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Descent of Man [ 1871]

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Author Topic: Descent of Man [ 1871]  (Read 5938 times)
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« Reply #120 on: February 09, 2009, 03:11:34 pm »

The males of many birds are larger than the females, and this no
doubt is the result of the advantage gained by the larger and stronger
males over their rivals during many generations. The difference in
size between the two sexes is carried to an extreme point in several
Australian species; thus the male musk-duck (Biziura), and the male
Cincloramphus cruralis (allied to our pipits) are by measurement
actually twice as large as their respective females.* With many
other birds the females are larger than the males; and, as formerly
remarked, the explanation often given, namely, that the females have
most of the work in feeding their young, will not suffice. In some few
cases, as we shall hereafter see, the females apparently have acquired
their greater size and strength for the sake of conquering other
females and obtaining possession of the males.

  * Gould, Handbook of Birds of Australia, vol. i., p. 395; vol.
ii., p. 383.

  The males of many gallinaceous birds, especially of the polygamous
kinds, are furnished with special weapons for fighting with their
rivals, namely spurs, which can be used with fearful effect. It has
been recorded by a trustworthy writer* that in Derbyshire a kite
struck at a game-hen accompanied by her chickens, when the **** rushed
to the rescue, and drove his spur right through the eye and skull of
the aggressor. The spur was with difficulty drawn from the skull,
and as the kite, though dead, retained his grasp, the two birds were
firmly locked together; but the **** when disentangled was very little
injured. The invincible courage of the game-**** is notorious: a
gentleman who long ago witnessed the brutal scene, told me that a bird
had both its legs broken by some accident in the cockpit, and the
owner laid a wager that if the legs could be spliced so that the
bird could stand upright, he would continue fighting. This was
effected on the spot, and the bird fought with undaunted courage until
he received his death-stroke. In Ceylon a closely allied, wild
species, the Gallus stanleyi, is known to fight desperately "in
defence of his seraglio," so that one of the combatants is
frequently found dead.*(2) An Indian partridge (Ortygornis gularis),
the male of which is furnished with strong and sharp spurs, is so
quarrelsome "that the scars of former fights disfigure the breast of
almost every bird you kill."*(3)

  * Mr. Hewitt, in the Poultry Book, by Tegetmeier, 1866, p. 137.
  *(2) Layard, Annals and Magazine of Natural History, vol. xiv.,
1854, p. 63.
  *(3) Jerdon, Birds of India, vol. iii., p. 574.

  The males of almost all gallinaceous birds, even those which are not
furnished with spurs, engage during the breeding- season in fierce
conflicts. The capercailzie and black-**** (Tetrao urogallus and T.
tetrix), which are both polygamists, have regular appointed places,
where during many weeks they congregate in numbers to fight together
and to display their charms before the females. Dr. W. Kovalevsky
informs me that in Russia he has seen the snow all bloody on the
arenas where the capercailzie have fought; and the black-cocks "make
the feathers fly in every direction," when several "engage in a battle
royal." The elder Brehm gives a curious account of the balz, as the
love-dances and love songs of the black-**** are called in Germany.
The bird utters almost continuously the strangest noises: "he holds
his tail up and spreads it out like a fan, he lifts up his head and
neck with all the feathers erect, and stretches his wings from the
body. Then he takes a few jumps in different directions sometimes in a
circle, and presses the under part of his beak so hard against the
ground that the chin feathers are rubbed off. During these movements
he beats his wings and turns round and round. The more ardent he grows
the more lively he becomes, until at last the bird appears like a
frantic creature." At such times the black-cocks are so absorbed
that they become almost blind and deaf, but less so than the
capercailzie: hence bird after bird may be shot on the same spot, or
even caught by the hand. After performing these antics the males begin
to fight: and the same black-****, in order to prove his strength over
several antagonists, will visit in the course of one morning several
balz places, which remain the same during successive years.*

  * Brehm, Illust. Thierleben, 1867, B. iv., s. 351. Some of the
foregoing statements are taken from L. Lloyd, Game Birds of Sweden,
&c., 1867, p. 79.

  The peacock with his long train appears more like a dandy than a
warrior, but he sometimes engages in fierce contests: the Rev. W.
Darwin Fox informs me that at some little distance from Chester two
peacocks became so excited whilst fighting, that they flew over the
whole city, still engaged, until they alighted on the top of St.
John's tower.
  The spur, in those gallinaceous birds which are thus provided, is
generally single; but Polyplectron (see fig. 51) has two or more on
each leg; and one of the blood-pheasants (Ithaginis cruentus) has been
seen with five spurs. The spurs are generally confined to the male,
being represented by mere knobs or rudiments in the female; but the
females of the Java peacock (Pavo muticus) and, as I am informed by
Mr. Blyth, of the small fire-backed pheasant (Euplocamus
erythropthalmus) possess spurs. In Galloperdix it is usual for the
males to have two spurs, and for the females to have only one on
each leg.* Hence spurs may be considered as a masculine structure,
which has been occasionally more or less transferred to the females.
Like most other secondary sexual characters, the spurs are highly
variable, both in number and development, in the same species.

  * Jerdon, Birds of India: on Ithaginis, vol. iii., p. 523; on
Galloperdix, p. 541.
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