The Red-tailed Hawk in Tennessee
This is an article that I wrote for the September 2023 edition of The Migrant (the quarterly scientific journal of Tennessee birds):
The Red-tailed Hawk (Buteo jamaicensis) is one of the most familiar and well known raptor species in the state of Tennessee, the United States, and in all of North America, possibly second only to our national bird, the Bald Eagle (Haliaeetus leucocephalus) in familiarity. Both Robinson (1990) and Somershoe and Sloan (2015) listed it as a fairly common permanent resident in Tennessee. Although the species is a permanent resident in the state, there is a noticeable influx of birds that occurs in the fall, beginning in October. These birds that arrive to spend the winter normally depart by early April. There are two age classes, adult and first year. The species has up to 16 subspecies recognized by various Red-tailed Hawk experts (Preston and Bean 2009). Within each subspecies there are various color morphs (races), making the Red-tailed Hawk the most variable and polymorphic of all North American raptor species (Liguori 2004). In this article I will explore the four recognized subspecies that occur in Tennessee and discuss color morphs and plumage characteristics of each.
Eastern Red-tailed Hawk (B. j. borealis)
The Eastern Red-tailed Hawk is by far the most common subspecies that occurs within the state and is the only subspecies that breeds here. Locally breeding adults are non-migratory (Nicholson 1997). The Eastern subspecies is monotypic and occurs in only light morph plumage. Typical adults have lightly marked underwings, whitish throats, and brick red tails that have very little or no banding save for a black sub-terminal band. Most adults are pale below with a darker belly band, dark wing tips and dark edging to the flight feathers. First year birds are typically lightly marked underneath with light throats and brownish belly bands. The head is generally lighter than on adults and the tail is light brown or tan with narrow darker bands. On both adults and first year birds, the dark patagial bar on the leading edge of the wing is obvious and diagnostic. During the colder months, beginning in October, we get an influx of Eastern Red-tailed Hawks from the states and Canadian provinces to our north that arrive in Tennessee to spend the winter. Eastern Red-tailed Hawks from the most northern parts of their range are often more heavily marked below than our typical resident birds are.
Fig. 1. A “classic” adult Eastern Red-tailed Hawk with a pale throat, minimal bellyband, light brown head, and unbanded red tail. Gibson County, 5 February 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/69095576
Fig. 2. Dorsal view of an adult Eastern Red-tailed Hawk showing the dark eye and “classic” unbanded red tail. This individual even lacks a black subterminal band. Lake County, 18 August 2020. Photo by Mark A. Greene. https://www.inaturalist.org/observations/56971903 (photo #2)
Fig. 3. First year juvenile Eastern Red-tailed Hawk showing light head and banded light reddish brown tail. Gibson County, 4 March 2023. Photo by Tricia Vesely. https://www.inaturalist.org/observations/234158972
Northern Red-tailed Hawk (B. j. abieticola)
The Northern Red-tailed Hawk is the next most numerous subspecies that occurs within the state but is probably the one that is least known by most birders. This subspecies is a winter resident in the state. It is uncommon in West Tennessee, becoming rarer as you go east in the state. Wintering birds often return to the same areas each fall. Part of the reason that this subspecies is not more well known by many birders is that it has only become a widely accepted subspecies in recent years (Liguori and Sullivan 2014). Some experts still classify these birds as heavily marked Eastern Red-tails (Wheeler 2003) but that reasoning has lost some traction in recent years as our understanding of these birds has grown. In the past, light morph Red-tailed Hawks with heavily marked underparts that arrive in Tennessee during migration and winter have been called Western Red-tailed Hawks (B. j. calurus) but further research reveals that these individuals are actually Northern Red-tailed Hawks instead. W. E. Clyde Todd first described the abieticola subspecies in “A Northern Race of Red-tailed Hawk” (1950). He noted that the differences from the Eastern Red-tailed Hawk were a dark throat, more richly colored underparts, and a heavier bellyband. The underparts are also generally more heavily streaked, upperparts darker colored, and patagial marks are darker and thicker. Dickerman and Parks (1987) also noted that the bellyband generally has “bold, heavy, dusky to black streaking” which differs from both borealis and calurus. First year light morph abieticola are similar to borealis but are typically more heavily marked on the belly and underwings. It is also now believed by many raptor