4.58 TJie Descent of Man. Part II. 



there is a similar difference, the face and wing-coverts moreoyer 

 of the female being of a paler blue than in the male. 23 In the 

 family of the tits (Purina), which build concealed nests, the 

 female of our common blue tomtit {Paras cceruleus) is " much 

 " less brightly coloured " than the male ; and in the magnificent 

 Sultan yellow tit of India the difference is greater. 21 



Again in the great group of the woodpeckers/" 1 the sexes are 

 generally nearly alike, but in the Megapicus vulidas 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 colour might possibly make 

 the female dangerously conspicuous, whenever she put her head 

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

 colour, in accordance with Mr. Wallace's belief, had been elimi- 

 nated. This view is strengthened by what Malherbe states with 

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

 like the young males, have some crimson about their heads, 

 but that this colour disappears in the adult female, whilst it is 

 intensified in the adult male. Nevertheless the following con- 

 siderations render this view extremely doubtful : the male takes 

 a fair share in incubation, 26 and would be thus almost equally 

 exposed to cTanger; both sexes of many species have their heads 

 of an equally bright crimson ; in other species the difference 

 between 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 colouring of the head in the two sexes 

 often differs slightly in other ways. 



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

 colour 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 w T hich build open nests. 

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

 instance, without giving any details, the Australian pigeons. 27 

 It deserves especial notice that in all these cases the slight 



23 Every gradation of difference taken from M. Malherbe's mag- 



^etween the sexes may be followed nificent ' Monographie des Picide'es,' 



In the parrots of Australia. See 1861. 



Gould's 'Handbook,' &c, vol. ii. pp. 26 Audubon's ' Ornithological Bio- 



14-102. graphy,' vol. ii. p. 75; see also the 



* 4 Macgillivray's ' British Birds,' r ibis,' vol. i. p. 268. 



vol. ii. p. 433. Jerdon, ' Birds of 27 Gould's ' Handbook to th« 



India,' vol. ii. p. 282. Birds of Australia,' vol. ii. pp 109- 



25 All the foil .wing facts are 149. 







