306 



NORTH AMEUICAN BIRDS. 



liarative Zoology, Cambridge, 10; Cab. G. N. Lawrence, 6; Coll. W. S. Brewor, 3; R. 

 Ridgway, 4. Total, 85. 



Afeasuremenis. 



That all the North Ainericau Eough-legged Hawks, whether light or dark 

 (e.xcepting of course the A. fcrrugineus), are one species, aud also one race, 

 there appears to be but little doubt ; a critical comparison and minute e.x- 

 amination of about one hundred specimens also proves that the dark plu- 

 mage, usually separated as " A. sanrti-johannis" has nothing to do with age, 

 sex, season, or locality, but that, as in Bidco borcalis var. calurus and B. 

 smdtisoni, it is a purely individual condition, lilack 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 he the fact that certain regions are frequented more 

 by birds of one color than another, aud of the many hundreds of specimens 

 sent from the Arctic regions to the Smithsonian Institution by oSicers 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. IGIO, and description, 

 on p. 1624. 



Habits. The Eough-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 distribu- 

 tion of tlie American variety appears to be nearly throughout the entire 

 Union, irom 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. Buckley and Cooper. It was not seen 

 by Mr. Dresser in Texas nor by Dr. Woodhouse in New Mexico, but it was 

 taken near Zuni 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 

 neii'hborhood of Niagara Falls. In tlie 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, tlie pair thus presenting well-marked illustrations of 

 the two types, the black sanrti-johannis and the common lagoptis. 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. 



