270 
THE PRINCIPLES OF 
Part II. 
be polygamous. With the Grallatores, extremely few 
species differ sexually, but the ruff (. Machetes pugnax) 
affords a strong exception, and this species is believed 
by Montagu to be a polygamist. Hence it appears 
that with birds there often exists a close relation 
between polygamy and the development of strongly- 
marked sexual differences. On asking Mr. Bartlett, at 
the Zoological Gardens, who has had such large ex- 
perience with birds, whether the male tragopan (one of 
the Gallinaceae) was polygamous, I was struck by his 
answering, “ I do not know, but should think so from 
“ his splendid colours.” 
It deserves notice that the instinct of pairing with a 
single female is easily lost under domestication. The 
wild-duck is strictly monogamous, the domestic-duck 
highly polygamous. The Bev. W. D. Fox informs me 
that with some half-tamed wild-ducks, kept on a large 
pond in his neighbourhood, so many mallards were shot 
by the gamekeeper that only one was left for every 
seven or eight females; yet unusually large broods 
were reared. The guinea-fowl is strictly monogamous ; 
but Mr. Fox finds that his birds succeed best when he 
keeps one cock to two or three hens . 9 Canary-birds 
pair in a state of nature, but the breeders in England 
successfully put one male to four or five females ; never- 
theless the first female, as Mr. Fox has been assured, 
is alone treated as the wife, she and her young ones 
being fed by him ; the others are treated as concubines. 
I have noticed these cases, as it renders it in some 
degree probable that monogamous species, in a state of 
nature, might readily become either temporarily or per- 
manently polygamous. 
9 The Rev. E. S. Dixon, however, speaks positively (‘ Ornamental 
Poultry,’ 1848, p. 76) about the eggs of the guinea-fowl being infertile 
when more than one female is kept with the same male. 
