38 DISPOSITION TO SECURE A TERRITORY 



to a hurried return could be imagined ? It must 

 be admitted that there are certain facts which 

 might be used in support of an appeal to 

 experience as a reasonable explanation. For 

 example, the first males to arrive often display 

 that richness of colouring which is generally 

 supposed to indicate a fuller maturity. Gatke 

 even speaks of the "most handsome old birds 

 being invariably the first to hasten back to their 

 old homes." But if experience is a factor, if 

 some dim recollection of the past is held to 

 explain the hurried departure of the male 

 migrant, one wants to know with what such 

 recollection is associated. Is it associated with 

 the former female, or with the former breeding 

 place, or with both ? I take it that any recol- 

 lection, no matter how vague, must be primarily 

 associated with the particular place wherein 

 reproduction had previously been accomplished ; 

 and I grant that if the first individuals to 

 appear were invariably the older and experienced 

 birds, their early return might be explained on 

 the basis of such an association. But if there 

 is reason to believe that a proportion are young 

 birds on the verge of carrying out their instinc- 

 tive routine for the first time, then we cannot 

 appeal to past experience in explanation of their 

 behaviour. 



The age of a bird is difficult to determine. 

 Experience leads me to believe that some of 

 the males that arrive before the females are 

 birds born the previous season ; one finds, for 

 instance, individuals with plumage of a duller hue, 



