THE LOVE DISPLAYS OF BIRDS 225 



birds alone ; in other species they are common 

 to both sexes, but in these cases the males are 

 generally the most specialised. As one of the 

 most familiar instances of feather modification 

 for the purpose of producing sound, we may 

 mention the tail of the Common Snipe. In this 

 species the outermost rectrices have a stiff sabre- 

 shaped shaft ; but it seems extremely doubtful 

 whether the drumming sound that this Snipe 

 makes in spring is produced entirely by this 

 modification. It appears to be caused by the 

 combined action of the wings and tail. During 

 the love season the male Snipe, as if to parade 

 his inordinate vanity, soars far up into the air, 

 then suddenly descends on vibrating wings and 

 outspread tail, making the peculiar bleating 

 noise which seems to be produced by the air 

 waves being driven by the powerful wing-beats 

 through the expanded and rigid tail feathers. 

 There are other species of Snipe in which the 

 tail feathers are modified in a much more 

 remarkable manner, as, for instance, in the Pin- 

 tail Snipe (Scolopax stenura) of East Asia. 

 This bird has no fewer than twenty-six rec- 

 trices, the outermost being little more than 

 threads. The sound produced by this modifica- 

 tion appears not to have been described by 



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