Red-tailed Hawks (Buteo jamaicensis) are ubiquitous in North America, and are probably the most abundant and familiar raptor. They’re also very diverse with over a half-dozen subspecies, a few of which are strikingly polymorphic showing a continuum of color morphs ranging from almost solid black down to very pale. Not to mention solid white individuals that pop up from time to time. But when different Red-tailed Hawk subspecies show up as vagrants on the wrong side of the continent, how often do we noticing them?
In the west, both Harlan’s (B. j. harlanii) and Western Red-tails (B. j. calurs) come in a whole range of colors, from light to nearly black, and these are typically categorized as either light, light intermediate, intermediate, dark intermediate, or dark, with very few birds being solidly dark enough to qualify for the latter category. Westerns tend to show lots of rusty/rufous tones in contrast to the colder colors of most Harlan’s, so when talking about Westerns many often relabel the above categories using “rufous” instead of “intermediate.” It’s all rather unfortunate terminology, really, as most non-experts are prone to call any bird darker than a typical light morph a “dark” Red-tailed hawk.
In the eastern part of the continent, the Eastern Red-tailed Hawk (B. j. borealis) dominates, and is in fact the only subspecies you’ll likely encounter save the Northern Red-tail (B. j. abieticolis) which may just be variation within borealis and not be a legit subspecies, but is distinctive in that it appears to be a bit more richly colored, and more heavily streaked, than other borealis (sensu lato). That said, there is currently zero evidence that these eastern subspecies exhibit and dark or intermediate morphs.
In any case, the big “take home message” here is that very dark birds (from light intermediate on up to dark) encountered anywhere in the U.S. are very likely to be one of the two western subspecies: harlanii or calurus.
So what does all this have to do with the central Ohio bird?
First, this dark intermediate (aka dark rufous) individual is a pretty typical dark rufous Western in all respects. No question about the ID once you dig into the details.
Second, and most intriguing, is that reports of a darker Western (calurus) bird have been surfacing from this area west of Columbus, OH sine February of 2009!!! Given the great rarity of these western birds in the east, I can’t help but wonder this isn’t the same bird returning year after year to the same area during winter!
Third, as far as I can tell, most western (i.e., calurus and harlanii) Red-tailed Hawks that are observed in the east are darker morphs, which understandably stick out like a sore thumb against the backdrop of our entirely light morph Eastern Red-tails (B. j. borealis). But what about light morph western birds (yes, both calurus and harlanii have light morphs!), including Krider’s? How many of these are we overlooking?
Perhaps some day I’ll find the time to put together an informative “crash course” in subspecific Red-tailed Hawk ID, but until that happens, you may want to check out some of the resources below. Additionally, consider purchasing (or acquiring through your local library) the Wheeler Guide to Raptors of Western North America and other raptor-specific field guides that treat these subspecies in detail, and of course make it a point to chase after any western birds that show up in your area and/or pay attention to the local Red-tails next time you find yourself west of the Central Time Zone.
Related Online Resources:
Iron, J. Dark morph Red-tailed Hawk: calurus or abieticola? TOC Newsletter, February 2012, Toronto Ornithological Club. http://www.jeaniron.ca/2012/darkredtailsTOCNews.pdf
Liguori, J., and B. Sullivan. 2010. Comparison of Harlan’s with Western and Eastern Red-tailed Hawks. Birding 42(2)2:30-37. http://www.aba.org/birding/v42n2p30.pdf
Liguori, J. 2004. Dark Red-tailed Hawks. Birding 36(3): 278-83. http://www.aba.org/birding/v36n5p500.pdf
Pittaway, R. 1993. Subspecies and Morphs of the Red-tailed Hawk in Ontario Birds 11(1): 23-29. Ontario Field Ornithologists. http://www.jeaniron.ca/2010/redtailsRF.pdf