5482, ♀. ½
In studying the F. lanarius, I have experienced most discouraging difficulties from the want of sufficient series of the Old World races, and from the unsatisfactory character of most descriptions and figures of them, besides being much perplexed by the confusion of their synonymy by different authors. In consequence of this, my diagnoses of the four races of which alone I have seen examples may be very unsatisfactory as regards the characters by which they may be most readily distinguished. Having seen the adult of only a single one of these four races, I am therefore compelled to base my differential characters upon the immature stages.
In addition to the four races of F. lanarius characterized above, there are several geographical forms belonging to the Old World, chiefly intertropical Asia and Africa. These are the var. babylonicus, Scl. and Irby, (Gray’s Hand List, I, p. 20, No. 173,) of Southeastern Europe and Western Asia; var. barbarus, L. (Gray’s Hand List, p. 20, No. 174), of Northern Africa; and var. tanypterus, Licht. (Gray’s Hand List, No. 175), of both the preceding regions, which Mr. Gurney writes me “is simply the intertropical race of F. lanarius, from which it only differs in being of a darker shade throughout.” The F. saker, Schleg. (Gray’s Hand List, No. 176), seems, to judge from the descriptions and figures which I have seen, to be also merely a form of the same species, but I have seen no specimens of it.
Falco (Hierofalco) gyrfalco, Linn.
Var. candicans, Gmelin.
WHITE GERFALCON.
Accipiter falco freti hudsonis, Bris. Orn. I, 356, 1763. A. gyrfalco, Briss. Orn. I, 370, pl. xxx, f. 2, 1763. Falco rusticolus, Fabr. Faun. Grœn. p. 55, 1780.—Lath. Syn. Supp. I, 15, 1781. F. candicans, Gmel. Syst. Nat. p. 275, 1788.—Daud. Tr. Orn. II, 101, 1800.—Benick, Isis, 1824, 882.—Schleg. Krit. Ubers. p. 1, 1844.—Bonap. Rev. Zool. 1850, 484; Consp. Av. p. 33.—Cassin, Proc. Ac. Nat. Sc. Phil. 1855, 278; Birds N. Am. 1858, 13.—Strickl. Orn. Syn. I, 77, 1855.—Blasius, Cab. Jour. 1862, 43 (thinks all boreal ones same in Europe and America).—Elliot, Birds N. Am. pl. xii. Hierofalco candicans, Cuv. Reg. An. ed. 1, I, 312, 1817; ed. 2, I, 323, 1829.—Less. Man. Orn. I, 80, 1828; Tr. Orn. p. 97, pl. xvi, p. 2.—Gray, Hand List I, 18, 1869. Falco islandicus, Lath. Ind. Orn. p. 32, 1790; Syn. I, 71, A, B; Gen. Hist. I, 72, A, 1821.—Steph. Zool. XIII, pt. ii, p. 39, 1826.—Gould, B. Eur. pl. xix.—Aud. Birds Am. 1831, pl. ccclxvi. F. buteo β, Lath. Ind. Orn. p. 24, 1790; Gen. Hist. I, 80, A. F. lagopus, β, Lath. Ind. Orn. p. 19, 1790; Syn. Supp. I, 36; Gen. Hist. I, 68, A. F. grœnlandicus, Daud. Tr. Orn. II, 157, 1800. Hierofalco grœnlandicus, Brehm. Voy. Deutsch, I, 16, 1831. F. gyrfalco, Bonap. List, p. 4, 1838.
Sp. Char. Adult (♀, 18,577, Greenland; Univ. Zool. Mus. Copenhagen). Ground-color entirely pure white; whole upper surface (posterior to the nape) with transverse crescentic bars of dark plumbeous-brown, generally about two on each feather, the first concealed by the feather which overlaps. Primaries crossed at regular intervals with quadrate spots of the same tint, these becoming fused toward ends of quills, forming a terminal dusky space of two or three inches in extent; tips of all the quills narrowly white; the black bars do not extend quite to the primary coverts, and decrease both in extent and regularity toward the base. Middle tail-feathers crossed with seven or eight imperfect bars of dusky, the shafts of the feathers blackish; rest of tail immaculate, the shafts pure white. Nape with a very few fine shaft-streaks of dusky. Whole lower surface of body and wing utterly immaculate. Wing-formula, 2–3–1. Wing, 16.50; tail, 9.00; culmen, 1.05; tarsus, 2.10–1.35; middle toe, 2.20; inner, 1.50; outer, 1.50; posterior, 1.00.
(No. 56,152, ♀, Greenland; Schlüter Collection.) Head above, occiput, nape, and upper half of ear-coverts, with sparse shaft-streaks of black, these most numerous on the latter region; primaries barred to the coverts. Tail entirely crossed by eleven plumbeous bars. Bars above clearer plumbeous. The snowy-white beneath is relieved by a few minute variable flecks of dusky upon the lower part of the abdomen, becoming larger as they approach the sides. Wing-formula, 2–3–1. Wing, 16.70; tail, 9.30.
Juv. transition stage? (♂ 56,047, “Hoher Norden”; Schlüter Collection). Markings above quite different from those of the two preceding; each feather has a large central longitudinal sagittate spot of dusky, leaving only the borders (of the exposed portion) white; on the primaries the dusky is almost confined to the terminal portion; the rump and upper tail-coverts have each feathers with a medial longitudinal stripe of dusky. The tail is immaculate, but the shafts of the middle feathers are dusky. The neck, breast, abdomen, and sides have numerous cuneate marks of dusky, one near the end of each feather. The lining of the wing, even, has a few narrow streaks. Wing, 14.75; tail, 9.40.
No. 56,049 (♀, Greenland, Schl. Coll.) is similar in pattern of markings, but above the dusky is more extended, forming the predominating color; the rump, etc., has broad sagittate spots instead of narrow stripes; the primaries are barred to the coverts; the tail is crossed by about ten continuous bands of dusky. Beneath the lanceolate spots or streaks cover the whole surface, except the anal region, lower tail-coverts, and throat. On the lining of the wing the streaks are less sparse than in the preceding, though they are by no means numerous. Wing, 15.75; tail, 9.50.