September and October is going to be crazy when it comes to Red-tails and I want to make sure that anyone following the project understands what they may be seeing, since I've misidentified several in the past. So migration season has some crazy-looking Red-tails that may very well baffled an observer who's trying to make a subspecies/morph id. So here's a brief overview of what to look for.
Western Red-tailed Hawk (Buteo jamaicensis calurus)
The Western Red-tailed is the most variable subspecies in the entire species and here's why. One, they are only subspecies with dark morphs besides the distinct Harlan's and probably Northern Red-tails. And to add on to it, it appears they have geographical variance to the subspecies too. So here's what you're looking for:
Light morphs: Any individuals that are light-colored and show a distinct bellyband.
https://macaulaylibrary.org/asset/163347291#_ga=2.258507466.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/59538521#_ga=2.202534481.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/67813041#_ga=2.202534481.1183214068.1566829911-1175263981.1555651889
Rufous Wash: Light morph individuals that have a rich rufous 'wash' to the breast. Intermediate between light and rufous morphs.
https://macaulaylibrary.org/asset/119750351#_ga=2.262849996.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/116865651#_ga=2.254509640.1183214068.1566829911-1175263981.1555651889
Rufous morph: Where the breast is rufous and the bellyband is indistinct but there.
https://macaulaylibrary.org/asset/169150031#_ga=2.265929039.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/114077951#_ga=2.27814524.1183214068.1566829911-1175263981.1555651889
Dark morph: Sometimes will be lumped with rufous morph (especially if individual is in flight) but appear darker and browner than rufous.
https://macaulaylibrary.org/asset/141548421
https://macaulaylibrary.org/asset/97549721#_ga=2.22635003.1183214068.1566829911-1175263981.1555651889
Juvenile Light Morph: Most of what you're going to see as in the examples below.
https://macaulaylibrary.org/asset/132098401#_ga=2.190497259.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/52755331#_ga=2.198807151.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/41766191#_ga=2.227641693.1183214068.1566829911-1175263981.1555651889
Juvenile Intermediate/Dark Morph: Much less common than light juvies that usually have more markings.
https://macaulaylibrary.org/asset/136010161#_ga=2.224964058.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/132106671#_ga=2.224964058.1183214068.1566829911-1175263981.1555651889
Eastern Red-tailed Hawk (B. j. borealis)
The most common subspecies in Eastern US, they still nest on the Alberta Rocky Mountain front and often they migrate through a pass in the mountains and end up where? That's right in inland WA and OR. The best ways to distinguish an Eastern from a Western (and trust me, it's the hardest id to make) is from well mottled upperparts, white throat, white supercilium, thin patagial marks, a thin bellyband that usually lacks barring and nearly no rufous/buff washing to the underparts and underwing coverts. But remember that these traits are not definitive, these are just what they might look like. The first photo is an Eastern Red-tailed in Washington and the second is a probably intergrade but the picture shows traits of Eastern.
https://macaulaylibrary.org/asset/42988881
https://macaulaylibrary.org/asset/119765151#_ga=2.235916865.1183214068.1566829911-1175263981.1555651889
Northern Red-tailed Hawk (B. j. albietcola)
A recently described subspecies that breeds in Canada and winters in the US, generally east of the Rockies. But once again, since they nest in Yukon and Alberta, it's not unheard of that they flew through a mountain pass in the Rockies into WA or OR. There are apparently dark morphs but they are not very documented, so I'm not sure if we can safely identify one. They differ from Western Red-tails by having a thick black, not brown, bellyband that is typically arrow-shaped streaking. They also have a significant amount on streaking on the sides of the breast. You might have a Northern Red-tailed or if you something like these Western Red-tailed.
https://macaulaylibrary.org/asset/125017711#_ga=2.265513295.1183214068.1566829911-1175263981.1555651889
https://macaulaylibrary.org/asset/77321111
The one thing I can't do is juveniles since the other subspecies are so similar to Western juvies, it's next to impossible to identify. I will not go into Harlan's because they are relatively easy to identify and if you have one, I'll make sure to let you know. Good luck out there iNaturalists and wish you the best luck in finding unusual Red-tails.