238 MIGRA TION. 



simply to find suitable food. The question naturally arises, 

 since all varieties of bird-food abound in the south, why 

 should a berry, a grain, a seed, or a caterpillar, be so much 

 more palatable in the north ? Nor are our regular migrants 

 generally driven back from the north by hunger and cold. 

 Nearly all our migratory birds leave for the south either 

 during the fine and fruitful days of late summer, or in the 

 most brilliant and balmy days of autumn, when they are 

 w^ell covered with an extra coat of fat, and give forth a 

 pleasing repetition of the gladsome lays of spring; and in 

 most cases they evidently go much further than is neces- 

 sary to find food and mild weather. In the gala-days of 

 spring when most birds make their passage, the weather 

 and resources of food are such that the whole journey is 

 one continuous festivity. 



Mr. Wallace admits that " the most striking fact in favor 

 of the 'instinct' of migration is the 'agitation,' or excite- 

 ment, of confined birds at the time when their wild com- 

 panions are migrating," but thinks this " a social excitement 

 due to the anxious cries of the migrating birds." No doubt 

 the tame bird may be affected by the cry of its fellow, but 

 those not within the reach of such cry, nor even within 

 sight of their passing relatives, seem equally excited in the 

 time of regular migration, spending the whole night in use- 

 less efforts to free themselves. Moreover, how came these 

 birds in confinement, these life-long prisoners shut out from 

 the society of their kind, to recognize each the call of its 

 fellows, and to comprehend its meaning? Again, the same 

 writer says: "We must remember, too, that migration, at 

 the proper time, is in many cases absolutely essential to the 

 existence of the species; and it is therefore not improbable 

 that some strong, social emotion should have been gradu- 

 ally developed in the race, by the circumstance that all 