experts that this subspecies is polytypic and that there are also dark and intermediate (rufous) morph abieticola (Liguori et al. 2020). The reasoning for this is this is that throughout the range of the Western (calurus) Red-tailed Hawk, dark and intermediate (rufous) morph calurus only make up about 15% of the population (HawkWatch International). In Tennessee and throughout the Eastern United States what we once thought to be light-morph Western Red-tailed Hawks (calurus) in migration and during the winter have turned out to be Northern Red-tailed Hawks (abieticola). In fact, the author could not find one single photograph of a light-morph calurus from Tennessee in the Macaulay online library of photos submitted to eBird. In contrast, there are numerous photos of dark and intermediate (rufous) morph, non-Harlan’s, Red-tailed Hawks from Tennessee there. In polytypic Red-tailed Hawk subspecies light-morphs are much more numerous than dark-morphs, yet we see no light morph calurus in Tennessee. Based on that fact, it would then stand to reason then that these dark morph birds are not calurus. Extensive research is now being done by the Red-tailed Hawk Project in the way of banding and GPS tagging of dark morph Red-tailed Hawks in the Eastern, Central, and Southeastern United States to help unravel this mystery. For the purpose of this article, the author will consider dark and intermediate (rufous) morph, non-Harlan’s, Red-tailed Hawks in Tennessee to be dark abieticola. Most of the dark birds seen in Tennessee in the winter months are dark intermediate morph (also called rufous morph) and have an upper breast that is dark rufous in color when seen in good light. The belly below is blackish. True dark morphs are rarely seen in Tennessee and are a uniform dark chocolate brown on the breast and belly.
Fig. 4. Perched adult light morph Northern Red-tailed Hawk with a mostly dark throat, rufous-washed upper breast, and dark, heavy bellyband. Gibson County, 24 February 2022. Photo by Mark A. Greene. https://www.inaturalist.org/observations/107644609
Fig. 5. In flight shot of same bird as in Fig. 4, showing thick, dark patagial bars, rufous-washed, streaked breast, dark, blobby bellyband, and thick subterminal band on the tail. Gibson County, 11 December 2020. Photo by Steve Yarbrough. https://www.inaturalist.org/observations/234159642
Fig. 6. In flight shot of a first year light morph juvenile Northern Red-tailed Hawk showing heavily marked underparts and underwings and a streaked throat. Crockett County, 23 November 2020. Photo by Mark A. Greene. https://www.inaturalist.org/observations/65496933
Fig. 7. Adult dark intermediate (rufous) morph Northern Red-tailed Hawk perched on the cross arm of an electric utility pole showing the rufous colored upper breast and darker belly. This bird has returned to the same general area for several consecutive winters. Gibson County, 17 December 2020. Photo by Mark A. Greene. https://www.inaturalist.org/observations/66709630
Fig. 8. Same bird as in Fig. 7 showing banded red tail with a thick subterminal band. Gibson County, 19 December 2022. Photo by Mark A. Greene. https://www.inaturalist.org/observations/145198876
Fig. 9. Flight shot of an adult dark intermediate (rufous) morph Northern Red-tailed Hawk. Lake County, 16 March 2023. Photo by Mark A. Greene. https://www.inaturalist.org/observations/151338415
Fig. 10. First year juvenile dark morph Northern Red-tailed Hawk with brownish banded tail and light eyes. Lake County, 22 November 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/101761536
Harlan’s Red-tailed Hawk (B. j. harlani)
The Harlan’s Red-tailed Hawk is a rare winter resident in the Western Coastal Plain Region and an accidental winter visitor in the rest of the state. Harlan’s are known to return to the same general wintering locations year after year. This subspecies is the most variable in plumage of all the Red-tail subspecies with birds ranging from a ghostly white to completely black below (Liguori and Sullivan 2018). The majority of dark-morph birds have some white mottling on the breast and these are sometimes called intermediate morphs or dark intermediate morphs depending on the amount of mottling (Wheeler 2003). Adult birds are identified by their overall cold color tones (more black than brown) and uniquely mottled tail pattern – typically whitish, grayish, brownish, or blackish mottled, but some may show a varying amount of red. A small percentage of dark adults show a full or partial black-and-white banded tail (Clark 2009), though these birds might be intergrades with other subspecies. Most adult birds lack banding in the primaries and secondaries. First year juvenile dark morph birds range from streaked to solid dark below, have banded outer primaries, and the tail tips show a “spiked” look (Liguori and Sullivan 2018). Primaries and upper wing coverts have black and white spangling.
