CHAPTER VIII 



THE LEAF-CUTTERS 



TT is not enough that animal industry should 

 be able, to a certain extent, to adapt itself 

 to casual exigencies when choosing the site of 

 a nest; if the race is to thrive, something else 

 is required, something which hide-bound in- 

 stinct is unable to provide. The Chaffinch, 

 for instance, introduces a great quantity of 

 lichen into the outer layer of his nest. This 

 is his method of strengthening the edifice and 

 making a stout framework in which to place 

 first the bottom mattress of moss, fine straw 

 and rootlets and then the soft bed of feathers, 

 wool and down. But, should the time-hon- 

 oured lichen be lacking, will the bird refrain 

 from building its nest? Will it forgo the 

 delight of hatching its brood because it has 

 not the wherewithal to settle its family in the 

 orthodox fashion? 



No, the Chaffinch is not perplexed by so 

 small a matter; he is an expert in materials, 

 he understands botanical equivalents. In the 



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