The Descent of Man

their vocal organs when excited by the strong
passions of love, jealousy and rage; but to this
point we shall recur when we treat of quadrupeds.
We have as yet spoken only of the voice, but
the males of various birds practise, during their
courtship, what may be called instrumental
music. Peacocks and Birds of Paradise rattle
their quills together. Turkey-cocks scrape their
wings against the ground, and some kinds of
grouse thus produce a buzzing sound. Another
North American grouse, the Tetrao umbellus,
when with his tail erect, his ruffs displayed, "he
shows off his finery to the females, who lie hid
in the neighbourhood," drums by rapidly striking
his wings together above his back, according
to Mr. R. Haymond, and not, as Audubon
thought, by striking them against his sides. The
sound thus produced is compared by some to
distant thunder, and by others to the quick roll
of a drum. The female never drums, "but flies