THE



209



Hvtcultural flfoagasme,


BEING THE JOURNAL OF THE


AVICULTURAL SOCI ETY.



Third Series — VOL. Ill, — NO. 8 .—All rights reserved. JUNE, 1912 .


NOTES ON SEXUAL SELECTION.


By Frank Finn, B.A., F.Z.S.


Part I.


As most of my readers know, Darwin’s celebrated theory

of Sexual Selection argues that the superiority in appearance of

male birds, so often notable, is due to the selection, through

untold ages, of the handsomest males by the hens; and, as there

is extremely little direct evidence in favour of this view, and

what little there is has been chiefly furnished by aviculturists, it

seems worth while to review the subject; since the theory will

in the end probably have to stand or fall on the verdict of avi¬

culturists, who are or should be, I have always maintained, the

most truly scientific of ornithologists, our hobby giving us the

most perfect control of the only scientific method, that of obser¬

vation and experiment.


I11 the first place it is as well to enumerate briefly the

forms taken by sex-differences among birds, choosing one’s

examples as much as possible from species well-known in avi¬

culture. We find then, where the male is the superior sex

the following forms of difference:—


I. Male similar to female in size (or nearly so) and structure,

but richer in colour :—European Chaffinch (Fringilla

ccelebs ), Scarlet Tanager ( Rhaviphoccelus brasilius ) and

numberless others, this being far the commonest form

of sex-difference.


II. Male not only richer in plumage than female, but possessing

special structural decorations :—Common Fowl (Gallus

gallus), Peacock (Pavo cristatus), the Birds of Paradise

and many others, this being the next commonest type.



