EMIGKA TTON AND E VOL UTION. 1 1 3 



confusion between the two words Emigration and 

 Migration ; by many persons they are regarded as 

 synonymous expressions, and aj)phed indiscrimin- 

 ately to these very distinct avian movements. 

 When the term Emigration is apphed to birds, it 

 is intended to express a colonizing movement, a 

 journey with no return, or a spasmodic or gradual 

 extension of geographical area. By the term 

 Migration, a regular passage between two districts 

 or regions is implied. Emigration is either fitful 

 and irregular, or very gradual if constant ; Migration 

 is both regular, constant, and seasonal. 



The present universal distribution of Birds over 

 the earth's surface can only be accounted for in one 

 of two ways. Either we must admit that every 

 bird was created in the area which it now occupies, 

 or that birds have emigrated in endless directions 

 from centres of dispersal. The former explanation 

 demands the acceptance of the theory of Special 

 Creation, a theory that all the teachings of modern 

 science have utterly exploded, and proved to be as 

 illogical as it is false. The latter explanation, the 

 theory of Evolution, of Descent wdth Modification, 

 which implies that birds have sprung from common 

 ancestors, is completely in harmony with the facts 

 that are presented to us, not only in the present 

 distribution of animal life, but with the vast changes 

 that our globe has suffered in past ages. 



The most important causes of emigration, and 

 those which have probably had the most influence 

 on this means of dispersal, are the great climatal 



