Part 29

Wing, 13.60–14.30; tail, 8.25–9.00; culmen, .80–.87; tarsus, 1.85–1.90; middle toe, 1.85–1.90. Colors similar to the last; entire auriculars white; mustache narrow and conspicuous. Hab. Southern Asia …

var. jugger.

The only point of difference in the external anatomy between the Lanner Falcons and Gerfalcons consists in the different degree of feathering on the upper part of the tarsus; this is much denser and extends farther down and more around the posterior face in the Gerfalcons, but they, being inhabitants of a very northern latitude, need this protection against the rigor of the climate. These slight specific differences are illustrated by the figures on page 1430. The same difference is observable in many birds whose habitat extends through a great range of latitude, as, for instance, the Pediocætes phasianellus, the northern race of which has the feathers covering the base of the toes so long as to reach beyond the claws and nearly conceal them, while in the southern form (var. columbianus) the toes are almost completely naked.

My determination of the number and character of the geographical races of F. gyrfalco is the result of a very careful critical examination of over sixty specimens, aided by the important conclusions of Mr. Hancock (Annals and Magazine of Natural History, 2d ser., XIII, 110; London, 1834), Schlegel (Falcones, Muséum d’Histoire Naturelle des Pays-Bas, 1862), Pelzeln (Uebersicht der Geier und Falken der Kaiserlichen ornithologischen Sammlung, April, 1863), and Alfred Newton (History of British Birds, revised ed., part 1, June, 1871, pp. 36–52, and Proc. Acad. Nat. Sc. Philadelphia, July, 1871, pp. 94, 95), in their important papers bearing upon this subject, which, though they each express the peculiar individual views of the writer, together clear up pretty satisfactorily the problem of the number, character, and habitats of the several races, as well as the different phases of variation to which each is subject.

Falco sacer.]

Falco polyagrus.]

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.

Juv. first plumage (♀, 56,053, Greenland; Schlüter Coll.). All the markings are longitudinal, instead of directly the reverse. The upper parts have longitudinal tear-shaped stripes, a medial one on each feather; they are sparse, however, on the wings; the rump has narrow shaft-lines of dusky. The tail and upper coverts are immaculate, but the shafts of all the feathers are nearly pure black. The bars on the primaries are found only immediately next the dusky terminal space. The streaks beneath are not very numerous, and are found only on the breast, upper part of abdomen, and on the sides; the nape and sides of the neck are, however, thickly streaked.

(No. 17,966, ♀, Moose Factory, Hudson Bay Territory.) In character of markings resembling the last, but the stripes are fainter and narrower; they are also less numerous. On the under parts they are wanting. Unfortunately, the tail of this specimen, which is the only North American one in the collection, is missing.

In all specimens the anal region and lower tail-coverts are immaculate.

HAB. Greenland, and continent of North America, north of Hudson Bay (breeding in latter region). Of irregular occurrence in winter throughout the circumpolar regions; Ural Mountains (EVERSMAN); Behring’s Strait (BANNISTER).

LIST OF SPECIMENS EXAMINED.

National Museum, 7; Boston Society, 2; Philadelphia Academy, 3; New York Museum, 6; collection of R. Ridgway, 1. Total, 19.

Measurements.

+----+-----------+-----------+---------+---------+-----------+----------+ |Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.| +----+-----------+-----------+---------+---------+-----------+----------+ | ♂ |14.40–14.75| 9.70–00.00| .90–0.00|2.15–2.45| 1.95–2.00| 3 | +----+-----------+-----------+---------+---------+-----------+----------+ | ♀ |15.75–16.25|10.00–11.00| .98–1.00|2.20–2.50| 2.05–2.15| 6 | +----+-----------+-----------+---------+---------+-----------+----------+

Var. islandicus, SABINE.

ICELAND GERFALCON.

Accipiter falco islandicus, BRISS. Orn. I, 336, 1763. Falco islandicus, SAB. Linn. Trans. XII, 528, 1818.—TEMM. Man. Orn. pt. x; 17, pt. iii, p. 9; Tab. Meth. p. 2, 1836.—FABER, Prod. Island. Orn. 1822, p. 2; Isis, 1827, 62.—RICH. & SWAINS. F. B. A. II, 27, 1831.—HOY, Mag. Nat. Hist. Ser. 1, VI, 107.—HANCOCK, Ann. Nat. Hist. II, 247; Rev. Zoöl. 1839, 123.—BONAP. Consp. Av. p. 24.—STRICKL. Orn. Syn. I, 77, 1855.—CASSIN, Birds N. Am. 1858, 13. Hierofalco islandicus, GRAY, Gen. B. p. 3 (ed. 2, p. 4), 1844; Hand List, I, 18, 1869. Falco candicans islandicus, SCHLEG. Krit. übers, p. 1, 1844. Falco lanarius, FABER, Isis, 1827, 68. Falco gyrfalco, KEYSERLING & BLASIUS, Wirbelth. Eur. p. 135, 1840.

SP. CHAR. Adult (♂, Iceland; No. 12, Coll. Geo. N. Lawrence). Ground-color of the plumage dull white, gradually becoming somewhat bluish posteriorly, this color especially noticeable on the tail. Whole upper parts crossed with broad transverse bands of dark plumbeous, these bands continuous, and more than twice as wide as the pale ones, except on the upper tail-coverts and tail, where the bands of the two colors are more regularly defined and about equal; in addition to the transverse bands, the feathers anteriorly have narrow borders of white. Tail with the dark bands twelve in number; the terminal pale band is purer white than the others. The dusky plumbeous prevails on the primaries, and is unvariegated beyond the middle portion; the anterior half, however, is marked with quadrate ragged spots, of a slightly yellowish-white; all are margined terminally with purer white. Each feather of the head and neck with a narrow medial streak of dusky, but the general aspect abruptly lighter than the back; the streaks are more condensed along the upper and terminal portion of the ear-coverts. Jugulum and breast with a medial narrow streak on each feather; abdomen with more elliptical streaks; sides with circular and cordate spots, and flanks and tibiæ with transverse spots; lower tail-coverts with narrow shaft-streaks of dusky. Lining of the wing with sparse narrow streaks of dusky; under surface of primaries with white prevailing, this, however, crossed by narrow bars of dusky, these numbering about sixteen on the longest. Wing-formula, 2–3–1. Wing, 14.60; tail, 7.80; culmen, 1.00; tarsus, 2.30; middle toe, 2.00.