Cooper’s or Sharp-shinned?

As I noted in yesterday’s post about the sharp-shinned hawk (Accipiter striatus), it is tricky to distinguish a sharpie from a Cooper’s hawk (Accipiter cooperi) in the field. They look so much alike!

Size, head shape and subtle coloration are not enough to make, at least for me, a difinitive identification. Oh yes, I forgot to mention that the legs of a sharp-shinned hawk are “skinnier” than those of a Cooper’s hawk. “Excuse me, will you please fly over there next to that Cooper’s hawk so I can compare your leg diameters?” Right!

There is one feature that I usually do find useful in separating the two species – the tails. Although both the sharp-shinned and Cooper’s hawks have long tails with broad banding, the sharp-shinned hawk’s tail feathers are all the same length and present a squared off appearance. In contrast, the outer tail feathers of a Cooper’s hawk are shorter than the inner feathers. This makes the Cooper’s hawk tail look rounded or fan shaped. In flight the sharp-shinned tail looks square and the Cooper’s hawk tail is more rounded. That one characteristic is the most valuable to me.

This difference can be seen in the pictures of the two hawks taken from behind. Both the Cooper’s and sharpie were sitting in the cottonwoods by our house (Lookout CA)¬†patiently waiting to ambush an unsuspecting songbird.

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