REED WARBLER 



efforts to obtain the food. We may then almost say that the 

 whole process is a mechanical one ; the parents know not, 

 neither could they possibly recognise that one individual is 

 stronger and thus would demand more food than another, still 

 less could they possibly comprehend the difference being a 

 sexual one, if indeed it were so. Their behaviour is solely 

 determined by the organic response of the young. It is not 

 necessary for them to consider — nor do I believe that they 

 would be capable of doing so — a matter so abstruse as supplying 

 food in rotation; it is not even necessary for them to remember 

 to which individual they delivered the last supply of food, 

 although it is not improbable that they sometimes do so. 

 After watching the routine of different pairs under similar 

 conditions, I can see no reason to believe that they in any 

 way profit by experience. How far their whole behaviour 

 may be congenital, or how far traditional, it is difficult to say. 

 We cannot assume that a young male and a young female 

 never mate together, for if we consider the proportion of young 

 birds to old, we can see that cases must frequently arise in 

 which a pair are compelled to build a nest and rear young- 

 antecedent to experience. In some of the cases which I have 

 from time to time studied, there is a strong probability that 

 the actors have been performing for the first time ; and, if so, 

 they have taken their part in this complex piece of machinery 

 as skilfully as the adults. It is true that we could place their 

 whole behaviour on a level with our own; we could discern 

 a motive in their supplying one individual more than another 

 with food, could regard the removal of the faaces as an act 

 of conscious deliberation, could indeed see all their actions in 

 the highest light possible and thus attribute to them reasoning 

 powers similar to our own ; but of what use would such a 

 method be ? Conclusions thus reached would retard rather 

 than facilitate our knowledge of their subjective states, and it 

 might truthfully be said that they would never even enter the 

 domain of science. 



I have in the case of this species also carried out a series 



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