their slightly longer beaks. The flocks of males are often found
feeding on the seeds of the teazle (Dipsacus), which they can reach
with their elongated beaks, whilst the females more commonly feed on
the seeds of the betony or Scrophularia. With a slight difference of
this kind as a foundation, we can see how the beaks of the two sexes
might be made to differ greatly through natural selection. In some of
the above cases, however, it is possible that the beaks of the males
may have been first modified in relation to their contests with other
males; and that this afterwards led to slightly changed habits of life.
LAW OF BATTLE.
Almost all male birds are extremely pugnacious, using their beaks,
wings, and legs for fighting together. We see this every spring with
our robins and sparrows. The smallest of all birds, namely the
humming-bird, is one of the most quarrelsome. Mr. Gosse (3. Quoted by
Mr. Gould, Introduction to the Trochilidae, 1861, page 29.) describes
a battle in which a pair seized hold of each other s beaks, and whirled
round and round, till they almost fell to the ground; and M. Montes de
Oca, in speaking or another genus of humming-bird, says that two males
rarely meet without a fierce aerial encounter: when kept in cages
their fighting has mostly ended in the splitting of the tongue of one
of the two, which then surely dies from being unable to feed. (4.
Gould, ibid. p. 52.) With waders, the males of the common water-hen
(Gallinula chloropus) when pairing, fight violently for the females:
they stand nearly upright in the water and strike with their feet. Two
were seen to be thus engaged for half an hour, until one got hold of
the head of the other, which would have been killed had not the
observer interfered; the female all the time looking on as a quiet
spectator. (5. W. Thompson, Natural History of Ireland: Birds, vol.
ii. 1850, p. 327.) Mr. Blyth informs me that the males of an allied
bird (Gallicrex cristatus) are a third larger than the females, and are
so pugnacious during the breeding-season that they are kept by the
natives of Eastern Bengal for the sake of fighting. Various other birds
are kept in India for the same purpose, for instance, the bulbuls
(Pycnonotus hoemorrhous) which fight with great spirit. (6. Jerdon,
Birds of India, 1863, vol. ii. p. 96.)
[Fig. 37. The Ruff or Machetes pugnax (from Brehm s Thierleben ).]
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