24 BIEDS OF. IVIGTUT. 



Greenland, and have thus had an opportunity to decide with 

 tolerable certainty to which of the species they belonged. 

 The distinguishing characteristics adopted by Mr. Ridgway 

 in his Manual cannot, in my opinion, be considered reliable. 

 One specimen, which by its general color was certainly of 

 the white form, had the under tail-coverts slightly marked 

 by dusky spots, and this specimen, as well as about half the 

 other white Falcons, had dark spots on their thighs, while an 

 occasional bird had almost as dark color on the thighs and 

 ventral region as F. rusticolus. As HolboU and Fencker 

 repeatedly observed mated pairs, one of which was white 

 (^F. islandicus'), and the other dark (^F. rusticolus'), and as 

 HolboU also found light and dark colored young in the same 

 nest, I conclude with these observers that there is but one 

 species of Gyrfalcon found in Greenland ; that the light- 

 colored birds breed chiefly in North Greenland, while the 

 dark birds are chiefly restricted to South Greenland ; and, 

 further, I believe that the two forms are related much in 

 the same way as those of the Fulmarice, some forms of 

 Stercorarius, and the mammalian Canus lagopus. I have in 

 my possession the skins of two white female Gyrfalcons shot, 

 during the breeding-season in April and May at Fredericks- 

 haab, in South Greenland. 



Besides, it seems to me unfortunate that these forms 

 should be ranked as species merely on the strength of data 

 furnished by dried skins, without taking the habits and 

 other characteristics of the living birds into consideration. 

 Especially do Mr. HolboU's observatibns seem to me valu- 

 able in settling this question. 



The following table exhibits the result of my observations 

 of the Gyrfalcon during my stay in Greenland. It is divided 

 into three columns, the first giving the number of white 

 birds observed, the second the number of those whose color 



