SEXUAL SELECTION 517 



become much more pugnacious at the period when they 

 are most gayly ornamented. No doubt the males of some 

 obscurely colored birds fight desperately together, but it 

 appears that when sexual selection has been highly influen- 

 tial, and has given bright colors to the males of any species, 

 it has also very often given a strong tendency to pugnacity. 

 We shall meet with nearly analogous cases when we treat 

 of mammals. On the other hand, with birds the power of 

 song and brilliant colors have rarely been both acquired 

 by the males of the same species; but in this case the ad- 

 vantage gained would have been the same, namely, success 

 in charming the female. Nevertheless it must be owned 

 that the males of several brilliantly colored birds have had 

 their feathers specially modified for the sake of producing 

 instrumental music, though the beauty of this cannot be 

 compared, at least according to our taste, with that of the 

 vocal music of many songsters. 



We will now turn to male birds which are not orna- 

 mented in any high degree, but which nevertheless display 

 during their courtship whatever attractions they may pos- 

 sess. These cases are in some respects more curious than 

 the foregoing, and have been but little noticed. I owe the 

 following facts to Mr. Weir, who has long kept confined 

 birds of many kinds, including all the British Fringillidse 

 and EmberizidsB. The facts have been selected from a large 

 body of valuable notes kindly sent me by him. The bull- 

 finch makes his advances in front of the female, and then 

 puffs out his breast, so that many more of the crimson 

 feathers are seen at once than otherwise would be the case. 

 At the same time he twists and bows his black tail from 

 side to side in a ludicrous manner. The male chafiinch also 

 stands in front of the female, thus showing his red breast 

 and "blue bell," as the fanciers call his head; the wings at 

 the same time being slightly expanded, with the pure white 

 bands on the shoulders thus rendered conspi|!uous. The 

 common linnet distends his rosy breast, slightly expands 

 his brown wings and tail, so as to make the best of them 



