BIRD SONG HAWKINS. 473 



before him with her tail directed toward his head. Thus the sexual activity 

 displayed by the male comes to mean simply that he is more ardent at this 

 time than his mate. The advantage of this is obvious for thereby the more 

 vigorous males, by proclaiming their desire to pair, defeat their less vigorous 

 rivals, who might otherwise be chosen. The earlier they can take the held, 

 the more persistent their advances, the greater their chance of ultimate suc- 

 cess, and this because they slowly instill a preference which can not be over- 

 come by later and less virile comers. 



This fact makes it clear why many of the sober-tinted birds are as 

 ardent in their love dances and displays as some of the more bril- 

 liantly colored birds like the peacock and the pheasant. It may also 

 explain why some of the more brilliantly colored birds sing as vig- 

 orously as the duller-tinted species. Their nervous system is in a 

 condition of intense stimulation through the action of secretions 

 thrown off by the sex glands. But the important fact is that it com- 

 pletely modifies the theory of sexual selection, so modifying it that 

 there is little of the significance attributed to it by Darwin and his 

 followers remaining. The antics, display, and songs of birds are 

 germinal variations which have survived and are not the result of 

 conscious or unconscious choice on the part of the female. This is 

 " borne out by the fact that birds of the most sober hues affect dis- 

 plays of a character precisely similar in kind to those of birds in 

 which this display appears to be made for the sole purpose of exhib- 

 iting to the best advantage some specially modified or beautiful col- 

 ored feathers." 



This view which seeks the cause of song in the internal life of the 

 bird rather than in external causes also gives a more satisfactory 

 view of the total language of the bird, the call and alarm notes, the 

 gentle notes of the mother bird over her young, and the songs that 

 are uttered outside of the mating season. The sexual selection theory 

 has fallen down, in my judgment, from the fact that it has confined 

 itself too exclusively with one short period in the language of the 

 bird. It has failed almost exclusively to recognize that birds have a 

 language which extends throughout the entire year, either sign or 

 tone language, and that there must be something in the feathered 

 creature which will account for this less vigorous expression of life 

 and needs which occurs outside of the mating season. It is here that 

 the theory of germinal variations comes to our assistance. Voice 

 having originated in the hisses and groans of the reptile, it w r as in- 

 evitable that there should be a difference both of tone and vigor be- 

 tween the male and female birds, due to the essential difference of 

 sex and any variations in voice which might arise would be pre- 

 served in the male germ which assures the variation in the species 

 while the germ of the female guarantees the constancy of the species. 



