Much larger than his cousin, the Sharp-shinned.

"Immature Cooper's and sharp-shinned hawks are never tougher to
identify than when they are just sitting there letting you look at them.

The best field mark is size - A big bird is a femail COop, a small one is a male sharpie.

A second field mark, the streaking on the breast and underparts, is worth a close look.
On most Cooper's hawks, the streaking on the breast is fairly fine and dark brown and desn't
extend very far onto the belly. On most sharp-shinneds the streaking is heavier, broader, with
teardrop-shaped spots, and extends farther onto the belly; sometimes there is a reddish tinge to
the streaking.

The thrid best field mark is the length and shape of the tail. Especially long-talked birds are
almost surely COops. It is hard to guage the shorter tail of shapries, but on sitting birds the
tail shampe is a more useflu character than it is on flying birds. Sharpies of all ages and sexes
almost alwasy show a notched tail whtn they are sitting. Sitting Cooper's hawks rareley show a
notch in th tail."