that but a single pair remained, the young disappearing in the course of the season.
Sir John Richardson, in his Arctic expedition in 1845, while descending the Mackenzie River, latitude 65°, noticed what he presumed to be a nest of this species, placed on the cliff of a sandstone rock. This Falcon was rare on that river.
Mr. MacFarlane found this species not uncommon on the banks of Lockhart and Anderson Rivers, in the Arctic regions. In one instance he mentions finding a nest on a cliff thirty feet from the ground. There were four eggs lying on a ledge of the shale of which the cliff was composed. Both parents were present, and kept up a continued screaming, though at too great a distance for him to shoot either. He adds that this bird is by no means scarce on Lockhart River, and he was informed that it also nests along the ramparts and other steep banks of the Upper Anderson, though he has not been able to learn that it has been found north of Fort Anderson. In another instance the nest was on a ledge of clayey mud,—the eggs, in fact, lying on the bare ground, and nothing resembling a nest to be seen. A third nest was found on a ledge of crumbling shale, along the banks of the Anderson River, near the outlet of the Lockhart. This Hawk, he remarks, so far as he was able to observe, constructs no nest whatever. At least, on the Anderson River, where he found it tolerably abundant, it was found to invariably lay its eggs on a ledge of rock or shale, without making use of any accessory lining or protection, always availing itself of the most inaccessible ledges. He was of the opinion that they do not breed to the northward of the 68th parallel. They were also to be found nesting in occasional pairs along the lime and sandstone banks of the Mackenzie, where early in August, for several successive years, he noticed the young of the season fully fledged, though still attended by the parent birds.
In subsequent notes, Mr. MacFarlane repeats his observations that this species constructs no nest, merely laying its eggs on a ledge of shale or other rock. Both parents were invariably seen about the spot. In some instances the eggs found were much larger than in others.
Mr. Dall mentions shooting a pair near Nuk´koh, on the Yukon River, that had a nest on a dead spruce. The young, on the 1st of June, were nearly ready to fly. It was not a common species, but was found from Nulato to Sitka and Kodiak.
In regard to general characteristics of this Falcon, they do not apparently differ in any essential respects from those of the better-known Falco communis of the Old World. It flies with immense rapidity, rarely sails in the manner of other Hawks, and then only for brief periods and when disappointed in some attempt upon its prey. In such cases, Mr. Audubon states, it merely rises in a broad spiral circuit, in order to reconnoitre a space below. It then flies swiftly off in quest of plunder. These flights are made in the manner of the Wild Pigeon. When it perceives its object, it increases the flappings of its wings, and pursues its victim with a surprising rapidity. It turns, and winds, and follows every change of motion of the object of pursuit with instantaneous quickness. Occasionally it seizes a bird too heavy to be managed, and if this be over the water it drops it, if the distance to land be too great, and flies off in pursuit of another. Mr. Audubon has known one of this species to come at the report of a gun, and carry off a Teal not thirty steps distant from the sportsman who had killed it. This daring conduct is a characteristic trait.
This bird is noted for its predatory attacks upon water-fowl, but it does not confine itself to such prey. In the interior, Richardson states that it preys upon the Wild Pigeon, and upon smaller birds. In one instance Audubon has known one to follow a tame Pigeon to its house, entering it at one hole and instantly flying out at the other. The same writer states that he has seen this bird feeding on dead fish that had floated to the banks of the Mississippi. Occasionally it alights on the dead branch of a tree in the neighborhood of marshy ground, and watches, apparently surveying, piece by piece, every portion of the territory. As soon as it perceives a suitable victim, it darts upon it like an arrow. While feeding, it is said to be very cleanly, tearing the flesh, after removing the feathers, into small pieces, and swallowing them one by one.
The European species, as is well known, was once largely trained for the chase, and even to this day is occasionally used for this purpose; its docility in confinement, and its wonderful powers of flight, rendering it an efficient assistant to the huntsman. We have no reason to doubt that our own bird might be made equally serviceable.
Excepting during the breeding-season, it is a solitary bird. It mates early in February, and even earlier in the winter. Early in the fall the families separate, and each bird seems to keep to itself until the period of reproduction returns.
In confinement, birds of this family become quite tame, can be trained to habits of wonderful docility and obedience, and evince even an affection for the one who cares for their wants.
This species appears to nest almost exclusively on cliffs, and rarely, if ever, to make any nests in other situations. In a few rare and exceptional cases this Falcon has been known to construct a nest in trees. Mr. Ord speaks of its thus nesting among the cedar swamps of New Jersey; but this fact has been discredited, and there has been no recent evidence of its thus breeding in that State. Mr. Dall found its nest in a tree in Alaska, but makes no mention of its peculiarities.
The eggs of this species are of a rounded-oval shape, and range from 2.00 to 2.22 inches in length, and from 1.60 to 1.90 in width. Five eggs, from Anderson River, have an average size of 2.09 by 1.65 inches. An egg from Mount Tom, Mass., is larger than any other I have seen, measuring 2.22 inches in length by 1.70 in breadth, and differs in the brighter coloring and a larger proportion of red in its markings. The ground is a deep cream-color, but is rarely visible, being generally so entirely overlaid by markings as nowhere to appear. In many the ground-color appears to have a reddish tinge, probably due to the brown markings which so nearly conceal it. In others, nothing appears but a deep coating of dark ferruginous or chocolate-brown, not homogeneous, but of varying depth of coloring, and here and there deepening into almost blackness. In one egg, from Anderson River, the cream-colored ground is very apparent, and only sparingly marked with blotches of a light brown, with a shading of bronze. An egg from the cabinet of Mr. Dickinson, of Springfield, taken on Mount Tom, Massachusetts, is boldly blotched with markings of a bright chestnut-brown, varying greatly in its shadings.
Æsalon, Kaup, 1829. (Type, Falco æsalon, Gmelin, = F. lithofalco, Gm.)
Hypotriorchis, Auct. nec Boie, 1826, the type of which is Falco subbuteo, Linn.
Dendrofalco, Gray, 1840. (Type, F. æsalon, Gmel.)
This subgenus contains, apparently, but the single species F. lithofalco, which is found nearly throughout the Northern Hemisphere, and in different climatic regions is modified into geographical races. Of these, North America possesses three, and Europe one; they may be distinguished as follows:—
F. lithofalco. Second and third quills longest; first usually shorter than, occasionally equal to, or rarely longer than, the fourth. Adult female, and young of both sexes. Above brownish, varying from pale earth-brown, or umber, to nearly black, plain, or with obscure transverse spotting of lighter; tail with five to eight lighter bands, which, however, are sometimes obsolete, except the terminal one. Beneath ochraceous-white, longitudinally striped with brown or dusky over the whole surface. Adult male (except in var. suckleyi and richardsoni?). Above plumbeous-blue, with darker shaft-streaks; tail with more or less distinct bands of black, and paler tip. Beneath much as in the female and young, but stripes usually narrower and more reddish. Wing, 7.20–9.00; tail, 4.90–6.30; culmen, .45–.60; tarsus, 1.30–1.60; middle toe, 1.15–1.51.
a. Adult male plumbeous-blue above; sexes very unlike in adult dress. Female and young without transverse spotting on upper parts.
Adult male. Tail deep plumbeous, tipped with ash, with six transverse series of dusky spots (which do not touch the shaft nor edge of the feathers)
