“Buteo borealis var. lucasanus, Ridgway,” Coues, Key, 1872, 216 (under B. borealis).
Sp. Char. Adult. General appearance of the normal plumage of var. calurus, but the upper parts more uniformly blackish, and the upper tail-coverts and tail uniform rufous, the latter without a trace of a black bar. Beneath nearly uniform reddish ochraceous, or light rufous, the usual abdominal belt merely indicated by a few inconspicuous spots; no trace of transverse bars on the lower parts. Female ? (No. 16,925, Cape St. Lucas, Sept. 15, 1859; J. Xantus). Wing, 16.00; tail, 9.50; tarsus, 3.00; middle toe, 1.60. Wing-formula 5, 4, 3, 2–6–7–8–9, 1, 10.
Young. Not distinguishable, by positive characters, from that of var. calurus.
Hab. Peninsula of Lower California.
All adult specimens from the peninsula of Lower California agree with that described above, in the peculiar features which I consider as characterizing a well-marked local race. The present form is most nearly related, in its adult dress, to the var. krideri of the plains, in its unbarred tail and immaculate lower plumage, but differs from this in having the upper parts nearly black instead of almost white, the upper tail-coverts deep rufous, like the tail, instead of white, and the lower parts rufous instead of white; in the rufous lower plumage and very dark upper parts, it closely resembles var. costaricensis[90] of Central America and Southern Mexico, but the latter has a barred tail, entirely continuous black above, plain white throat patch, and other minor differences, besides having a quite different young plumage. As to the young plumage of var. lucasanus, I cannot find any character by which it can with certainty be distinguished from that of var. calurus.
Var. calurus, Cassin.
WESTERN RED-TAIL; BLACK RED-TAIL.
Buteo calurus, Cassin, Proc. Acad. Nat. Sc. Phil. VII, 281, 1855; Birds N. Am. 1858, 22.—Strickl. Orn. Syn. I, 38, 1855.—Coues, Prod. Orn. Ariz. p. 8, 1866.—Gray, Hand List, I, 7, 1869. Buteo montanus (not of Nuttall!), Cassin, Birds N. Am. 1858, 26.—Newb. P. R. R. Rept. VI, iv, 1857.—Heerm. P. R. R. Rept. VII, 31, 1857.—Coop. & Suck. P. R. R. Rept. XII, ii, 147, 1860.—Coues, Prod. Orn. Ariz. p. 7, 1866.—Buteo swainsoni (not of Bonap!), Cass. B. Cal. & Tex. p. 98, 1854.
Sp. Char. Adult. Similar to var. borealis, but darker, with more rufous and blackish in the plumage; tibiæ always, and flanks and crissum usually, barred with rufous; throat with the dark streaks suffused and widened, so as to form the prevailing color. Tail with indications of transverse bars anterior to the usual subterminal one, these varying in number and distinctness with the individual. Whole plumage sometimes sooty black, the breast, however, covered by an appreciably paler patch, usually of a somewhat rufous hue. Tail sometimes with regular and continuous narrow bands to the very base.
Young. Very much darker than that of var. borealis, the pattern being similar, but the dark markings much expanded and more numerous; tibiæ with heavy transverse spots of dusky.
Hab. Western region of North America, from the Rocky Mountains to the Pacific; south into Mexico; West Indies (Jamaica and Cuba, Mus. S. I.).