the photo isn’t great for seeing this, but dark bars seem to run straight across. The bars also seem to lack the thin white borders possessed by a goshawk.

The classic N Goshawk field mark in the white supercillium, but this leads to a lot of misidentifications if it’s the only mark used. A number of hawks, notably imm Cooper’s and Red-shoulders, can show supercilliums to varying degrees, leading to misidentification as goshawks. The bird in the photos appears to have a short supercillium, which is typical for an immature Cooper’s Hawk.

Greg Hanisek


--- On Tue, 1/31/12, Joseph Cala <Joejr14 at aol.com> wrote:


From: Joseph Cala <Joejr14 at aol.com>
Subject: [CT Birds] Accipiter ID Update
To: ctbirds at lists.ctbirding.org
Date: Tuesday, January 31, 2012, 4:37 PM


So the tally from the responses has been four votes for Goshawk, two for Coopers.

Most of the responses received back from the Ohio Listserv have apparently been for Cooper's.

Here's a basic rundown of the specific field marks referenced as to why Coop v Gos.

Cooper's:
Breast streaking is too fine
Tail bands are not bordered with light line Tail bands are straight across--not wavy Too little gray space between tail bands Range (Apparently Goshawks in Ohio are very rare, even during migration.  An Ohio poster on the forum claims that they just had their first photographed Goshawk confirmation in Ohio last year) Lightly marked white supercilium Pale yellow iris color No brown patch in the auricular area

Goshawk:
Size
White supercilium plenty bold enough for Gos.
Some tail bands have thin white edging, some don't.
Dark cheek bands with white in between, plus streaking on the throat White bars in greater coverts White bars within light tail bands Uneven tail bands White tips to the tail feathers instead of white banding as in Coops


A quote from a prominent Ohio birder:
"On this bird, the streaking is entirely too fine and widespread for Gos, the face too punched in and "surprised" (Gos is buteo-like and more fierce), and the underparts streaking too fine and scattered. Overall, while size is difficult to judge without comparison(s), the bird is too sleek and well-proportioned. Goshawk is a large, bulky bird, more like a buteo. Goshawks are heavy, built, more reminiscent of Red-shouldered immature, or small immature Red-tailed in overall girth and proportion.

In this case, while this bird appears to have a clear and defined white supercilium, the full span of ID marks does not add up to Gos. Many Cooper's can show clear eye-lines but all marks must add up."

I find it very interesting that a good number of people can look at the same picture and reference the same exact field marks and come up with two completely different conclusions.  I absolutely love debate like this.  One thing I do wonder, if Goshawks are indeed such a rare bird in Ohio, is that factoring into why so many birders from Ohio are calling this a Cooper's?

Anybody have any additional thoughts?







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