NATURALIST IN BRAZIL 



bumble-bees and the songs of the birds with a curious xylophonic 

 accompaniment. 



But if the voices of birds and animals are intended to bring the sexes 

 together, why do the birds continue to sing and the frogs to croak 

 after they have found their mates? When a pair of birds have buUt 

 their nest and laid their eggs, the cock bird still goes on singing, 

 and yet there is now no question of the necessity of finding and 

 recognizing one another. 



Darwin, in his work on Sexual Selection, sought to explain this 

 circumstance by the theory of selection by the female. According to 

 this doctrine, the bird sings in order to arouse desire in his mate. 

 Darwin, indeed, was even of the opinion that the voices of the birds 

 had evolved into actual song because the hen birds have always 

 listened most willingly to the best singers, as these excited them 

 more effectively. Consequently the good singers found mates; they 

 were the fathers of the next generation, which, since it was begotten 

 by such fathers, must have possessed a similar gift of song. But of 

 these the most gifted singers were once more chosen by the females ; 

 and so the vocal art improved from generation to generation. 



Illuminating as this theory may sound, I have always had my 

 doubts as to its value when I have listened to the birds singing in 

 forest and meadow, and have watched them as they sang. For if 

 the song of the cock bird is intended for the hen, one has at least 

 the right to expect that the latter shall hear it ! But more often than 

 not she is nowhere to be seen; she is not concerned with the song 

 of the cock, and never approaches in order to hear it better. A 

 thrush may be fluting ever so bravely in a tree-top ; the hen bird is 

 never found sitting beside him, listening in rapture. If I have looked 

 about for her I have generally found her on the ground, pulling 

 an earthworm from the soil, or working at her nest. As for the cock, 

 he does not seem in the very least degree anxious that the hen should 

 admire his skill. If he were anxious to charm her by his song, he would 

 at least approach her ! But he prefers to sit in the tree-top, singing 

 to the world at large, as though no hens existed ! And every bird- 

 fancier knows that if one puts a hen into the cage of a singing cock, 

 the latter, so far from singing twice as well, as one would expect 

 in the light of Darwin's theory, simply ceases to sing at all ! 



On the other hand, if one wishes a cock canary to do his best 

 one must not give him a mate. But the presence of another cock 

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