Sharp-shinned, left. Here are some generally accepted id pointers: 1 - Flight behavior. While flying high and in the open, the Sharp-shinned alternates flapping followed by a "drifty" glide. The wing beats are quick and flicking. The Cooper's wing beats are strong and stiff. 2 - Body shape. The Cooper's head and neck jut well forward of the wings. The Sharp-shinned's head and neck appear to be "pulled in" and its wrist joints are more obvious that those of the Cooper, and seem to be pressed more forward in the bird's soar. 3- Tail shape. The Sharpie's tail is more squared-off than the Cooper's, and the terminal band is more gray than white. The Cooper's tail, conversely, is a bit rounder and the white terminal band is more distinct. (This is most noticeable in the fall and can be worn off by spring) Male Sharp-shinned Hawks average 57% of the body mass of females, the most sexually dimorphic of all North American raptors. The Coopers Hawk derives its name from William C. Cooper, a New York scientist and father of James C. Cooper, for whom the Cooper Ornithological Society is named.