Western Red-tailed Hawk

In wing chord males range from 354 to 404 mm (13.9 to 15.9 in), averaging 386.8 mm (15.23 in), and females range from 386 to 428 mm (15.2 to 16.9 in), averaging 411.2 mm (16.19 in). males and females average 224.2 and 237.3 mm (8.83 and 9.34 in) in tail length, 85.4 and 88.1 mm (3.36 and 3.47 in) in tarsal length and 25.1 and 27.4 mm (0.99 and 1.08 in) in culmen length. The two largest samples of body mass in B. j. calurus showed that in Idaho, around the greater area of the Snake River NCA, 90 males averaged 957 g (2.110 lb) and 113 females averaged 1,150 g (2.54 lb), while 152 migrating B. j. calurus at the Goshute Mountains of Nevada averaged 933.4 g (2.058 lb). Adult B. j. calurus are usually rangier and darker than the eastern red-tailed hawk (B. j. borealis), with pale individuals usually having a richer tawny base color (with occasionally a pale rufous color showing around the chest or neck), typically a heavily streaked breast and belly band, a brownish throat, dark barring on the flanks, a well-defined tawny V on the back and, occasionally, a tail with multiple bars. Dark morph B. j. calurus adults are typically all chocolate brown above and below (although sometimes variously even jet black or with a bit of tawny feather edging below) with a rufous tail, which sometimes has heavy blackish crossbars but is usually similar to other red tails. Intermediate or rufous morphs are rich rufous on the breast, with a broad, solid chocolate-brown belly band and heavily barred thighs and crissum. Like dark morphs, rufous morph adults usually lack the incomplete V on the back, but sometimes rufous feathers can manifest on one. Adults may show nearly endless variation in coloring and many may combine several characteristics of the three main morphs. Dark morph juveniles are usually mostly dark brown but with extensive pale mottling on the back and occasional tawny-edge feathers on the underside and slightly broader bars on the tail than pale morph B. j. calurus. Rufous morph immatures are more similar to pale morph ones but are considerably more heavily streaked almost everywhere below from the thighs to the upper chest. Individuals of northwestern Mexico may average paler than most B. j. calurus, lacking the typical dark wing markings.