THE GYR-FALCONS. 



193 



land Gyr-Falcon can be told, at any age, by its yellow bill, and 

 by never having bars on the flanks. If a specimen comes from 

 Greenland with a blue bill and with cross-bars on the flanks, 

 it is not a Greenland Gyr-Falcon, but Holboell's Gyr-Falcon 

 (Hierofalco holboelli}. All the Grey Gyr-Falcons, of which H, 

 holboelli is a light arctic race, have blue bills and barred flanks. 

 The above characters at once separate the Greenland Gyr 

 Falcon from the Grey Gyr-Falcons, H. gyrfalco and its allies, 

 of which H. holboelli is one. 



The young H. candicans is a streaked bird with longitudinal 

 brown streaks on the flanks. Of this there can be no doubt : 

 but many white birds are often transversely barred with black| 

 while others are white, with longitudinal broad streaks in the 

 process of breaking up into cross-bars or spots. This plumage 

 I believe to be indicative of a change of pattern in the feather, 

 which is effected without any moult. There is nothing wonderful 

 in this theory, for many Hawks and other birds change their 

 colour without shedding a feather. The barred specimens 

 may be birds of the second year, or females, which always 

 take longer to assume adult plumage than the males, or they 

 may even be due to hybridisation with Holboell's Gyr-Falcon, 

 though I never like to adopt this last " refuge for the destitute," 

 in the case of changes of plumage which we do not exactly 

 understand. My conclusions have been derived from speci- 

 mens shot in a wild state, and I decline to be influenced by 

 observations made from these Gyr-Falcons in confinement, for 

 a snowy-white bird like the present species would assuredly be 

 influenced by confinement in a smoke-laden atmosphere like 

 that of England, away from its arctic surroundings, and de- 

 pending on the strength necessary to perform its normal func- 

 tions of moulting on the food supplied to it in a menagerie. 



Range in Great Britain. An accidental visitor, occurring dur- 

 ing the autumn and winter migrations. Although it has been 

 recorded at intervals in various counties of England, most of 

 the specimens have been procured in Ireland and Scotland, as 

 might have been expected in a wanderer from the north. 



Range outside the British Islands. The Greenland Gyr-Falcon 

 is a typical arctic species, and only occurs within European 

 limits during the autumn and winter, when a few individuals, 

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