148 RELATION OF SONG TO THE TERRITORY 



however, that the song, just as it serves to 

 attract the females, serves to repel other males, 

 a new element is introduced deserving of recogni- 

 tion ; for those males that had established 

 themselves would not only be spared the 

 necessity of many a conflict, but they would be 

 spared also the necessity of constant watchfulness, 

 and so, being free to pursue their normal routine 

 — to seek food, to rest, and, if migrants, to 

 recover from the fatigue of the journey, they 

 would be better fitted to withstand the strain of 

 reproduction ; and those that were still seeking 

 isolation in an appropriate environment, instead 

 of settling first here and then there only to find 

 themselves forestalled, would avoid and pass by 

 positions that were occupied, establishing them- 

 selves without loss of time in those that were 

 vacant. Without the aid of something beyond 

 mere physical encounter to regulate dis- 

 persal, it is difficult to imagine how in the 

 short time at disposal anything approaching 

 uniformity of distribution could be obtained. 

 Hence, both in the direction of limiting combat, 

 of insuring accommodation for the maximum 

 number of pairs in the minimum area, and of 

 conserving energy, the song, by conveying a 

 warning, plays an important part in the whole 

 scheme. 



And if this be so, if the song repels instead 

 of attracting, it follows that the more distinct 

 the sounds, the less likelihood will there be of 

 confusion ; for supposing that different species 

 were to develop similar songs, whole areas might 



