ar wounds from the huge mandibles of other
males. The war is, perhaps, severest between the males of polygamous
animals, and these seem oftenest provided with special weapons. The males
of carnivorous animals are already well armed; though to them and to
others, special means of defence may be given through means of sexual
selection, as the mane to the lion, the shoulder-pad to the boar, and the
hooked jaw to the male salmon; for the shield may be as important for
victory, as the sword or spear.

Amongst birds, the contest is often of a more peaceful character. All those
who have attended to the subject, {89} believe that there is the severest
rivalry between the males of many species to attract by singing the
females. The rock-thrush of Guiana, birds of Paradise, and some others,
congregate; and successive males display their gorgeous plumage and perform
strange antics before the females, which, standing by as spectators, at
last choose the most attractive partner. Those who have closely attended to
birds in confinement well know that they often take individual preferences
and dislikes: thus Sir R. Heron has described how one pied peacock was
eminently attractive to all his hen birds. It may appear childish to
attribute any effect to such apparently weak means: I cannot here enter on
the details necessary to support this view; but if man can in a short time
give elegant carriage and beauty to his bantams, according to his standard
of beauty, I can see no good reason to doubt that female birds, by
selecting, during thousands of generations, the most melodious or beautiful
males, according to their standard of beauty, might produce a marked
effect. I strongly suspect that some well-known laws, with respect to the
plumage of male and female birds, in comparison with the plumage of the
young, can be explained on the view of plumage having been chiefly modified
by sexual selection, acting when the birds have come to the breeding age or
during the breeding season; the modifications thus produced being inherited
at corresponding ages or seasons, either by the males alone, or by the
males and females; but I have not space here to enter on this subject.

Thus it is, as I believe, that when the males and females of any animal
have the same general habits of life, but differ in structure, colour, or
ornament, such differences have been mainly caused by sexual selection;
that is, individual males have had, in successive generations