A specimen (No. 1,750, Carlisle, Pa.; S. F. Baird) appears at first sight much like the var. calurus, being very dark; the tibiæ, anal region, and the lower tail-coverts are, however, not barred as in this, and the tail possesses but the subterminal band.
An immature specimen (No. 21,488; John Krider) from Philadelphia has the tibiæ quite distinctly barred, but less conspicuously so than in young of var. calurus.
Var. krideri, Hoopes.
WHITE-BELLIED RED-TAIL.
Buteo krideri, Hoopes, P. A. N. S. Philad. 1873, p. —
Sp. Char. Adult. Similar to var. borealis, but beneath continuous pure white, without rufous tinge, and without distinct spots across the abdomen, or lacking them entirely; above much lighter, the brown, light rufous, and white being about equal in amount. Upper tail-coverts immaculate white; tail pale rufous, the shafts pure white, and the webs mixed with white along their edges, its amount increasing toward the base; no trace of a dusky subterminal bar, or else only indicated by badly defined spots.
Young. Differing from that of var. borealis in the immaculate, snowy-white lower parts, nearly equal extent of the white and dusky on the upper parts, and whitish cast of the tail.
Two females (one shot from nest of two eggs, near Alexandria, Minn., May 8, 1872,[87] and the other, also shot from nest of two eggs, near Pelican Lake, Minn., May 21, 1872[88]) are entirely absolutely pure white beneath, there being but the faintest indications of markings in the region of the usual abdominal belt; even the whole under side of the wing is almost immaculate. The ground-color of the upper parts is pale grayish-brown, about equally variegated transversely, on the scapulars and tertials, with white. In one of them, the sides of the head and neck are pale fawn-color, the “mustache” from the rictus brownish-black in conspicuous contrast; the upper parts are nearly equally variegated with brown, light rufous, and white, the latter predominating posteriorly. The upper tail-coverts are immaculate white. The tail-feathers are light rufous, with pure white shafts, considerably mixed with white along the edges of the feathers, the white considerably increasing towards the base of the tail. Of the subterminal dusky band there is no trace in one specimen, while in the other it is indicated by transverse spots, while the inner webs along the shafts are much variegated with transverse dusky spots. The male specimen (shot at Chippewa Lake, Minn., from nest (!) of two eggs May 19, 1872[89]) is considerably darker, nearly like the average plumage of eastern var. borealis. Still the white of the lower parts is remarkably pure, being of an almost snowy clearness, without any trace whatever of an ochraceous tinge.
No. 8,532, Devil’s River, Texas (Nov. 1855; Dr. C. B. Kennerly), differs only in being a little less pure white beneath, the lower parts being very appreciably tinged with rufous posteriorly.
Hab. Plains of the United States, from Minnesota to Texas (Devil’s River, M. S. I.).