196 THE BIOLOGY OF BIRDS 



The way in which some birds, e.g. skylarks, steal snatches of 

 one another's music suggests the importance of imitation 

 as a factor in educating the vocal powers. 



Biologically regarded, the song is a partly instinctive, 

 partly deliberate endeavour on the male's part to attract his 

 desired mate's attention, to commend himself to her senses, 

 to excite her sex-interest, and to overcome her coyness. 

 There is a great deal to be said in support of Darwin's thesis, 

 elsewhere discussed, that the singing powers of the male 

 birds have been enhanced in the course of many generations 

 because the better singers tended to be more successful in 

 their love-making. But we must not think of a piece-meal 

 evolution. On the one hand, the song is the expression of 

 a unified organisation which includes strength of heart and 

 lungs as well as of vocal cords. On the other hand, we must 

 not think of the female bird listening with a critical ear, and 

 rejecting a suitor who makes a false note. It is rather that 

 she gives herself in the course of time to the male whose 

 total impression on her decisively excites her interest and 

 awakens her desire. 



But what we wish to add to the ordinary biological inter- 

 pretation is a recognition of the fact that birds are emotional 

 personalities, that to the passion of physical fondness there 

 has been added a joyous affection. We cannot prove this 

 for the bird, nor for our fellow-citizen. In both cases, it 

 looks as if it were so, and if our fellow-citizen denied it we 

 should not believe him. 



Emotion tends to be accompanied by motion. " And 

 then," as Wordsworth said, " my heart with pleasure fills, 

 and dances with the daffodils." In the courting bird the 

 internal motions associated with singing are in Hne with 

 the external movements of fluttering, leaping, dancing, and 

 soaring. Singing is an expression of emotional excitement. 



It is well known that when the young ones are hatched 

 out in the nightingale's nest, the male bird's lyric is replaced 

 by a solicitous parental croak, though he may recover his 

 voice and sing again if love's labour be lost before his con- 

 stitution changes for the year. But this simply implies that 



