Cooper’s Hawk – Accipiter cooperii – also known as Epervier de Cooper (French), Coopers Havik (Germany), Azor de Cooper (Spanish).
The Cooper’s Hawk and the Sharp-Shinned Hawk are pretty tough to distinguish. Both have gray and black barred tails (which distinguishes them from other hawks) and both have pretty similar breast and back patterns. In flight, the Cooper’s tail is more noticeably round, while the Sharp-Shinned’s is square, but that’s often tough to tell. I’ve found size the most helpful, as Cooper’s Hawks are generally crow-sized while Sharp-Shinned are generally blue jay-sized. Of course, juvenile Cooper’s can be the size of adult Sharp-Shinneds, etc. Generally, both have red eyes, too. But, when immature, their eyes are yellow.
Considering the above, the above is probably a juvenile Cooper’s Hawk. The gray and black barred tail tells me it’s one of the two (Cooper’s or Sharpie), and the yellow eyes tell me it’s a juvenile. His size, although hard to tell in the photo, appeared much bigger than a crow. Plus, he appeared to be following a skunk (I noticed the skunk running and started taking pictures and immediately this hawk landed in the tree above the skunk). A skunk would be too big for a smaller Sharp-Shinned. Incidentally, looking at what the hawk is chasing (or feeding on) can be an indicator. The smaller Sharpie will take sparrows and the like while the Cooper’s will often go after bigger doves, jays, and crows, as well as squirrels (and, apparently, skunks). In the second picture you can see the Cooper’s watching the skunk.
For a good discussion on distinguishing these two, check out this post at 10,000 birds.
And here’s a snapshot of the fleeing skunk as he headed for his hole. I believe he is a Striped Skunk.
Photo taken with the Canon Digital Rebel XT / 350D and a Sigma 70-300mm Lens on October 14, 2007 in Davenport, Iowa.