180 The Migration of Birds 



were, it seems more than likely that the long arctic 

 night, when for three months the sun does not rise 

 above the horizon, alone would have taught the birds 

 to migrate at least a few hundred miles north and 

 south. These theories have an interest, and as we 

 ponder over them we may get some light upon the 

 subject; but let us remember to state them as theories, 

 much as we should like to prove or disprove them. 



Some theorists, without attempting to see so far 

 back into the early conditions causing the great an- 

 nual pilgrimage of our birds, argue that the desire for 

 a genial climate, where food is plentiful, can alone 

 account for this great phenomenon. Another theory, 

 urged by many, is that the annual nesting season is 

 sufficient to cause migration. The believers of this 

 argue largely from the conditions existing to-day. 

 Birds, and in fact most animals, have an innate desire 

 for seclusion during the period of reproduction, and 

 will seek some retired locality in which to bring forth 

 their young. This pertains not only to those birds 

 which winter in South America and nest in Canada, 

 for tropical birds also will seek secluded places 

 within their own zone; and the seclusion habit con- 

 cerning the eggs and young is very noticeable in our 

 turkeys and Guinea fowl as well. Among the fish, the 

 salmon is most noted for its long journey from the 



