30 EVOLUTION OF BIRD-SONG 



their rapacious enemies, although in certain species 

 this knowledge is to some extent inherited, as it is 

 in the common fowl. In relation to this interesting 

 matter the following remarks by Mr. Hudson are in 

 point : — " Another proof that the nestling has ab- 

 solutely no instinctive knowledge of particular 

 enemies, but is taught to fear them by the parents, 

 is to be found in the striking contrast between the 

 habits of parasitical and genuine young in the nest 

 and after they have left it, while still unable to find 

 their own food. I have had no opportunities of 

 observing the habits of the young cuckoo in 

 England with regard to this point, and do not know 

 whether other observers have paid any attention to 

 the matter or not, but I am very familiar with the 

 manners of the parasitical starling or cow - bird of 

 South America. The warning cries of the foster- 

 parent have no effect on the young cow-bird at any 

 time. Until they are able to fly, they will readily 

 devour worms from the hand of a man, even when 

 the old birds are hovering close by and screaming 

 their danger-notes, and while their own young, if the 

 parasite has allowed any to survive in the nest, are 

 crouching down in the greatest fear. After the 

 cow-bird has left the nest it is still stupidly tame ; 

 and more than once I have seen one carried off from 



