Harlan's hawk

Harlan's hawk or Harlan's red-tailed hawk (''Buteo jamaicensis harlani'') Website based on / supplement to book, is a subspecies of the red-tailed hawk.

Description

While similar in linear dimensions to the western red-tailed hawk (''B. j. calurus''), this race is sometimes described as slighter and lighter.Dunne, P.; Sibley, D. & Sutton, C. (1988). ''Hawks in Flight: The Flight Identification of North American Migrant Raptors''. Houghton Mifflin Harcourt. On the contrary, though, they are highly sexually dimorphic in size (the most dimorphic of any in the United States) and mature females are sometimes more massive than almost any female ''B. j. calurus''.Palmer, R. S. ed. (1988). ''Handbook of North American Birds''. Volume 5 Diurnal Raptors (Part 2). However, ''B. j. calurus'' tends to have a much longer tarsus than Harlan's hawks do, as expected due to the latter's habitation to cold environments almost year around.Clark, W. S. (2014)
"Harlan's Hawk differs from Red-Tailed Hawk"
. Global Raptor Information Network. The wing chord of males can range from , averaging , and, in females, it ranges from , averaging . Males and females average in tail length, in tarsal length and in culmen length.Ridgway, R. & Friedmann, H. (1919). ''The Birds of North and Middle America: A Descriptive Catalogue of the Higher Groups, Genera, Species, and Subspecies of Birds Known to Occur in North America, from the Arctic Lands to the Isthmus of Panama, the West Indies and Other Islands of the Caribbean Sea, and the Galapagos Archipelago''. Vol. 50, No. 8. Govt. Print. A wintering female in eastern Kansas weighed .

The historic taxonomic status of Harlan's hawk has been quite erratic; sometimes, it has been classified as its own species, ''B. harlani'' to the opposite extreme that R. S. Palmer (1988) classified as it (perhaps improbably) as a mere western color morph. Most modern authorities recognize Harlan's hawk as a valid subspecies. Harlan's hawk is markedly different from all other red tails and can be identified nearly 100% of the time by an experienced hawk watcher. Throughout the morphs of this subspecies, the plumage is predominantly blackish, lacking any warmer or brownish tones (save the tail). Harlan's hawks usually have faint streaks on the sides of their head and about their chest with a bit of gray mottling or speckling on the scapulars. Apart from a variably white-streaked throat, their underparts are usually mostly black with variable white streaking and barring on the thighs or crissum. There are up to four main variations from the typical one described above: extreme dark morph (where even the throat is black and no pale streaking is present), dark morph (with barring still present from the tarsus to the underside), rare pale morph (with few blackish blobs on the belly and generally a whiter head) and perhaps even rarer types, the base color of which is grayish. Unlike most red-tailed hawks, immatures are generally similar enough to adults that it can be difficult to distinguish them. On average, immatures have more extensive pale streaking above and mottling below, but much individual variation has been recorded. The typical tail of a Harlan's hawk is white with a thick black subterminal band but individuals may vary considerably and the tail may be reddish, dusky, whitish or gray and can be longitudinally streaked, mottled or barred.

Distribution

It breeds from central Alaska to northwestern Canada, with the largest number of birds breeding in the Yukon or western Alaska, reaching their southern limit in north-central British Columbia. Harlan's hawk is restricted as a breeder to pure taiga habitat. Harlan's hawk winters from Nebraska and Kansas to Texas and northern Louisiana, with a rare bird found as far east as Tennessee.Preston, C. R. & Beane, R. D. (2009). "Red-tailed Hawk (''Buteo jamaicensis'')". ''The Birds of North America''. .Johnsgard, P. A. (1990). ''Hawks, Eagles, & Falcons of North America: Biology and Natural History''. Smithsonian Institution.Taverner, P. A. (1927). "A study of ''Buteo borealis'', the Red-tailed Hawk, and its varieties in Canada (No. 13)". Canada. Victoria Memorial Museum.

References

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Harlan's hawk