Chap. XIll. LAW OF BATTLE. 43 



" males of the wild musk-duck {Cairina moscliata) ; 

 " and where these fiohts have occurred tlie river 

 ** is covered for some distance with feathers." ^ Birds 

 which seem ill-adapted for fighting engage in fierce 

 conflicts ; thus with the pelican the stKonger males 

 drive away the w^eaker ones, snapping with their 

 husre beaks and s^ivino- heaw blows with their wino;s. 

 Male snipes fight together, " tugging and pushing each 

 '"' other with tlieir bills in the most curious manner 

 " imaginable." Some few species are believed never to 

 fight ; this is the case, according to Audubon, with one 

 of the woodpeckers of the United States {Ficiis aiiratus), 

 althouo^h " the hens are follow^ed bv even half a dozen 

 " of their gay suitors." ^ 



The males of many birds are larger than the females, 

 and this no doubt is an advantage to them in their 

 battles with their rivals, and has been gained through 

 sexual selection. 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 Cincloram])lnis 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 here- 

 after see, the females apparently have acquired their 

 greater size and strength for the s^ake of conquering 

 other females and obtaining possession of the males. 



^ Sir E. Schomburgk, in 'Journal of E. Geograph. Soc' vol. xiii. 

 1843, p. 3L 



^ ' Ornithological Biography,' vol. i. p. 191. For pelicans and snipes, 

 see vol. iii. p. 381, 477. 



10 Gould, 'HandbookofBirdsof Australia,' vol. i. p. 395; vol. ii. p. 383. 



