168 
SEXUAL selection: bieds. 
Part II. 
nacious and could defend themselves ; that those of the 
second group take extreme care in concealing their 
open nests, but this does not invariably hold good ; 
and that with the birds of the third group the females 
are brightly coloured chiefly on the under surface. Be- 
sides these cases the whole great family of pigeons, 
which are sometimes brightly, and almost always con- 
spicuously coloured, and which are notoriously liable to 
the attacks of birds of prey, offers a serious exception 
to the rule, for pigeons almost always build open and 
exposed nests. In another large family, that of the 
Humming-birds, all the species build open nests, yet 
with some of the most gorgeous species the sexes are 
alike ; and in the majority, the females, though less 
brilliant than the males, are very brightly coloured. 
Nor can it be maintained that all female humming- 
birds, which are brightly coloured, escape detection by 
their tints being green, for some display on their upper 
surfaces red, blue, and other colours.^^ 
In regard to birds which build in holes or construct 
domed nests, other advantages, as Mr. Wallace remarks, 
besides concealment are gained, such as shelter from 
the rain, greater warmth, and in hot countries protec- 
tion from the rays of the sun so that it is no valid 
Jerdon, ‘ Birds of India,’ vol. ii. p. 108. Gould’s ‘ Handbook of 
the Birds of Australia,’ vol. i. p. 463. 
12 por instance, the female Eupetoinena macroura has the head and 
tail dark blue with reddish loins ; the female Lampornis porphyrurus 
is blackish-green on the upper surface, with the lores and sides of the 
throat crimson ; the female Eulampis jugularis has the top of the head 
and back green, but the loins and the tail are crimson. Many other 
instances of highly conspicuous females could be given. See Mr. Gould’s 
magnificent work on this family. 
Mr. Salvin noticed in Guatemala (‘Ibis,’ 1864, p. 375) that hum- 
ming-birds were much more unwilling to leave their nests during very 
hot weather, when the sun w^as shining brightly, than during cool, 
cloudy, or rainy weather. 
