GENERAL SUMMARY AND CONCLUDING REMARKS 



as Professor Groos says in referring to a similar habit of the 

 Wren, is only one step further in the same direction. Is 

 the habit confined to those males only which share the task 

 of constructing the nest with the female ? We must know 

 this before we can hope to reach any definite conclusion, and 

 I have not sufficient data to go upon. But if it were so, 

 Ave need hardly, one would think, regard the habit as a 

 detached and inexplicable incident in the sexual life of the 

 bird, but as a genuine step on the part of the male towards 

 building the nest. 



We come now to the actual construction of the nest. 

 Nothing in nature is perhaps more wonderful than these 

 delicate pieces of architecture, adapted with such a wealth and 

 diversity of form to their surroundings. In some species the 

 work of construction is shared by both sexes, in others the 

 female is responsible for the greater part, if not for the whole. 

 So industrious is the male Whitethroat that he may build 

 one or more nests even before a female has arrived, a 

 peculiarity to which I have referred, and which no doubt he 

 shares with other species. What is the meaning of such 

 exceptional industry ? In the opinion of Professor Groos, it 

 must be included in the category of "play," but, as the 

 history of the Whitethroat shows, such nests may be 

 structurally complete and ultimately made use of for the 

 purpose of reproduction. The females of the Willow Warbler 

 and Garden Warbler sometimes build one or more partial 

 nests before the final structure is commenced. We can trace 

 the reason of this in some instances. The Willow Warbler 

 that built four nests deserted the first, I believe, because of 

 constant persecution by the adjoining male. Some, however, 

 say that these loosely ordered platforms represent the initial 

 attempts of young birds, just as the Eeed Warbler's nest 

 woven to three reeds instead of more might be attributed to 

 a similar lack of experience. Could a few strands of decayed 

 vegetation laid crosswise here and there afford the necessary 

 data for experience ? And when we here speak of experience, 



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