Light-morph Harlan’s make up 8-12% of all Harlan’s (Liguori and Sullivan 2010). Light-morph Harlan’s are identified by snow-white body plumage lacking warm, buffy tones, dark, “blobby” belly markings, a white throat & supercilium, and lightly marked underwing coverts. The head generally lacks the golden brown hue of other light subspecies and may be white or streaked with white on the crown (Liguori and Sullivan 2010). They are most likely to be confused with lighter Eastern Red-tailed Hawks and Krider’s Red-tailed Hawks (B. j. kriderii). First-year light-morph Harlan’s have white wing panels and extensive white mottling along the upper wing coverts (Liguori and Sullivan 2018).
Fig. 11. Adult dark intermediate-morph Harlan’s Red-tailed Hawk showing dark body with white feathering on breast and grayish-white mottled tail. Dyer County, 14 March 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/71310608
Fig. 12. Adult intermediate-morph Harlan’s Red-tailed Hawk showing extensive white feathering on otherwise blackish body. This is a young adult bird that still has light eyes. Lake County, 21 February 2023. Photo by Mark A. Greene. https://www.inaturalist.org/observations/149359220
Fig. 13. Juvenile intermediate morph Harlan’s Red-tailed Hawk showing white mottling on dark body, wing primaries banded to the tip, wavy bands on the tail, and a “spiked” look to tail feathers. Shelby County, 28 November 2023. Photo by Tricia Vesely. https://www.inaturalist.org/observations/234159996
Fig. 14. Perched adult intermediate morph Harlan’s Red-tailed Hawk showing dark body plumage, white throat, and white mottling on breast. Gibson County, 15 March 2022. Photo by Mark A. Greene. https://www.inaturalist.org/observations/108727882
Fig. 15. A very cryptic looking adult light morph Harlan’s Red-tailed Hawk. On first glance this bird might be confused with an Eastern Red-tailed Hawk but note the overall cold tone of the bird (generally more black and white in overall color, lacking warm tones), the dark, blobby bellyband, streaked crown, and mottling in the tail. This bird has returned to the same area to winter for several years. Gibson County, 30 December 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/104431718
Fig. 16. Flight shot of same bird in Fig. 15. Note classic Harlan’s gray-white tail with mottling, dark, “blobby” bellyband, overall cold tones, and streaked crown. Gibson County, 10 November 2020. Photo by Mark A. Greene. https://www.inaturalist.org/observations/64604776
Fig. 17. Juvenile light morph Harlan’s Red-tailed Hawk showing overall cold tones, dark, blobby bellyband, a streaked crown, and very light head. Lake County, 26 January 2022. Photo by Mark A. Greene. https://www.inaturalist.org/observations/105682758
Krider’s Red-tailed Hawk (B. j. kriderii)
The Krider’s Red-tailed Hawk is a rare winter resident in the Western Coastal Plain Region and accidental elsewhere in the state. Much like other subspecies that winter in Tennessee, many Krider’s are known to return to the same general areas each fall to spend the winter. The Krider’s subspecies is a very pale subspecies (only occurring as a light morph) with an almost absence of markings below except for small, darker wrist commas and faint patagial bars which are often rufous-tinged in color. Krider’s are mostly white headed, usually with a distinct darker malar (Liguori and Sullivan 2010). The tail is usually white, especially on the basal half, normally with a dark subterminal band. The upperwings usually show extensive white mottling. Juveniles are very similar in plumage, although frequently even paler, especially on the head, except they have narrow dark bands on the tail. The taxonomic status of this subspecies in still unclear, with some authorities treating it as a full subspecies (AOU 1957) and others treating it as an extremely pale form of B. j. borealis (Wheeler 2003). Whatever it’s true classification is, it is a distinctive population, and for purposes of this article it will be treated as such. Many Krider’s have plumage characteristics that are somewhat intermediate and these are likely intergrades with other subspecies that still have several prominent Krider’s field marks.
