I agree with Roger on the field marks. I also use tarsus size (when the legs are visible), and also that some juvenile Goshawks have a hint of a facial disk.
Keep in mind that there's a lot of individual variation, as if these guys aren't tricky enough already. :-). Some Cooper's Hawks are as heavily marked as Goshawks, and some have streaked undertail coverts, which is generally considered a Gos field mark.
I'm not crazy about Brian Wheeler's book, for several reasons, but some of his photos of these two species are useful for comparisons.

Ruth Taylor
Seattle/Ballard
rutht at seanet.com
-----Original Message-----
From: Rolan Nelson <rnbuffle at yahoo.com>
To: tweeters at u.washington.edu <tweeters at u.washington.edu>
Date: Friday, October 13, 2006 11:12 PM
Subject: [Tweeters] Recent Accipiter ID Question


Tweets,

I received the following from Roger Orness with his consent to pass it along to Tweeters. I stand corrected, and I'm reminded just how useful this list can be!

-Rolan

I'm not an official Tweeter's subscriber, but I will add my too sense.
This is a Cooper's Hawk. The graduated lengths of the tail feathers
and the beak size and profile are the keys. Compare with the below:

http://www.peregrine-foundation.ca/raptors/Goshawk.html

The GOSH GURU and my mentor Bud is out of town and I'm pretty
sure he'd vote the same, but I'll forward this to him for the final say.

Roger Orness


Rolan Nelson
Fircrest, WA
rnbuffle at yahoo.com


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