but as the black-cock continues his spel for hours during successive
days, and in the case of the capercailzie with an agony of passion,
we are led to suppose that the females which are present are thus
charmed. (50. L. Lloyd, The Game Birds of Sweden, etc., 1867, pp. 22,
81.) The voice of the common rook is known to alter during the
breeding-season, and is therefore in some way sexual. (51. Jenner,
Philosophical Transactions, 1824, p. 20.) But what shall we say about
the harsh screams of, for instance, some kinds of macaws; have these
birds as bad taste for musical sounds as they apparently have for
colour, judging by the inharmonious contrast of their bright yellow and
blue plumage? It is indeed possible that without any advantage being
thus gained, the loud voices of many male birds may be the result of
the inherited effects of the continued use of 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 directly to the place where the male is thus
engaged. The male of the Kalij-pheasant, in the Himalayas, often makes
a singular drumming noise with his wings, not unlike the sound produced
by shaking a stiff piece of cloth. On the west coast of Africa the
little black-weavers (Ploceus?) congregate in a small party on the
bushes round a small open space, and sing and glide through the air
with quivering wings, which make a rapid whirring sound like a child s
rattle. One bird after another thus performs for hours together, but
only during the courting-season. At this season, and at no other time,
the males of certain night-jars (Caprimulgus) make a strange booming
noise with their wings. The various species of woodpeckers strike a
sonorous branch with their beaks, with so rapid a vibratory movement
that the head appears to be in two places at once. The sound thus
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