x COLOURS AND ORNAMENTS CHARACTERISTIC OF SEX 285 
descend rapidly from a great height. All these are probably 
recognition and call notes, useful to each species in relation 
to the most important function of their lives, and thus capable 
of being developed by the agency of natural selection. 
Decorative Plumage of Birds and its Display. 
Mr. Darwin has devoted four chapters of his Descent of 
Man to the colours of birds, their decorative plumage, and 
its display at the pairing season ; and it is on this latter 
circumstance that he founds his theory, that both the 
plumage and the colours have been developed by the prefer 
ence of the females, the more ornamented males becoming the 
parents of each successive generation. Any one Avho reads 
these most interesting chapters will admit, that the fact of the 
display is demonstrated ; and it may also be admitted, as highly 
probable, that the female is pleased or excited by the display. 
But it by no means follows that slight differences in the shape, 
pattern, or colours of the ornamental plumes are what lead a 
female to give the preference to one male over another; still 
less that all the females of a species, or the great majority of 
them, over a wide area of country, and for many successive 
generations, prefer exactly the same modification of the colour 
or ornament. 
The evidence on this matter is very scanty, and in most 
cases not at all to the point. Some peahens preferred an old 
pied peacock; albino birds in a state of nature have never 
been seen paired with other birds ; a Canada goose paired with 
a Bernicle gander; a male widgeon preferred a pintail duck 
to its own species; a hen canary preferred a male greenfinch 
to either linnet, goldfinch, siskin, or chaffinch. These cases 
are evidently exceptional, and are not such as generally occur 
in nature; and they only prove that the female does exert 
some choice between very different males, and some observa¬ 
tions on birds in a state of nature prove the same thing; but 
there is no evidence that slight variations in the colour or 
plumes, in the way of increased intensity or complexity, are 
what determines the choice. On the other hand, Mr. Darwin 
gives much evidence that it is not so determined. He tells us 
that Messrs. Hewitt, Tegetmeier, and Brent, three of the 
highest authorities and best observers, “ do not believe that 
