96 THE STORY OF BIRD-LIFE. 



little or nothing to do with courting. It will be 

 found that the birds which have no song for the 

 most part have adopted other means for the 

 purposes of courtship; it may be by antics, if 

 may be battle. This is what is meant by sexual 

 selection. The preference of the female for the 

 finest performers gradually raises the standard 

 of the performance, in-as-much as the offspring 

 being begotten of parents with a higher aesthetic 

 taste and degree of skill thaa the unsuccessful 

 suitors, would cause each generation to slowly 

 improve upon the last. The excellence of their 

 performance to-day is the measure of the dis- 

 tance they have traversed from the dead level 

 of mediocrity. 



Of instrumental music we have not so many 

 instances, nor are they so varied. 



Our common British snipe {Gallinago coelestis) 

 affords us one of the best instances. In the 

 pairing season, and at this time only, it gives rise 

 to a most remarkable kind of noise, which has 

 been variously described as bleating, drumming, 

 neighing or thundering, according to the ear of 

 the listener. To the present writer it sounds 

 rather like humming, like the noise often made 

 by wind. Mr Darwin says, " This bird, during 

 the pairing-season, flies to 'perhaps a thousand 

 feet in height,' and after zig-zagiiing about for a 

 time, descends to the earth in a curved line with 

 outspread tail and quivering pinions and surpris- 

 ing velocity. The sound is emitted only during 

 this rapid descent. No one was able to explain the 

 cause, until Herr Meeves observed that on each 

 side of the tail the outer feathers are peculiarly 



