some spontaneous Variations in Mallard & Muscovy Ducks. 107


A similar case is furnished by the Andaman Teal (Nettium

albigulare ) all recently captured specimens of which I have seen

show a white head (except for the crown and a few scattered

feathers) and nape, in both sexes ; yet such birds breed young whose

heads are at first without white, and have only a white eye-ring

developed at first, as the normal bird used to have. Here we have a

character suddenly developing in an undomesticated bird.


The variations of the two domesticated ducks also throw

light on the phenomena of “warning colours” and “mimicry.”

They are not at all nearly allied, and the Muscovy is much the more

able to look after itself, and is inferior, as human food, to the

common duck.


Hence its conspicuous colour and slow flight (the half-wild

birds bred in the Zoo showed this well) would be put down as

characteristics of a protected ” species if it were an insect. These

characteristics are enhanced in domestication by the general change

of the black of the male’s bare face to red, the common appearance

of abnormal white in the plumage, and the frequently yellow (instead

of dark) colour of the feet.


At the same time, the common domestic duck, the descendant

of the very different-coloured and far more palatable and helpless

Mallard, often varies from its normal colouration to resemble the

Muscovy, for one often sees black-and-white common ducks coloured

and marked very like pied Muscovys. Moreover, white and blue-grey

forms of both occur. Yet no one would conclude that the tame

Mallard is developing their colours by selection, individuals having

colours like Muscovys having escaped the clutches of the poulterer

thereby ! Thus we need not conclude that if two remotely related

species of butterflies or birds in the same district resemble each

other that natural selection has brought this about.


Finally, we may learn a lesson as to the development of sex-

colouration. I have cited an instance in which the development of

the blue-grey colouration in the Muscovy showed a tendency to be

limited to the males; if this proved hereditary we could soon raise a

strain characterized by blue-grey males and black females, and this

would not have been due to the “preference of the females through

untold generations,” but to an abrupt unexplained development of a



