MARSH WARBLER 



feature may quite well escape our attention, a feature so small 

 perhaps as to be beyond our powers of observation, but never- 

 theless sufficiently great to suggest a different meaning to the 

 more delicate perceptual powers of a bird. We must, there- 

 fore, make due allowance for our own imperfections in this 

 respect. Professor Lloyd Morgan suggests to me that the 

 motor reactions may be only generically similar, that even 

 they, as such, may very likely be specifically differentiated, 

 and that the total complex of the emotional situation, involv- 

 ing factors so many and so varied, may be yet more markedly 

 and distinctly differentiated. He sees no reason why a generic 

 motor expression, supplemented by allied organic sensations, 

 and qualified in experience by the total meaning of adaptive 

 behaviour, should not be differentiated in different situations — ■ 

 the mating situation and the fighting situation — so as to bear 

 its part with a difference in both. This of course is quite 

 possible, but unsafe as it may therefore be to speak of specific 

 similarity, I am nevertheless inclined to think that I have 

 observed it on more than one occasion and in more than one 

 situation. The emotional behaviour is most intense during 

 sexual activity and while the young require the care and 

 attention of their parents. The intermediate time is occupied 

 almost wholly by incubation, and though this is a time of 

 comparative quietude, yet even then there are frequent ex- 

 hibitions of a similar behaviour, which, however, never 

 reach a similar degree of intensity. Such exhibitions may 

 occur at the assemblies of the males, when a territory is 

 intruded upon by a neighbouring individual of the same or 

 another species, or when a Cuckoo or some predatory bird 

 approaches the locality in which the nest is situated. But 

 for our present purpose we may disregard the minor exhibitions 

 and compare those two in which the motor reactions are 

 observed to be most in evidence. In the life-history of the 

 Lesser Whitethroat this similarity has already been touched 

 upon. I there stated that both the Whitethroat and Lesser 

 Whitethroat, when anxious about their young, behaved in a 



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