452 THE DESCENT OP MAN. 



"colored" than the male; and in the magnificent Sultan yellow tit 

 of India the difference is greater.^* 



Again in the great army of the woodpeclcers,^ the sexes are 

 generally nearly alilie, but in the Megapicus validus all those 

 parts of the head, neck, and breast, which are crimson in the 

 male are pale brown in the female. As in several woodpeckers 

 the head of the male is bright crimson, whilst that of the female 

 is plain, it occurred to me that this color might possibly make 

 the female dangerously conspicuous, whenever she put her head 

 out of the hole containing her nest, and consequently that this 

 color, in accordance with Mr. Wallace's belief, had been elim- 

 inated. This view is strengthened by what Malherbe states with 

 respect to Indopicus carlotta; namely, that the young females, 

 like the joung males, have some crimson about their heads, but 

 that this color disappears in the adult female, whilst it is inten- 

 sified in the adult male. Nevertheless the following considera- 

 tions render this view extremely doubtful: the male takes a 

 fair share in incubation,^" and would be thus almost equally ex- 

 posed to danger; both sexes of many species have their heads 

 of an equally bright crimson; in other species the difference be- 

 tween the sexes in the amount of scarlet is so slight that it can 

 hardly make any appreciable difference in the danger incurred; 

 and lastly, the coloring of the head in the two sexes often differs 

 slightly in other ways. 



The cases, as yet given, of slight and graduated differences in 

 color between the males and females in the groups, in which as 

 a general rule the sexes resemble each other, all relate to species 

 which build domed or concealed nests. But similar gradations 

 may likewise be observed in groups in which the sexes as a 

 general rule resemble each other, but which build open nests. 

 As I have before instanced the Australian parrots, so I may here 

 instance, without giving any details, the Australian pigeons.-' 

 It deserves especial notice that in all these cases the slight dif- 

 ferences in plumage between the sexes are of the same general 

 nature as the occasionally greater differences. A good illustra- 

 tion of this fact has already been afforded by those kingfishers in 

 which either the tail alone or the whole upper surface of the 

 plumage differs in the same manner in the two sexes. Similar 

 cases may be observed with parrots and pigeons. The differences 



^ Macg-illivray's 'British Birds,' vol. ii. p. 433. Jerdon, 'Birds of In- 

 dia,' vol. ii. p. 282. 



■' All tlie foliowing facts are taken from M. Malherbe's mag-nificent 

 'MonogTapliie des Picidees,' 1861. 



^ Audubon's 'Ornithological Biography,' vol. ii. p. 75; see, also, the 

 'Ibis,' vol. i. p. 268. 



2' Gould's 'Handbook to the Birds of Australia,' vol. ii. pp. 109-149. 



