94 
SEXUAL selection: birds. 
Part II. 
together, but it appears that when sexual selection 
has been highly influential, and has given bright 
colours 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 colours have rarely been both 
acquired by the males of the same species ; but in this 
case, the advantage gained would have been identically 
the same, namely success in charming the female. 
Nevertheless it must be owned that the males of several 
brilliantly-coloured birds have had their feathers spe- 
cially 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 
urnamented in any very high degree, but which 
nevertheless display, during their courtship, whatever 
attractions they may possess. These cases are in some 
respects more curious than the foregoing, and have been 
but little noticed. I owe the following facts, selected 
from a large body of valuable notes, sent to me by Mr. 
Jenner Weir, who has long kept birds of many kinds, in- 
cluding all the British Fringillidse and Emberizidae. The 
bullfinch 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 chaffinch also stands in front of the female, thus 
shewing 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 conspicuous. The common linnet distends 
