Some adult Northern (abieticola) Red-tailed Hawks can be quite orangish to the underside. In some examples, the combination of extensive orangish tones to the underparts & extensive chest streaking lends a particular bird a non-light morph appearance. As far as raptor experts and enthusiasts know, polymorphism does not exist in the borealis and/or “abieticola” subspecies, with only light birds known to exist in breeding populations. Some of these light birds are far from light in the traditional sense, however, and I showcase some photos of very orangish-reddish birds below. Polymorphism keeps prey on its toes in open and variable habitat. Western (calurus) Red-tailed Hawks have long received this selective pressure, hence the variability in plumage variety (light, intermediate, dark). In the boreal forest throughout the northeast, the selective pressure for a polymorphic gene pool is evidently quite low; the homogeneity of the rather dense habitat is likely the reason for this.
Acknowledgements: Thank you to Nigel Shaw and Brett Fried of Simcoe County Banding Group (https://www.facebook.com/simcoecountybanding/?fref=ts) for allowing use of these superb photos.