26 THE TUNDRA AND ITS FAUNA 
agony of the last march of de Long and his companions 
after the wreck of the Jeannette, it was by the help of 
the ptarmigan and reindeer shot that the final cata- 
strophe was postponed so long. After Nansen and his 
companions arrived in safety at the east coast of 
Greenland, their crossing of the inland ice completed, 
they whiled away their months of waiting for a ship by 
the help of ptarmigan shooting. Sverdrup and his 
companions shot many for food during their Arctic 
expedition, and similarly almost every expedition which 
has landed in tundra regions has noted the presence 
and characters of the birds. 
The ptarmigan share with the Arctic fox, the stoat 
or ermine, and not a few other northern forms the 
peculiarity of displaying a seasonal change of colour. 
This change doubtless aids these varied animals in 
escaping from their enemies, or in stealing unperceived 
upon their prey. Like many other tundra animals also, 
the ptarmigan is social, being found in flocks, except 
at the pairing season. This is no doubt associated with 
the fact that food is only obtainable in certain areas, 
separated by extensive barren regions. Though in most 
favourable tundra regions ptarmigan are to be found 
throughout the year, a certain amount of migration 
occurs. Thus in Greenland they are commoner in the 
south in winter than in summer. Needless to say, 
ptarmigan are not peculiar to the tundra, for they 
extend far to the south of the region. 
The only songster of the tundra is the snow-bunting 
(Plectrophenax nivalis), which is very widely distributed, 
and is spoken of by most explorers, who welcome its 
twittering song in spring. There is no doubt that it is 
largely a migrant, nesting in the north, and turning 
southwards in the autumn. Occasionally, however, 
