Western Red-tailed Hawks show a continuum of plumages from whitish and lightly marked on the underbody to completely dark. I can't possibly show all the variation from light to dark in a blog post or even in a full-length article, so I just wanted to discuss "darker" adults. Many Western light-morphs (top left) are rufous-toned underneath with typically marked patagials and bellies, but some are rufous-toned with minimal bellybands (top center). A few are strongly rufous-toned with typical bellybands (4th bird on top by Vic Berardi).
Note the rest of the birds shown have varying bellybands and apparent patagials until you see the 2 birds on the bottom right, which are typical dark-morphs. One being rufous-chested, the other solid dark. The term rufous-morph, or "intermediate-morph", is used to describe birds that are dark underneath with slightly paler rufous chests, but these birds are often difficult to tell from solid dark birds in the field. However, would you qualify some of the other birds in this collage as rufous-morphs? I wouldn't argue.
Where do you draw the line? I tend to call birds that are nearly completely dark underneath with solid bellybands and masked patagials "dark-morphs", and birds with streaked bellies "rufousy light-morphs", or "rufous-toned light-morphs"...if you take the term "rufous-morph" out of the equation. Confused? Regardless, there are just a bunch of birds out there that can't truly be categorized to morph.....or race in certain cases (that is for the next blog entry, and more interesting to me). Anyway, I don't get too caught up in trying to pin a label on every Red-tail, it can drive you crazy...or crazier in my case.
Labels: identification, plumage, raptors