Darwin s Theory of Sexual Selection 197 



" In regard to color, hardly anything need here be said, 

 for every one knows how splendid are the tints of many 

 birds, and how harmoniously they are combined. The col- 

 ors are often metallic and iridescent. Circular spots are 

 sometimes surrounded by one or more differently shaded 

 zones, and are thus converted into ocelli. Nor need much be 

 said on the wonderful difference between the sexes of many 

 birds. The common peacock offers a striking instance. 

 Female birds of paradise are obscurely colored and destitute 

 of all ornaments, whilst the males are probably the most 

 highly decorated of all birds, and in so many different ways, 

 that they must be seen to be appreciated. The elongated 

 and golden-orange plumes which spring from beneath the 

 wings of the Paradisea apoda, when vertically erected and 

 made to vibrate, are described as forming a sort of halo, in 

 the centre of which the head 'looks like a little emerald sun, 

 with its rays formed by the two plumes.' " 



Male humming-birds are almost as splendidly colored as 

 are the birds of paradise, some having the feathers modified 

 in a truly extraordinary way. "Almost every part of their 

 plumage has been taken advantage of, and modified ; and the 

 modifications have been carried, as Mr. Gould showed me, to 

 a wonderful extreme in some species belonging to nearly 

 every subgroup. Such cases are curiously like those which 

 we see in our fancy breeds, reared by man for the sake of 

 ornament : certain individuals originally varied in one charac- 

 ter, and other individuals of the same species in other charac- 

 ters ; and these have been seized on by man and much 

 augmented — as shown by the tail of the fantail pigeon, the 

 hood of the jacobin, the beak and wattle of the carrier, and 

 so forth. The sole difference between these cases is that 

 in the one the result is due to man's selection, whilst in 

 the other, as with humming-birds, birds of paradise, etc., it 

 is due to the selection by the females of the more beautiful 

 males." 



