Cooper's Hawk
Accipiter cooperii
ID Notes 6
The Cooper's hawk, Accipiter cooperii, is a medium-sized hawk in the Accipiter genus. Accipiters are evolved for forest hunting, and tend to be characterized by long tails and short, rounded wings. They are smaller in size than other local hawks, such as the Red-tailed Hawk. The Cooper's Hawk is quite common in Western New York, and is often confused with our other common local Accipiter, the Sharp-shinned Hawk. Cooper's hawks are slightly larger than Sharp-shinned Hawks, but there is considerable overlap between small male Cooper's and large female Sharp-shins. Distinguishing between these hawks can be very challenging, even for experienced birders. I have listed a number of tips below that can help you if you are interested in working to improve your identification skills for these species. However, for our camera images, you cay also tag a bird as "hawk" if you cannot tell the difference.
Identification Tips (copied from Cornell's Project FeederWatch, https://feederwatch.org/learn/tricky-bird-ids/coopers-hawk-and-sharp-shinned-hawk/):
There are lots of field marks to distinguish these hawks, although some are judgment calls (such as size) and some require a certain perspective (front or back of bird). The best way to distinguish Sharp-shinned from Cooper’s hawks is to try to gather as many field marks as possible. Here are some key field marks to look for first:
1) With all plumages, Cooper’s Hawks are barrel shaped, with the width of the chest fairly close in size to the width of the hips and the largest portion of the chest about halfway down the body. Sharp-shinned Hawks, on the other hand, are widest at the shoulder and get distinctly narrower down to the hips.
2) The size of the head relative to the body can be a reliable field mark. It isn’t always easy to see, and hawks hold their heads in different positions that can affect how big the head looks, but usually a Sharp-shinned Hawk’s head looks small, and a Cooper’s Hawk’s head looks large. Sharp-shinned Hawks appear short-necked; Cooper’s Hawks appear tall.
3) Cooper’s Hawks are larger than Sharp-shinned Hawks, but size can be difficult to judge if you see the bird in isolation, and there is wide variability in size from one individual to the next and between larger females and smaller males in both species. Furthermore, large female Sharp-shinned Hawks can be nearly as large as small male Cooper’s Hawks. Generally, however, size can be a reliable field mark, especially if the bird is very large or very small.
4) Differences in leg size can be helpful for distinguishing between the hawks. Very thin legs are diagnostic for Sharp-shinned, and very thick legs are diagnostic for Cooper’s Hawk. This field mark requires some judgment, though, and sometimes it is hard to tell if the legs are thick or thin.
5) The rounded versus square tail is reliable if you can see all the tail feathers and they are held straight. The tail feathers of Sharp-shinned Hawks are the same length, whereas the outer tail feathers are shorter than the inner feathers on Cooper’s Hawks. However, when seen from the back, if a Cooper’s Hawk holds its tail tightly closed, the longer feathers can completely block the shorter feathers from view, making the tail look square. Furthermore, a Sharp-shinned Hawk’s tail can look rounded if the feathers are spread. New feathers growing in can further complicate the issue.
6) Determine if the hawk is an adult or a juvenile. Adult Sharp-shinned Hawks and Cooper’s Hawks have dark gray backs, rusty-barring on the breast, and red eyes. Juvenile Sharp-shinned and Cooper’s hawks have yellow eyes, dark vertical stripes on their breasts, and variable brown backs and heads with some white spots.
7) If you can see the front of the hawk and it is a juvenile hawk, the thickness and color of vertical streaks is fairly reliable. There is some overlap between the species, but this is pretty unusual. Very thick, rufous stripes that extend down the lower belly are a good indication of Sharp-shinned Hawk, and very thin, dark streaks that fade away on the lower belly are a good indication of Cooper’s Hawk.
If you can see the back of the hawk, and it is an adult, then the color of the nape is a reliable field mark. Cooper’s Hawks have a pale nape with a clear contrast to a dark cap. Juveniles of both species can show a pale nape, however.
8) In flight, the birds can be especially challenging, but there are a couple of tips that could help. When soaring, the Sharp-shinned Hawk has short rounded wings are pushed forward at the wrists so that the small head barely extends past the wings. The large, angular head of the Cooper’s Hawk, on the other hand, projects far beyond the wings when soaring, giving the bird a cross-like appearance. The Sharp-shinned Hawk typically flies with several quick wingbeats followed by a short glide. The wing beats can be erratic and more difficult to count than for a Cooper’s, which often flies with slower wing beats followed by a short glide. The slower, regular wing beats are easily counted when a Cooper’s Hawk flies overhead.
Fontes e Créditos
- (c) Jim Johnson, alguns direitos reservados (CC BY-NC-ND), uploaded by Jim Johnson
- (c) Mdf, alguns direitos reservados (CC BY-SA), http://commons.wikimedia.org/wiki/File:Accipiter-cooperii-01.jpg
- (c) SearchNetMedia, alguns direitos reservados (CC BY), http://commons.wikimedia.org/wiki/File:Accipiter_cooperii_1.jpg
- John James Audubon , sem restrições de direitos de autor conhecidas (domínio público), http://commons.wikimedia.org/wiki/File:Accipiter_cooperii_audubon.jpg
- (c) Mykola Swarnyk, alguns direitos reservados (CC BY-SA), http://commons.wikimedia.org/wiki/File:Accipiter_cooperii_m_Sam_Smith_Toronto1.jpg
- Adaptado por Robin Foster de uma obra de (c) Wikipedia, alguns direitos reservados (CC BY-SA), https://en.wikipedia.org/wiki/Accipiter_cooperii
