"Answer" Revised 2/24/00
Dark phase raptors present among the most difficult of identification
problems. Many a good birder has his/her heart sink when a dark
phase raptor comes into view since many of the traditional field
marks are not visible. However, let's plug ahead anyway.
Our bird is mostly uniformly brown with a pale mark leading from the rear of the eye to the end of the auricular region and another bit of pale on the forehead directly above the bill. There appears to be some additional pale feathering near the edge of the visible wing and there is a very faint bit of feathering directly in the center of the breast. The bird is fairly plump, presumably indicative of the genus buteo. However, the most important field mark is the one not often used in the field, but very useful in photographs; the legs are feathered all the way down to the toes. While not quite diagnostic, the choices are rapidly narrowed to FERRUGINOUS HAWK and ROUGH-LEGGED HAWK.
For the moment, let's consider only adult birds of either species. Adult FEHA should show an undertail which is white even in a dark morph bird, which doesn't appear good for this bird (though little detail of the undertail is visible in the scan). However, adult dark-morph FEHA as dark as our bird should show an entirely dark forehead with no pale areas, which also doesn't look good for our bird. By contrast, dark-morph RLHA should show some paleness on the forehead as well as possibly some other paleness behind the eye, which is good for our bird. Male RLHA is jet black, which is not good for our bird, but female RLHA is dark brown, certainly consistent with this bird. The undertail of a female dark-morph RLHA is dominatly dark, with a broad, silvery subterminal band. This is not visible here and I'm not quite sure why, unless it's an artifact of the scan or it's not visible due to loose feathering on the undertail coverts. If you have a better explanation, please let me know. Bill size relative to head size may also be useful; RLHA tends to look small-billed while FEHA tends to look longer. How reliable this is, I don't know.
Immature birds of either species complicate the matter. Juvenile dark-morph FEHA can also be dark brown heads and backs, but head and breast are lighter colored and contrast with the rest of the upper parts and belly which appears to be at odds for this bird. Dark-morph juvenile RLHA is similar to female dark-morph RLHA other than the dusky band at the tip of the poorly rendered tail. However, even juvenile RLHA should show paleness on the forehead similar to adult female RLHA.
With the lack of detail in this photograph, separating adult female from juvenile RLHA appears not to be possible. This dark-morph female/juvenile ROUGH-LEGGED HAWK was photographed on the Samish Flats, WA in February of 1999.
Last updated 24 February, 2000