86 SEXUAL SELECTION I BIEDS. Part IL 



in habit?, and our siskin, wliicli represents it still more 

 closely in structure, undergo no such annual change. 

 But a difference of this kind in the plumage of allied 

 species is not surprising, for with the common linnet, 

 which belongs to the same family, the crimson forehead 

 and breast are displayed only during the summer in 

 England, whilst in Madeira these colours are retained 

 throughout the year.'^^ 



Disj^hy hj Male Birds of their Plumage. — Ornaments 

 of all kinds, whether permanently or temporarily gained, 

 are sedulously displayed by the males, and apparently 

 serve to excite, or attract, or charm the females. But 

 the males will sometimes display their ornaments, when 

 not in the presence of the females, as occasionally occurs 

 with grouse at their balz-places, and as may be noticed 

 with the peacock ; this latter bird, however, evidently 

 wishes for a spectator of some kind, and will shew off 

 his finery, as I have often seen, before poultry or even 

 pigs.^° All naturalists who have closely attended to the 

 habits of birds, whether in a state of nature or under 

 confinement, are unanimously of opinion that the males 

 delight to display their beauty. Audubon frequently 

 speaks of the male as endeavouring in various ways to 

 charm the female. Mr. Gould, alter describing some 

 peculiarities in a male humming-bird, says he has no 

 doubt that it has the power of displaying them to the 

 greatest advantage before the female. Dr. Jerdon®^ 



79 On the pelican, see Sclater, in 'Proc. Zcol. Soc' 1868, p. 265. 

 On the American finches, see Audubon, ' Ornith. Biograpliy,' vol. i. p. 

 174, 221, and Jerdon, 'Birds of India,' vol. ii. p. 383. On the Frin- 

 gilla cannahina of Madeira, Mr, E. Vernon Harcourt, 'Ibis,' vol. v., 

 1863, p. 230. 



80 See also ' Ornamental Poultry,' by Eev. E. S. Dixon, 1848, p. 8. " 



81 'Birds of India,' introduct. vol. i. p. xxiv. ; on the peacock, vol. iii. 

 p. 507. See Gould's 'Introduction to the Trochilidaj,' 1 801, p. 15 and 111 . 