Fig. 18. Perched adult Krider’s Red-tailed Hawk showing minimal bellyband, white throat, extensive white on head and white mottling on upper wing. Obion County, 3 November 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/100188625
Fig. 19. Dorsal view of same bird from Fig. 18, showing extensive white in the tail and white mottling on the upper wings. Obion County, 21 January 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/68425371
Fig. 20. Adult Krider’s Red-tailed Hawk in flight showing nearly absent bellyband, faint patagial bars, white throat, and extensive white on head with a dark malar. Obion County, 10 March 2023. Photo by Mark A. Greene. https://www.inaturalist.org/observations/150770639
Fig. 21. Juvenile Krider’s Red-tailed Hawk in flight showing extensive overall paleness, minimal bellyband, faint patagial bars, whitish head and throat. Fulton County, KY (just north of the TN state line), 2 November 2023. Photo by Mark A. Greene. https://www.inaturalist.org/observations/189811323 (photo #1)
Fig. 22. Dorsal view of the same juvenile bird from Fig. 21 showing whitish head, extensive white in the tail, and white mottling on upper wings and back. Fulton County, KY (just north of the TN state line), 2 November 2023. Photo by Mark A. Greene. https://www.inaturalist.org/observations/189811323 (photo #2)
Intergrading, etc.
The ranges of Red-tailed Hawk subspecies overlap in many areas and in these areas interbreeding between subspecies is common and produces a variety of intergrades. Many simply cannot be classified (Lish 2015), and this is especially true for juveniles. Intergrades may show the phenotypic characteristics of more than one subspecies or may be more general in appearance not showing strong traits of any one subspecies. Some may check several boxes for one specific subspecies but not quite enough to categorize them completely as such. Fig. 23 and 24 show some examples of this. Caution should always be exercised when identifying Red-tailed Hawks to subspecies but with experience and careful consideration many Red-tails can be categorized to the subspecies level.
For reporting on websites such as eBird, observers may report Red-tailed Hawks to the subspecies level if they are confident of their identification. It is always advisable to simply report the bird as a Red-tailed Hawk species if not certain of the subspecies. For more experienced observers, it is okay to report intergrades that show stronger characteristics of one particular subspecies as that subspecies, even if the bird shows some characteristics of intergrading (Brian Sullivan, pers. comm.). For example, the birds in both Fig. 23 and 24 were reported on ebird and iNaturalist as harlani.
