56 APRIL 



some naturalists hold, the cuckoo lays five eggs or 

 thereabouts, the balance of bird life in hitherto 

 understood conditions would be so upset that the 

 cuckoos would far outnumber the smaller birds and 

 gradually, through ousting them, would entail their 

 eventual disappearance. Yet the number of young 

 cuckoos seen in a single season is not in excess of 

 the old ones, and the obvious conclusion is that the 

 smaller birds are not so stupid as they have been 

 thought ; that they know and dislike the intrusion 

 of the cuckoo's egg ; and that in innumerable in- 

 stances resort has been had to the new storey in 

 the house, and the parasitical egg has been care- 

 fully buried when it has not been turned out of the 

 nest or destroyed. 



But instinct seems to fail the small birds just 

 where it might most reasonably be looked for. 

 When the young cuckoo is hatched the foster- 

 mother will starve herself to death rather than fail 

 to supply its ravenous demands. And when she is 

 dead the vociferant cries of the infant will attract 

 neighbouring birds, so that they come and continue 

 the supply, strangers though they are to the nest- 

 ling. A cuckoo in confinement has been known to 

 be fed by a wren, who brought food to the cage ; 

 and another, caged with some American blue 

 robins, had only to open its mouth and one of 

 the robins would drop all its tit-bits into the larger 

 bird's capacious maw. So that it seems as though 

 the instinct of certain species is proved to be of 

 absolute use to another species which thrives to its 

 detriment a condition which Darwin asserted to 

 be unknown. It is strange that one bird should be 



