THE GLACIAL RANGE CONTRACTION, ETC. 67 



termination during the Glacial Epoch. Very different, 

 however, was the case of the Arctic birds that lived 

 on animal substances alone — the Plovers, Sandpipers, 

 and their allies. The range of these species at the 

 coming on of the Ice Age became more and more 

 southerly, and their migrations inter-polar, probably 

 because they could not find suitable winter quarters 

 or breeding grounds except in the Polar regions. 

 As I have already shown in the Jlligj'ation of Birds, 

 we have abundant proof of this Inter-polar Migra- 

 tion and Emigration, not only in the vast journeys 

 many of these birds still undertake, but in the many 

 allied forms left behind in the Southern Hemisphere 

 when the northern Glacial Epoch passed away and 

 the North Polar breeding grounds became available once 

 more. It is a most significant fact that every Chara- 

 driinee species goes further south to winter than our 

 first Refuge Area ; that is to say, that although some 

 members of certain species may winter therein, other 

 members extend their flight to the south of it. Not a 

 single species of the Charadriidse can be classed as a 

 Nomadic Migrant. Not a single migratory species (non- 

 Nomadic) throiiglioiit the NortJiern Heuiisphe^'e ivifiters 

 exclusively ^vitJlin what are defined by uncontrovertible 

 evidence to he tJie limits of glaciation — eloquent testimony, 

 I take it, of the southern range bases during Pleistocene 

 time of all the surviving species that have now re-peopled 

 the once glaciated land areas. To my mind these facts 

 are convincing proofs that the high Polar latitudes were 

 deserted by bird-life ages before it was exterminated 

 from more temperate and southern latitudes ; in other 



