pies have a still more curious
method of call, by rapping on dry and sonorous branches, which they
use not only to attract the female, but also to charm her. We may say
that these birds perform instrumental music.[75]

The exercise of vocal power among birds seems to be complementary to
the development of accessory plumes and ornaments. All our finest
singing birds are plainly coloured, with no crests, neck or tail
plumes to display. The gorgeously ornamented birds of the tropics have
no song, and those which expend much energy in display of plumage, as
the turkey and peacocks, have comparatively an insignificant
development of voice.[76] The extraordinary manner in which birds
display their plumage at the time of courting is well known. Let us
take one example--the courtship of the Argus pheasant. This bird is
noted for the extreme beauty of the male's plumage. Its courtship has
been beautifully observed by H.O. Forbes--[77]

"It is the habit of this bird to make a large circus, some ten
or twelve feet in diameter, in the forest, which it clears of
every leaf and twig and branch, till the ground is perfectly
swept and garnished. On the margin of this circus there is
invariably a projecting branch or high arched rest, at a few
feet elevation from the ground on which the female bird takes
its place, while in the ring the male--the male bird alone
possesses great decoration--shows off all its magnificence for
the gratification and pleasure of his consort, and to exalt
himself in her eyes."

In this picture we have all the characteristic features of the display
of personal beauty in which many birds delight. Any one may see such
performances for themselves. The male chaffinch, for instance, will
place himself in front of the female that she may admire at her ease
his red throat and blue head; the bullfinch swells out his breast to
display the crimson feathers, twisting his black tail from side to
side; the goldfinch sways his body, and quickly turns his slightly
expanded wings first to one side, then to the other, with a golden
flashing effect.[78] Even birds of less ornamental plumage are
accustomed to strut and show themselves off before the females. Birds
often assemble in large numbers to compete in beauty before pairing.
The _Tetras cuspido_ of Florida and the little grouse of Germany and
Scandinavia do this. The latter have daily amorous assemblies, or
_cours d'amour_, of g