THE PLAY OF ANIMALS. 281 



volume of sound as of a high wind when heard at a dis- 

 tance/' and this takes place daily for hours at a time. 

 But during his courtship the male has but " a feeble, 

 sketchy music," regaining his skill only after the nest 

 is built. This is a more valuable example than Spen- 

 cer's, for he observed only a single bird that may have 

 been sick at the time for pairing, while Hudson's obser- 

 vation refers to a whole species. Yet the phenomenon 

 is too rare to have any weight against the overwhelming 

 mass of evidence for the view that song in general 

 belongs to courtship. It is wiser to seek some special 

 explanation of these irregular cases, and also to bear in 

 mind that " better " and " worse " are relative terms. 

 A song broken by the restless motions of an excited 

 bird may seem not so good to the listener as the same 

 strain produced when the singer is quiet and his notes 

 are therefore louder and more continuous. There is 

 also a possibility that song is sometimes supplanted by 

 the disproportionate evolution of other courtship arts — 

 the finch spoken of by Hudson has unusual powers of 

 flight and skill in dancing. However, I do not profess 

 to find an adequate answer in these suppositions to this 

 undeniable difficulty. 



Those instances in which the bird expresses his ex- 

 citement by means of a kind of instrumental music, 

 instead of doing it vocally, are also very remarkable. 

 Darwin has a long series of such examples. Peacocks 

 rattle the quills of their tails, and birds of paradise do 

 the same thing, during their courtship. Woodpeckers 

 call the females by striking the bill very rapidly on dry 

 wood, making in this way a sort of drumming sound. 

 Turkeycocks scrape their wings on the ground. Many 

 birds make a kind of whirring sound in flight; a familiar 

 instance is the " beating " of army snipes as they mount 



