198 
SEXUAL SELECTION: BIRDS. 
Part IL 
tints of both sexes of many birds had been acquired and 
preserved for the sake of protection, — for example, of 
the hedge-warbler or kitty-wren {Aceentor modularis and 
Troglodytes vulgaris), with respect to which we have no 
sufficient evidence of the action of sexual selection. 
We ought, however, to be cautious in concluding that 
colours which appear to us dull, are not attractive to the 
females of certain species ; we should bear in mind such 
cases as that of the common house-sparrow, in which 
the male differs much from the female, but does not 
exhibit any bright tints. No one probably will dispute 
that many gallinaceous birds which live on the open 
ground have acquired their present colours, at least in 
part, for the sake of protection. We know how wull they 
are thus concealed ; we know that ptarmigans, whilst 
changing from their winter to their summer plumage, 
both of which are protective, suffer greatly from birds 
of prey. But can we believe that the very slight dif- 
ferences in tints and markings between, for instance, 
the female black and red-grouse serve as a protection ? 
Are partridges, as they are now coloured, better pro- 
tected than if they had resembled quails? Do the 
slight differences between the females of the common 
pheasant, the Japan and golden pheasants, serve as a 
protection, or might not their plumages have been 
interchanged with impunity? From what Mr. Wal- 
lace has observed of the habits of certain gallinaceous 
birds in the East he thinks that such slight differences 
are beneficial. For myself, I will only say that I am 
not convinced. 
Formerly when I was inclined to lay much stress on 
the principle of protection, as accounting for the less 
bright colours of female birds, it occurred to me that 
possibly both sexes and the young might aboriginally 
have been brightly coloured in an equal degree ; but 
