BIRDS. 479 



What then are we to conclude from these facts and con- 

 siderations? Does the male parade his charms with so 

 much pomp and rivalry for no purpose? Are we not justi- 

 fied in believing that the female exerts a choice, and that 

 she receives the addresses of the male who pleases her most? 

 It is not probable that she consciously deliberates ; but 

 she is most excited or attracted by the most beautiful, or 

 melodious, or gallant males. Nor need it be supposed that 

 the female studies each stripe or spot of color ; that the 

 peahen, for instance, admires each detail in the gorgeous 

 train of the peacock she is probably struck only by tlie 

 general effect. Nevertheless, after hearing how carefully 

 tlie male Argus pheasant displays his elegant primary wing- 

 feathers and erects his ocellated plumes in the right posi- 

 tion for their full effect; or again, how the male goldfinch 

 alternately displays his gold-bespangled wings, we ought 

 not to feel too sure that the female does not attend to each 

 detail of beauty. We can judge, as already remarked, of 

 choice being exerted, only from analogy; and the mental 

 powers of birds do not differ fundamentally from ours. 

 From these various considerations we may conclude that 

 the pairing of birds is not left to chance; but that those 

 males, which are best able by their various charms to please 

 or excite the female, are under ordinary circumstances 

 accepted. If this be admitted, there is not much difficulty 

 in understanding how male birds have gradually acquired 

 their ornamental characters. All animals present individ- 

 ual differences, and as man can modify his domesticated 

 birds by selecting the individuals which appear to him the 

 most beautiful, so the habitual or even occasional preference 

 by the female of the more attractive males would almost 

 certainly lead to their modification; and such modifications 

 might in the course of time be augmented to almost any 

 extent, compatible with the existence of the species. 



Variability of Birds, a7id Especially of TJieir Secondary 

 Sexual Characters. Variability and inheritance are the 

 foundations for the work of selection. That domesticated 

 birds have varied greatly, their variations being inherited, 

 is certain. That birds in a state of nature have been modi- 

 fied into distinct races is now universally admitted. * Vari- 



* According to Dr. Blasius (" Ibis," vol. ii, 1860, p. 297), there are 

 425 indubitable species of birds which breed in Europe, besides sixty 



