The Cooper's hawk is a common sight around Illinois, and it's a very interesting little bird. The Cooper's Hawk is from the genus Accipiter, which contains a large group of small hawks, including the Northern goshawk and the sharp-shinned hawk, other hawks native to Illinois. The Cooper's hawk is particularly interesting for a number of reasons, one of which is its hunting style.
Cooper's hawks hunt mainly in the cover of trees and shrubbery, and rely on surprise to catch their prey. Northern goshawks and sharp-shinned hawks do this, too, but the Cooper's hawk is particularly enthusiastic. When it lunges forward to strike prey, it is definitely not cautious. The Cooper's hawk is well known for absolutely crashing through the brush toward its prey, to the point of nearly injuring itself. When Cooper's hawks are examined and tagged by scientists, the scientists often see healed fractures in the bones of the hawks, indicating that they often injure themselves when they hunt. If nothing else, the Cooper's hawk is certainly enthusiastic.
The Cooper's hawk also looks different from the other hawk that is common in Illinois, the red-tailed hawk. Cooper's hawks have dark gray plumage on the tops of their bodies that almost looks blue, and on their underside, they have beige and dark brown striped plumage. Their tails are striped light gray and dark gray, a notable difference from the red-tailed hawk's signature tail. Cooper's hawks are also smaller than red-tailed hawks, and are relatively small as hawks go.
They are known for landing in people's back yards to catch prey, so if you see a gray hawk perching on your fence, it's probably a Cooper's hawk. Cooper's hawks are also pretty noisy, and rely on many different vocalizations to communicate with their mates. Generally, the male's voice is of a higher pitch than the female's, and they often call to each other during the breeding season, especially before they have chicks. As with most animals, Cooper's hawks breed in spring, but you can keep watch for them no matter the season. Hopefully as the leaves fall, they'll be easier to see. Keep your eyes open for this very interesting hawk!