This morning as I went out to get the newspaper I startled a pair of juvenile Sharp Shinned Hawks in one of our large Aleppo Pine trees. It is breeding season, so I assume that one was a male and one was a female. (No way of knowing for sure). So, the first photo is one of the pair. The second photo is the other.
Here is a front view photo of the second, which helped me identify them:
Cooper's and Sharp Shinned Hawks have very similar plumage. While the Cooper's is five inches larger, size is not always easy as a distinguishing feature. Interestingly, the male of both species is smaller than the female. Therefore, a male Coopers may not be much larger than a female Sharp Shinned. I believe this to be a Sharp Shinned because the streaks on the breast are coarser and more rufous in color. The head seems a little smaller, no neck, and the bill seems shorter. Since distinguishing between the Sharp Shinned and the Coopers is difficult at best I always try to be sure I have identified them correctly. In preparing for the blog, I found a wonderful website from Cornell University (The Cornell Lab of Ornithology). I have copied their methodology for identifying one versus the other:
- 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.
- 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.
- 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.
- 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. As can be seen on the bottom of the Accipiter Photo Gallery page, 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.
- 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.
- 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.
- 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.
You can get more information from Cornell at their website:
http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/accipiterIDtable.htm
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