40 SEXUAL SELECTION : BIRDS. Pakt II. 



am assured by Mr. J. Jenner Weir that tlie bird- 

 catchers can distinguish the males by their slightly 

 longer beaks. The flocks of males, as an old and trust- 

 worthy bird-catcher asserted, are commonly found feed- 

 ing 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 nature 

 as a foundation, we can see how the beaks of the two 

 sexes might be made to differ greatly through natural 

 selection. In all these eases, however, especially in 

 tliat of the quarrelsome humming-birds, it is possible 

 that the differences in the beaks may have been first 

 acquired by the males in relation to their battles, and 

 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 hum- 

 ming-bird, is one of the most quarrelsome. Mr. Gosse ^ 

 describes a battle, in which a pair of humming-birds 

 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 of another genus, 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."^ With 

 Waders, the males of the common water-hen (GaUinuIa 

 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 



3 Quoted by Mr. Gould, ' Introduction to the Trochilidse,' 1861, p. 29. 

 * Gould, ibid. p. 52. 



