COMMON PTARMIGAN 
seasons in which they occur, but the individual variation in this species 
being almost as great as in the red grouse, it has been found impossible 
to give more than a general description. It must also be borne in 
mind that the plumage of every individual is constantly changing month 
by month, either by moult, or by the wearing off of the light tips of the 
feathers; likewise that the changes in plumage are greatly influenced 
by the mildness or severity of the climate in which the birds are found. 
For instance, the majority of the ptarmigan inhabiting Scotland are only 
to be seen in complete white plumage in exceptionally severe winters, 
and usually retain a good many of the old summer- and autumn-feathers 
on the top of the head and back; while male birds from the northern 
parts of Scandinavia, etc., never complete either their summer- or 
autumn- plumage, but retain a large amount of white plumage through- 
out the year. 
These irregularities in attaining the full seasonal plumages are no 
doubt protective, and help to render the birds less visible when 
crouching among the stones and rocks and hiding from their many 
enemies. 
General distribution . — The ptarmigan makes its home among the high 
stony table-lands and rocks above the limits of tree-growth and heather. 
The exact eastern limits of its range are somewhat difficult to define, 
but the typical form with a grey autumn -plumage inhabits the mountains 
of Europe, while that met with in some of the ranges of Central Asia 
should be referred to the more northern rufous form (Lagopus rupestris)^ 
which was the bird found by Seebohm on the Yenesei at 71|° N. latitude. 
In the west it ranges to the mountains of Scotland, the Lofoden Islands, 
Scandinavia and Finland, and in the north to the Kola Peninsula and Ural 
Mountains. Southwards it is met with in the higher parts of the Pyrenees, 
and is said to occur in the mountains of Asturias and Leon. It is also 
found in the Alps, Tyrol, Styria and Carinthia. Its eastern range, as 
already stated, is difficult to define, owing to lack of material. 
Allied forms . — In Greenland, Iceland, Northern, Central, and Eastern 
Asia, and in Japan, its place is taken by a closely allied form (L. rupestris), 
which has a more rufous -brown plumage in summer and autumn, all 
the forms being, of course, indistinguishable in their white winter-dress. 
From the Aleutian Chain, Alaska and Arctic America numerous forms 
have been described under different names, and from the mountains of 
Newfoundland a grey form, very similar to the typical European bird, 
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