THE RYR-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 bhte 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 If. holboelli is one. 
The young //. 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. 
Eange in Great Britain.— An accidental visitor, occurring dur- 
ing the autumn and winter migrations. Although it has been 
reeorded 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. 
Eange 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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