4Jhap. XIll. 
LAW OF BATTLE, 
43 
males of the wild musk-duck (Cairina moschata ) ; 
and where these fights have occurred the river 
is covered for some distance with feathers.”® Birds 
which seem ill-adapted for fighting engage in fierce 
conflicts ; thus with the pelican the stronger males 
drive away the weaker ones, snapping with their 
huge beaks and giving heavy blows with their wings. 
Male snipes fight together, tugging and pushing each 
other with their 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 (Ficus auratus), 
although the hens are followed by 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 Gincloramplius 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, 
wdll not suffice. In some few cases, as we shall here- 
after see, the females apparently have acquired their 
greater size and strength for the sake of conquering 
other females and obtaining possession of the males. 
^ Sir K. Schombiirgk, in ‘Journal of K. Geograph. Soc/ vol. xiii. 
1843, p. 31. 
^ ‘ Ornithological Biography,’ vol. i. p. 191. For pelicans and snipes, 
see vol. iii. p. 381, 477. 
Gould, ‘Handbook of Birds of Australia,’ vol. i. p. 395 ; vol. ii. p. 383. 
