466 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



He accounts for the singing of birds by the abounding energy of 



birds. 



We see that the inferior animals, when the conditions of life are favorable, 

 are subject to periodical fits of gladness, affecting them powerfully and stand- 

 ing out in vivid contrast to their ordinary temper. And we know what this feel- 

 ing is — this periodic intense elation which even civilized man occasionally ex- 

 periences when in perfect health, more especially when young. There are mo- 

 ments when he is mad with joy, when he can not keep still, when his impulse is 

 to sing and shout aloud and laugh at nothing, to run and leap and exert himself 

 in some extravagant way. Among the heavier mammalians the feeling is mani- 

 fested in loud noises, bellowings and screamings, and in lumbering, uncouth 

 motions — throwing up heels, pretended panics, and ponderous mock battles. 



This is simply a repetition of Herbert Spencer's surplus-energy 

 theory, which was based on the earlier theory of Schiller, who in his 

 letters " On the ^Esthetic Education of Mankind " wrote : 



Nature has indeed granted, even to the creature devoid of reason more than 

 the mere necessities of existence, and into the darkness of animal life has 

 allowed a gleam of freedom to penetrate here and there. When hunger no 

 longer torments the lion, and no beast of prey appears for hiin to fight, then 

 his unemployed power finds another outlet. He fills the wilderness with his 

 wild roars and his exuberant strength spends itself in aimless activity. In the 

 mere joy of existence, insects swarm in the sunshine, and it is certainly not 

 always the cry of want that we hear in the melodious rhythm of bird songs. 

 There is evidently freedom in these manifestations, but not freedom from all 

 necessity. The animal works when some want is the motive of his activity, 

 and plays when a superabundance of energy forms his motive when overflowing 

 life itself urges him to action. 



It is too superficial a theory to satisfy the modern mind. We are 

 compelled to ask the question, why does the male bird have more 

 surplus energy than the female? This question throws us back to a 

 consideration of the fundamental difference between the male and 

 the female. There is only one answer to that question. The male 

 sings more vigorously because he is a male, in other words because 

 there is some fundamental difference between the sexes. 



Karl Groos has contributed one very serious modification of the 

 Darwinian theory which has not been given sufficient consideration 

 by ornithologists, namely, that the song and antics of the male bird 

 are not for the purpose of compelling her choice by the female but 

 to overcome and break down her instinctive coyness. Nature has 

 given the female coyness as a dam to nature's impulses to prevent 

 the " too early and too frequent yielding of the sexual impulse." A 

 high degree of excitement is necessary to break this down and hence 

 the necessity for all the vigorous songs and antics of the male. 



I am confident that this theory is destined to find wider accept- 

 ance in the future than it has in the past, indeed, that a large part 

 of the song of birds before the nesting season is for the purpose of 

 breaking down the reluctance of the female rather than compelling 



