130 RELATION OP SONG TO THE TERRITORY 



The former evokes the normal reply, that is to 

 say the bird, if silent, is liable to utter a corre- 

 sponding reply ; the latter arouses hostility into 

 which is infused much feeling tone, the bird 

 sings hurriedly while in pursuit of its rival, 

 and, which is more remarkable still, even in the 

 midst of an encounter. Both the normal reply 

 and the emotional song must be similar in 

 origin different aspects of the same situa- 

 tion and both are clearly related to the other 

 male. 



The arrival of a female may also be followed 

 by an emotional outburst which can be heard 

 at intervals for some days ; on the other hand, 

 the song may continue as before or, for a time, 

 entirely cease. 



To take the emotional outburst first. This 

 would appear to be susceptible of explanation 

 on the hypothesis that the voice contributes to 

 a more effective pairing situation ; an hypothesis 

 which admittedly, at first sight, gains some 

 support from the fact that a second or a third 

 male is frequently present. But, in truth, the 

 presence of a second male makes the situation, 

 so far as the relationship between the song and 

 the female is concerned, all the more perplexing ; 

 for, as we have already seen, the instinct of 

 pugnacity, when aroused by the appearance of 

 an intruder, is also liable to be accompanied by 

 a similarly extravagant song. On each occasion 

 the vocal effort is infused with much feeling 

 tone, and it would be impossible to point to 

 any one feature which is peculiar to only one 