Fig. 23. This adult Red-tailed Hawk shows many of the characteristics of a light morph Harlan’s Red-tailed Hawk (cold tones, white around the eyes, dark, “blobby” bellyband, streaked crown) but the tail is red and banded and shows no mottling typical of the Harlan’s subspecies. I suspect that this bird is a harlani that has intergraded with another subspecies, perhaps abieticola. Crockett County, 26 October 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/99550728
Fig. 24. At first glance, this adult dark morph Red-tailed Hawk might be passed off as a dark morph Northern Red-tailed Hawk (abieticola) but note the extensive white in the tail not normally seen in that subspecies. That feature plus the general lack of warm tones on this bird seem to indicate that this bird is a harlani that has intergraded with abieticola or possibly calurus. Obion County, 16 March 2021. Photo by Mark A. Greene. https://www.inaturalist.org/observations/71427237
Acknowledgements
I wish to thank David Pitts, Bob Ford, and Michael Todd for helpful comments during the writing of this manuscript. I want to thank Tricia Vesely and Steve Yarbrough for the use of their photos. Thanks also goes to Mike Borle’, Shane Brown, Gail Bruckner, Bonnie Cleaver, Bryce Robinson, Cathy Sheeter, and Brian Sullivan for their contributions in broadening my understanding of Red-tailed Hawk subspecies by their comments on social media platforms, personal communications, etc. I also owe a big debt of gratitude to the late Jeff R. Wilson who sparked my interest in these majestic raptors by encouraging me to “look closely at every Red-tailed Hawk” during the winter months.
Bibliography
American Ornithologists’ Union (AOU). 1957. Check-list of North American Birds, fifth edition. Lord Baltimore Press, Baltimore.
Clark, William S. 2009. Extreme Variation in the Tails of Adult Harlan’s Hawks. Birding 41:30-36.
Dickerman, R. W. and K. C. Parkes. 1987. Subspecies of the Red-tailed Hawk in the Northeast. Kingbird 37:57-64.
eBird. https://www.ebird.org. Accessed 21 March 2023.
HawkWatch International. https://hawkwatch.org/learn/factsheets/item/104-redtailed-hawk. Accessed 23 March 2023.
Liguori, Jerry. 2004. Dark Red-tailed Hawks. Birding 36:500-506.
Liguori, Jerry and Brian Sullivan. 2010. A Study of Krider’s Red-tailed Hawk. Birding 42:38-45.
Liguori, Jerry and Brian Sullivan. 2010. Comparison of Harlan’s with Western & Eastern Red-tailed Hawks. Birding 42:30-37.
Liguori, Jerry and Brian Sullivan. 2014. Northern Red-tailed Hawk (Buteo jamacaicensis abieticola) revisited. North American Birds 67:374-383.
Liguori, Jerry and Brian Sullivan. 2018. HawkWatch International, Inc. Raptor ID. (Vers. 1.0.6). [Mobile app]. App Store. https://apps.apple.com/us/app/raptor-id/id1033944000
Liguori, Jerry, Jesse L. Watson, Frank Nicoletti, and Dave Oleyear. 2020. In-hand Guide to Diurnal North American Raptors. HawkWatch International, Inc.
Lish, Jim. 2015. Winter’s Hawk: Red-tails on the Southern Plains. University of Oklahoma Press, Norman.
Macaulay Library. https://www.macaulaylibrary.org. Accessed 23 March 2023.
Nicholson, Charles P. 1997. Atlas of the Breeding Birds of Tennessee. University of Tennessee Press, Knoxville.
Preston, C. R. and R. D. Beane. 2009. "Red-tailed Hawk (Buteo jamaicensis), in A. Poole, ed. The Birds of North America Online. Cornell Laboratory of Ornithology, Ithaca
Red-tailed Hawk Project. https://redtailedhawkproject.org. Accessed 22 March 2023.
Robinson. John C. 1990. An Annotated Checklist of the Birds of Tennessee. University of Tennessee Press, Knoxville.
Somershoe, Scott G. and Christopher A. Sloan. 2015. Birds of Tennessee: A New Annotated Checklist. Privately published.
Todd, W. E. C. 1950. A Northern Race of Red-tailed Hawk. Annals of the Carnegie Museum (Pittsburgh) 31:289-296.
Wheeler, Brian K. 2003. Raptors of Western North America. Princeton University Press, Princeton.
