I have looked at the 2 photos that Ben Weinstein took of the accipiter (
back yard nesters).
The 2nd photo, which shows the bird flying, is the most diagnostic in my
opinion. The head is large
and projects out well past the leading edge of the wings. In other words,
the head is really ahead of the wings,
whereas with a Sharpie the head does not extend past the leading edge to
such an extent. 
One way of thinking about this: if the bird wanted to look left or right
while flying, with a Cooper's Hawk, the bird could turn the head without
having to move the rest of its body, but with a Sharpie moving the head to
the right or left
would cause it to move its wings, shoulders etc.

The flying photo points to a Cooper's hawk.

Also, the first photo ( sitting accipiter ) has some supporting marks for
Cooper's: rounded tail and dark cap.
Best mark is the large head in flight relative to the leading edge of the
wings. 

What do other's think? I'd like to hear from other's on Osprey with a lot of
experience looking at accipiters.
Accipiter ID is always a good area to get into. Remember in the 1970's some
experts were saying you cannot tell the 2
species apart in the field. Has that changed totally now?



   Good birding!   

   Taylor McLean
   410-377-2153
   
   Baltimore County
   Towson, MD