40 DISPOSITION TO SECURE A TERRITORY 



next year by the song of the rarer Marsh- 

 Warbler also ; and so on. The fluctuation is 

 considerable : we observe desertion on the one 

 hand, appropriation on the other, and yet males 

 appear before females whether the particular 

 plantation, osier bed, or swamp had been in- 

 habited or not the previous season. This fact is 

 not without significance. It shows that similar 

 conditions prevail both amongst the males that 

 appropriate breeding grounds new to them, and 

 amongst those that return to some well- 

 established haunt ; and on the assumption that 

 the earlier arrivals are experienced males, the 

 same birds evidently do not return to the same 

 place year after year. Granting, then, that the 

 males which appropriate new breeding-grounds 

 are young birds, how can their earlier arrival 

 be explained in terms of past experience ; and 

 granting that they are old, and therefore 

 experienced, how can it be explained in terms of 

 association ? 



Again, it may be urged that if there is some 

 biological end to be furthered by this hurried 

 return, and if recollection of past experience is a 

 means towards that end, such recollection need 

 not necessarily be associated with a definite 

 place, but only in a vague way with the whole 

 series of events leading up to reproduction in 

 which series the migratory journey may even 

 have acquired meaning. Whether there be any 

 recollection of a previous journey or of a nest 

 with young, I do not know. But the young 

 bird is capable of performing its journey, of 



