The Cape May Bird Observatory has an outstanding blog, with great pics and info. That info includes 16 ways to tell a Sharp-shinned Hawk from a Cooper's Hawk,
This info was featured in a post earlier this month. To read it, click here.
To see the blog itself, View From the Cape, click here.
(A big thank you to Don Freiday of CMBO for the information, and a thank you, too, to Edna Duffy and Julie McCall for passing along the link.)