54 THE BOOK OF MIGRATORY BIRDS 



Britannica" rejects the idea of instinct as a mere evasion 

 of the difficulty of the question, and as excluding all 

 scientific investigation of the same. According to his 

 view, birds act unconsciously in a manner suited to a 

 certain purpose; but what, one might ask, is this but 

 instinct? 



The absorbingly interesting subject of bird migration 

 is one that cannot be dealt with in a few cursory notes, or 

 in any wise scantily treated, for whatever theory is 

 advanced the idea baffles the most devoted student of 

 natural history. 



An excellent authority very ably puts it thus and this 

 view is the one now generally adopted on this question : 

 "Originally birds lived in latitudes which supplied 

 them throughout the whole year with everything neces- 

 sary to their existence ; that in progress of time some 

 of them accidentally came to stray so far beyond the 

 northern limit of their home that on the approach of 

 winter they were compelled to retrace their path thither 

 in order not to succumb to cold and hunger : that a 

 habit of migration was developed from such accidental 

 erratic wanderings, and that this habit, together with 

 the experiences made on these journeys, had been passed 

 on by inheritance from the old birds to their young." 

 He further states that the flock of migrants generally 

 had for their leaders older and stronger individuals : that 

 the young were not possessed of an inborn consciousness 

 of the necessity of migration, but had to learn all this from 

 their parents. 



The roads frequently travelled over by these old birds 

 consisted of a succession of spots favourable for taking 

 rest; or feeding grounds on which they were dependent, 

 and the so-called routes of migration were determined by 

 the geographical situation of such places. Such young 

 birds again, as travel alone, are further credited with the 

 possession of a so-called local sense or local memory. 

 This is acquired at first by their getting to know such 

 feeding-grounds as are situated in the immediate vicinity 



