INTERNAL MIGRATIONS. 



53 



in the temperate regions of the Southern Hemisphere 

 are birds banished by the South Polar Glacial 

 Epoch ; many of them are sedentary on the 

 mountains ; others have acquired regular habits of 

 vertical migration, just as we have seen is the case 

 with many species in the Northern Hemisphere. 



We thus see that the study of Migration in the 

 Southern Hemisphere is a very important one, for it 

 enables us to test the soundness of the views we 

 have expressed, and tends to confirm them in no 

 uncertain way. When migration has been studied 

 in this part of the world as diligently as in the 

 Northern Hemisphere, and we have consequently the 

 same abundance of material from which to make 

 deductions concerning it, the nature and purpose 

 of this grand and important avian movement in 

 the Antipodes will not be found to differ in any 

 important respect from that prevailing in the 

 opposite hemisphere. 



We now pass to the second pordon of the 

 subject of the present chapter, the Local Movements 

 of Birds. These local movements are almost if 

 not entirely confined to the season of winter in the 

 temperate zones, and to the dry season in the 

 torrid zone of the earth. They are indulged in not 

 only by endemic species in each of these great 

 regions, but by migrants whilst sojourning in their 

 winter quarters. Probably the only cause of these 

 local movements, wherever they occur, is due to 

 failure of food supply. Although these movements 

 have been little studied by naturalists, especially in 



