SP. CHAR. Form robust and strong, like _B. borealis_; wings long and pointed; only three outer primaries with their inner webs cut. Feet robust, the tarsi strong. Dimensions: Wing, 14.40–17.00; tail, 8.00–9.50; culmen, .80–.95; tarsus, 2.30–2.70; middle toe, 1.50–1.70. Weight, 1½–3½ lbs. Colors: Tail dark grayish-brown with a hoary cast, crossed by numerous obscure narrow bands of a darker shade. _Adult_, uniform blackish-brown above; upper tail-coverts barred with white. Throat and lower parts posterior to the breast white or pale ochraceous; a broad patch across the breast uniform brown,—reddish-rufous in the male, and grayish-umber in the female,—the whole lower surface varying to entirely uniform dull brownish-black, though intermediate shades. _Young_, with the ground-color of the plumage soft ochraceous, or cream-color; the head, neck, dorsal region, and sides of the breast, with tear-shaped spots of brownish-black, with a faint purple reflection. Upper parts purplish-black, variegated with ochraceous, sometimes almost wholly black. Tail as in the adult, but more hoary. _a._ _Normal plumage._ _Adult male_ (53,105, Truckee River, Nevada, July; C. King, R. Ridgway). Head, neck, and upper parts blackish-brown; scapulars slightly variegated with a rufous mottling; upper tail-coverts white tinged with rufous, and with transverse bars of blackish-brown, about six on each feather. Tail dark brown like the back, approaching black terminally, basally with a slight hoary cast; crossed by about ten narrow, very obscure bands of nearly black. Front and whole throat clear white, immaculate, and sharply defined against the surrounding blackish; lores dusky. Whole breast, cinnamon-rufous (forming a wide, sharply defined band), marked laterally with the brown of the neck; each feather with a shaft-line of black; rest of lower parts, including whole lining of the wing, continuous ochraceous white, the latter region unvariegated; sides with sparse, faint, transverse bars of rufous, and shaft-lines of darker. Under side of primaries light slate anterior to emargination, beyond which they are black; slaty portion crossed by very obscure bars of darker. Fourth quill longest, third scarcely shorter; second equal to fifth; first intermediate between seventh and eighth. Length, 19.75; extent, 48.00; wing, 15.40; tail, 8.00; tarsus, 2.32; middle toe, 1.60. (Weight 1½ lbs.) Bill slate-black, bluish basally; cere, and angle of mouth, light dull lemon yellow; iris deep hazel; tarsi and toes deep chrome yellow, claws black. [Illustration: =58505=, ♀. ½ =58505=, ♀. ½ _Buteo swainsoni_ (Nevada).]