144 THE STORY OF THE BIRDS 



devote a chapter not only to the various in- 

 fluences which may be said to govern this dis- 

 persal of avine life over the globe as fixed and 

 sedentary colonists, but as transitory visitors 

 to certain areas, which are reached by what 

 we term migration. The laws governing the 

 Dispersal and Migration of birds are as yet 

 but very little understood, and so long as 

 naturalists believe that these facts are chiefly 

 due to fortuitous agency, and are controlled 

 by accidental circumstances, our knowledge is 

 likely to remain very small, and our concep- 

 tion of the phenomena to be quite erroneous. 

 It must also be understood that the Dispersal 

 of birds and the Migration of birds are two 

 very intimately related subjects ; we cannot 

 discuss or study one without the other ; for as 

 we have already repeatedly insisted, they are 

 really correlative parts of the same phenomenon, 

 the Dispersal of birds being the key by means 

 of which we are enabled to solve not a few of 

 the mysteries of Migration. 



We will first then devote a few pages to the 

 Dispersal of birds. How many readers might 

 reasonably conclude that Birds, of all living 

 things, would be the least likely to be confined 

 to certain areas, and especially to restricted 



