the sword or spear.

Among birds, the contest is often of a more peaceful character. All
those who have attended to the subject, 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 with the most
elaborate care, and show off in the best manner, their gorgeous plumage;
they likewise 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 a pied peacock was eminently attractive to all his hen
birds. I cannot here enter on the necessary details; but if man can in a
short time give beauty and an elegant carriage 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. Some well-known laws, with respect to the plumage of
male and female birds, in comparison with the plumage of the young, can
partly be explained through the action of sexual selection on variations
occurring at different ages, and transmitted to the males alone or to
both sexes at corresponding ages; 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, by individual males having had, in successive
generations, some slight advantage over other males, in their weapons,
means of defence, or charms; which they have transmitted to their
male offspring alone. Yet, I would not wish to attribute all sexual
differences to this agency: for we see in our domestic animals
peculiarities arising and becoming attached to the male sex, which
apparently have not been augmented through selection by man. The tuft of
hair on the breast of the wild turkey-cock cannot be of any use, and it
is doubtful whether it can be ornamental in the eyes of the female bird;
indeed, had the tuft appeared under domestication it would have been
called a monstrosity.

ILLUSTRATIONS OF THE