Cooper's hawk.
One field mark I look for (and have mentioned before) is the location of the birds eyes on it's head. Sharp-shinned's eyes are very close to the front of the face, and Cooper's are farther back.
Also, the amount of white on the lower belly is more extensive than in Sharpies... which is shown in this photo.
(And the legs are too thick) =)
Life List: 302
Recent Lifers:
November:
Vesper Sparrow
Black Scotor
Surf Scotor
October:
Hudsonian Godwit