Part 68

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, and the other, also shot from nest of two eggs, near Pelican Lake, Minn., May 21, 1872) 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) 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.).

Var. lucasanus, RIDGWAY.

ST. LUCAS RED-TAIL.

“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 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.).

Localities quoted: (?) Xalapa (SCLATER, P. Z. S. 1859, 368); Oaxaca (SCL. P. Z. S. 1859, 389); (?) Cuba (CAB. Journ. II. lxxxii; GUNDL. Rep. 1865, 223; resident. “B. borealis”); S. E. Texas (DRESSER, Ibis, 1865, 324).

LIST OF SPECIMENS EXAMINED.

National Museum, 44; Philadelphia Academy, 18; Boston Society, 6; Coll. G. N. Lawrence, 2; R. Ridgway, 5. Total, 75.

Measurements.

+----+-----------+-----------+---------+---------+-----------+-----------+ |Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.| Specimens.| +----+-----------+-----------+---------+---------+-----------+-----------+ | ♂ |13.50–16.00| 9.50–10.00| .90–1.10|2.90–3.30| 1.70–1.80| 30 N. Am.| +----+-----------+-----------+---------+---------+-----------+-----------+ | ♀ |16.00–17.25| 9.50–11.30|1.00–1.08|3.30–3.40| 1.80–1.95| 16 N. Am.| +----+-----------+-----------+---------+---------+-----------+-----------+ | ♂ |13.25–14.00| 9.00–0.00|1.00–0.00|3.30–0.00| 1.80–0.00|2 Jamaican.| +----+-----------+-----------+---------+---------+-----------+-----------+ | ♀ | 14.50–0.00| 9.00–0.00|1.10–0.00|3.25–0.00| 1.75–0.00|1 Jamaican.| +----+-----------+-----------+---------+---------+-----------+-----------+ | ♂ | 15.50–0.00| 9.50–0.00|1.15–0.00|3.10–0.00| 1.85–0.00| 1 Cuban.| +----+-----------+-----------+---------+---------+-----------+-----------+

A large collection of specimens of this race presents a series connecting borealis with the black form known as “calurus”; every possible condition between the two being indicated in the range of individual variation. The lightest styles as distinguished from var. borealis always have the tibiæ barred with rufous; the crissum, also, is generally barred, on the throat the blackish-brown predominates, and the tail has more or less perfect bars to the roots of the feathers; generally, however, these are merely indicated by projections from the shafts.

The extreme condition of this is the melanistic form which Mr. Cassin described as “Buteo calurus”; the darkest example of which (5,481, Petaluma, Cal.; E. Samuels) is entirely blackish-brown, wings and scapulars with feathers somewhat paler at tips; breast inclining to dark sepia-brown, the feathers with black shaft-streaks; tibial feathers faintly tipped with pale grayish-brown; lower tail-coverts tipped and barred with rufous; upper tail-coverts deep rufous barred with black; tail deep chestnut-rufous, the subterminal black band very broad, and anterior to this are nine or ten imperfect narrower black bands.