THE MIGRATION OF BIRDS 



Deeper Problems of Migration? 



It is interesting to inquire where we should rank 

 migration on the inclined plane of animal activities, 

 but no secure answer can be given in the present 

 state of science. It seems to partake very largely 

 of the nature of instinct, that is to say, birds have 

 a specific hereditary preparedness or disposition for 

 their migratory movements, which enables them to 

 go through with them without education or experi- 

 ence. But this does not exclude the view that birds 

 have their wits about them as they fly, for many 

 instinctive activities show a spice of intelligence. 

 Nor does it exclude the view that birds migrate 

 more successfully as they grow older, for instinctive 

 routine may be intelligently perfected by practice. 

 That the migratory activity has an instinctive basis 

 is suggested by its regularity and orderliness, with- 

 out much individuality and with little hint of 

 caprice ; and by the preparations made before there 

 is any real need. Moreover it must be remembered 

 that none of our summer visitors have any personal 

 experience of wintry conditions, literally knowing 

 no winter in their year. The idea of instinctive or 

 inborn predisposition and capacity is also suggested 

 by the success with which many young birds carry 

 it through, apparently unguided and untutored ; 

 by a few observations of the restlessness shown at 

 the proper time by comfortably caged migrants ; 

 and by the occurrence of other true migrations in 

 widely separated divisions of the animal kingdom. 

 Periodic movements occur in many other creatures 

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