68 THE MIGRATION OF BRITISH BIRDS 



words, that the various climatic fluctuations of the Ice 

 Age waxed and waned very slowly. It should be re- 

 marked that the range of some of the species tabulated 

 may be lower in the New World than in Europe, due 

 to more rigorous climatal conditions and to the much 

 greater southern extension of the glaciers in North 

 America. 



It requires but little strain upon the imagination to 

 recall the avian characteristics of this Refuge Area I. 

 at the climax of the third cold period of the Ice Age. 

 England south of Yorkshire, the Bristol Channel, and 

 much of the land now lying submerged beneath the 

 English Channel and the North Sea, were probably 

 in the condition of an Arctic tundra, bounded by the 

 sea on the south in which huge icebergs floated, and 

 on the north by the vast glacier whose southernmost 

 slopes retreated or advanced a little way as summer or 

 winter came on. The resident land birds were few in 

 number. The Twite and the Mealy Redpole wandered 

 about the winter wastes subsisting on the seeds that 

 were obtainable amongst the snow ; the charming little 

 Snow Buntings gathered into flocks and led the nomad 

 life they still continue to lead, going no further south 

 than their very limited range base extended, hurrying 

 north again with the first dawn of spring. The Willow 

 Grouse, clad in its winter plumage of unsullied white, 

 managed to find enough food in the buds and seeds 

 and twigs, and in the frozen Arctic ground fruits which 

 it managed to obtain by burrowing into the snow. The 

 large Arctic Falcons and the Snowy Owl kept closely 

 to the tundras and the shores, preying upon the h'inches 



