| Sex. | Wing. | Tail. | Culmen. | Tarsus. | Middle Toe. | Specimens. |
|---|---|---|---|---|---|---|
| ♂ | 15.80–16.80 | 9.80–10.00 | .85–.90 | 2.75–2.80 | 1.35–0.00 | 18 |
| ♀ | 16.15–17.70 | 9.00–10.50 | .90–1.00 | 2.80–0.00 | 1.30–1.40 | 8 |
| 15.75–18.00 | 9.00–11.00 | .80–1.00 | 2.15–3.00 | 1.20–1.50 | 40 |
That all the North American Rough-legged Hawks, whether light or dark (excepting of course the A. ferrugineus), are one species, and also one race, there appears to be but little doubt; a critical comparison and minute examination of about one hundred specimens also proves that the dark plumage, usually separated as “A. sancti-johannis,” has nothing to do with age, sex, season, or locality, but that, as in Buteo borealis var. calurus and B. swainsoni, it is a purely individual condition, black birds being black, and light birds being light, from the first plumage till death. Each phase has its young and adult stages distinctly marked, as the above diagnoses point out. It however appears to be the fact that certain regions are frequented more by birds of one color than another, and of the many hundreds of specimens sent from the Arctic regions to the Smithsonian Institution by officers of the Hudson’s Bay Company, none exhibited the blackish plumage which, on the other hand, appears most abundant about Hudson’s Bay.
The North American birds are distinguishable from European ones (var. lagopus) by the characters given in the synopsis on p. 1619, and description, on p. 1624.
Habits. The Rough-legged Hawk of North America bears so close a resemblance to the European species, in all respects,—plumage, habits, and eggs,—that the two are generally considered to be identical. The distribution of the American variety appears to be nearly throughout the entire Union, from the Atlantic to the coast of the Pacific, and from New Mexico to the Arctic regions. It was taken at Fort Steilacoom, and at Shoal-water Bay in Washington Territory, by Drs. Suckley and Cooper. It was not seen by Mr. Dresser in Texas nor by Dr. Woodhouse in New Mexico, but it was taken near Zuñi by Dr. Kennerly, was found from Mimbres to the Rio Grande by Dr. Henry, and obtained near Fort Fillmore by Captain Pope, and at Fort Massachusetts by Dr. Peters.
The Rough-legged Hawk is quite abundant in spring and fall in the neighborhood of Niagara Falls. In the fall of 1872, Mr. James Booth met with a pair of this species, accompanied by their young. The latter were fully grown. The male bird was in very black plumage, while the female was unusually light, the pair thus presenting well-marked illustrations of the two types, the black sancti-johannis and the common lagopus. The parents were secured, and are now in the museum of the Boston Society of Natural History. One of the young was also shot, but I did not see it. It was said to have been only a little less dark plumaged than the male parent.
It is very abundant throughout the Arctic regions, where it was found breeding in the Anderson River country by Mr. MacFarlane, from whom were received valuable notes and a large number of specimens of birds and eggs. It was observed generally by Dr. Richardson’s party, but owing to its extreme wariness only a single specimen was obtained. Richardson noted its arrival in the fur countries in April or May, and gives the time of its departure as early in October.
Dr. Kennerly mentions finding this Hawk quite abundant in the vicinity of the Pueblo Zuñi, where it confined itself in the neighborhood of the stream, watching eagerly for ducks, which seemed to be its favorite prey.
Archibuteo lagopus (Europe).
Dr. Cooper found a large number of these Buzzards on a low point near the sea-coasts, at Shoalwater Bay, Washington Territory, in October. This point was covered with small pines, on the dead tops of which they were observed sitting in the manner of owls. Occasionally one would dart down after a mouse, and alight a short distance off. At times they would call to each other with a loud scream, but they usually sat motionless and silent for hours together. Some remained there throughout the winter, and he had no doubt that a few build near the mouth of the Columbia, where he saw young birds in July. In California, the same writer states, this species is only a winter visitor, and has never been observed by him south of Santa Clara Valley.