(Subgenus Hierofalco) form a striking group of large, closely allied Falcons, in which the middle toe is shorter than the tarsus, which is densely feathered in front and on the sides for the upper two thirds. A further mark of distinction is found in the fact that only a single quill (the outermost) has the web emarginated. Of these birds we may first mention the White Gyrfalcon (F. islandus), a bird about twenty-three inches long, which is found exclusively in the circumpolar regions. The adult is mainly white, but with the head and hind neck often narrowly streaked with dusky, and the upper parts more or less barred or transversely spotted with slate-dusky. It is an extremely shy bird, and when sitting with its pure white breast toward the intruder will often escape detection on the snow. It flies well, with rapid beats of the wings, followed by a short sail, and frequents rocky coasts where great numbers of water fowl are nesting, feeding largely upon them, as well as upon Ptarmigan and other birds. Our knowledge is at present rather limited as to its nesting habits, but so far as known the nest is usually placed on a rocky ledge. It was found by the Polaris Arctic Expedition near Cape Hays in latitude 79° 44 north, where it was breeding on cliffs. The Gray Gyrfalcon (F. rusticolus) is a bird of the extreme northern portions of Europe, Asia, and North America, including Iceland and southern Greenland. It is slightly smaller than the last, and, while light colored, has the upper parts everywhere more or less distinctly barred with bluish gray and dusky. Its habits are similar to those of the white species, and similarly it nests on inaccessible cliffs along the seashore. The eggs are said to be three or four in number and creamy white, spotted and blotched with reddish brown.
Closely allied is the Gyrfalcon (F. rusticolus gyrfalco) of northern Europe and Arctic America from northern Labrador and the coasts of Hudson Bay to Alaska. It is a slightly darker bird than the last, while the Black Gyrfalcon (F. r. obsoletus) of Labrador is still darker. In winter this bird comes south to Canada, Maine, and New York, but it is common only in its northern home. Like the other forms mentioned this one also nests on high cliffs, the following description of a nest being from the pen of Mr. L. M. Turner, who, found them nesting on the Chapel, an immense rock three hundred feet high with precipitous and nearly inaccessible sides, near Fort Chimo, Ungava. He says: “I went with a party of four to lower me over the cliff to secure the eggs which might remain in the nest. I descended to the nest. In front of it huge icicles stood joined with the slightly projecting roof above the ledge; some of these ice columns were two or three inches thick and four inches wide, forming an icy palisade around the edge of the nest and permitting approach to the interior only by a narrow space or doorway next the main wall of rock, and I was compelled to detach the ice before I could reach the four eggs I saw within the nest, which was composed of a few twigs and branches of larch and spruce, irregularly disposed on the outer side of the rim of the nest to prevent the eggs from rolling out, forming only a semicircular protection, while the rear portion was a part of the bare rock of the ledge. Below these twigs were the remains of former nests.”