86 
SEXUAL SELECTION: BIEDS. 
Part II.. 
in liaMts^ and our siskin, which 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 yearJ^ 
Display by 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, wEen 
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 
pig’s.^® 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, after 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. Zool. See.’ 1868, p. 265. 
On the American finches, see Andubon, ‘ Ornith. Biography,’ vol. i. 
174, 221, and Jerdon, ‘ Birds of India,’ vol. ii. p. 383. On the Frin- 
gilla cannabina of Madeira, Mr. E. Vernon Harconrt, ‘Ibis,’ vol. v.,, 
*1863, p. 230. 
^0 See also ‘ Ornamental Poultry,’ by Eev. E. S. Dixon, 1848, 8. 
SI ‘Birds of India,’ introduct. vol. i. p. xxiv. ; on the peacock, vol. iii. 
p. 507. See Gould’s ‘Introduction to the Trochilidae,’ 1861, p. 15 and 111 
