142 RELATION OF SONG TO THE TERRITORY 



activity and leads to its establishment in a 

 definite place, and that it cannot search for a 

 mate because its freedom of action in this respect 

 is forbidden by law ; tliat the female inherits no 

 such disposition, that she is free to move from 

 place to place, free to satisfy her predominant 

 inclination, and to seek a mate where she wills ; 

 and, since the appropriate organic condition 

 which leads to pairing must coincide with 

 appropriate conditions in the environment, that 

 the union of the sexes must be accomplished 

 without undue delay. Furthermore we found 

 that a territory is essential if the offspring are to 

 be successfully reared ; that, since the available 

 breeding ground is limited, competition for it is 

 severe, and that the male is precluded from 

 leaving the ground which he has selected, and 

 is obliged, in order to secure a mate, to make 

 himself conspicuous. That was our general 

 result. Now there are two ways by which the 

 male can make himself conspicuous — by occupy- 

 ing such a position that he can be readily seen, or 

 by producing some special sound which will be 

 audible to the female and direct her to the spot. 

 The former, by itself, is insufficient ; in the dim 

 light of the early dawn, when life is at its highest, 

 and mating proceeds apace, what aid would it be 

 for a male to perch on the topmost branch of a 

 tree, how slender a guide in the depth of the 

 forest ? But whether in the twilight or in the 

 dark, in the thicket or the jungle, on the moun- 

 tain or on the moor, the voice can always be 

 heard — and the voice is the principal medium 





