3i6 THE WONDER OF LIFE 



expense of eggs or oSspring of their own, which the 

 young cuckoo ejects from their proper cradle. ' The 

 price of rearing every cuckoo is the total and invari- 

 able destruction of the offspring of the dupe '. The 

 question that so many naturahsts have asked is, ' Why 

 doesn't the cuckoo brood ' ? Darwin accepted the answer 

 that the parasitic habit was an adaptation to the fact 

 that the mother-cuckoo lays her eggs, not daily as most 

 birds do, but at intervals of two or three days. Since 

 the American cuckoos, which build their own nests and 

 rear their own young, have the same peculiarity of inter- 

 rupted egg-laying, Darwin had further to suppose that 

 these were just beginning to lose their nesting instincts — 

 a view which the careful studies of Francis H. Herrick do 

 not at aU confirm. 



The important facts in regard to the European cuckoo 

 must first be recalled. The breeding range extends over 

 a large part of Europe and Asia. In the autumn migration, 

 the adults leave the young to migrate independently at 

 a later date. The familiar Spring call is made by the 

 male ; the female's note is quite different, ' suggest- 

 ing the sound of bubbling water '. She is polyandrous, for 

 a time at least, there being five or more males to every 

 female. Some authorities maintain that there is no true 

 pairing. 



It seems impossible to doubt that the bird used to build 

 a nest and brood in former days, but there is no certain 

 case of brooding cuckoos {Cuculus canorus). Careful 

 ornithologists have spoken of the bird scheming, playing a 

 trick, watching the result of smuggling her egg into the 

 chosen nest, and even Baldamus writes : ' The female 

 cuckoo, with or without a male, and either before or after 



