MAESH WAEBLER 



is manifest, since they are either essential to its welfare or 

 necessary for the attainment of reproduction. Every bird 

 must search for and find sufficient food; again, every bird 

 must be in possession of a suitable territory, and most birds 

 must build a nest if incubation is to be carried out success- 

 fully, and any individual that came into the world imperfectly 

 endowed with just those qualities requisite for a proper 

 carrying out of the routine of activities, would either 

 succumb or fail in the attempt at reproduction. The life of a 

 bird is not, however, wholly spent in searching for food or in 

 making preparations for its progeny ; each species, in addition, 

 behaves at certain definite times in certain definite ways, 

 and it is this behaviour which we will now examine, 

 limiting the investigation to those species whose peculiar but 

 characteristic attitudes it is the purpose of these plates to 

 demonstrate. It would be difficult to find a family more 

 suitable for such an investigation, for, on the one hand, the 

 nervous system of its different members is so framed as to 

 produce a visible emotional behaviour seldom surpassed in 

 bird life, and, on the other, the secondary sexual characters 

 are not highly developed. The combination of these two 

 characteristics in the same individual is important; for 

 since the emotional behaviour reaches its highest degree 

 of intensity, and the secondary sexual characters their 

 greatest development during the period of reproduction, a 

 direct relation between the two has always been deemed 

 more than probable. 



The period of reproduction is the period when behaviour 

 is most emotional, and part of that period we often find referred 

 to as one of courtship. We read of "the courtship being 

 a prolonged affair," or that " courtship may thus be regarded, 

 from the physiological point of view, as a means of producing 

 the requisite amount of pairing hunger," or, again, " that 

 it is the instinctive coyness of the female that necessitates all 

 the arts of courtship," but of the term courtship no explana- 

 tion is offered. The word is indefinite, implying a period of 



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