Daryll Myhr shared these adult Red-tailed Hawk photos with me from British Columbia (thank you Daryll). He has shared lots of photos with me over the past few years, and it is always great to see what he has for me in my inbox. This is one of those birds that gets people wondering if it is a Krider's or Harlan's, and for good reason. Some light-morph Harlan's look similar to Krider's and some of the plumage traits overlap at times…and hey, they should, they are both Red-tailed Hawks. However, there are definite ways to distinguish faintly marked, pale-headed Harlan's from Krider's. We summarize this pretty well in 2 articles in a 2009 issue of Birding magazine if anyone wants to download it here:
Anyway, check out the dark, cold brown upperside and head, white streaks on head and over the eye, pale mottling limited to the scapulars, brownish mottling on the tail, distinct / blobby belly streaks, and snow-white body plumage. These are all Harlan's traits. This just happens to be a Harlan's with a white-based tail ( a common tail type on light adults), which is what causes most of the confusion. Although it's fairly out of range for Krider's, I don't ID birds based on range or probability, just on sound ID criteria such as plumage and structure. To clarify -- adult Krider's have buffy underbodies, thin belly streaks, warm brown uppersides, (often) extensive, pale mottling on the upperwing coverts, and uniform whitish heads (often lack white streaking), or golden brown heads (not dark, "cold" brown. The tail of adult Krider's is often whitish with a pinkish tip, but not mottled with gray or brown like this bird. There are other differences as well, but the birds wings are not spread in these photos, so I won't mention them…they are mentioned in the articles though.
I hope this helps people separate these two similar subspecies, and feel free to comment or ask questions, hopefully I can answer them.