s become a maroon bird." The common duck wanders from its
home and becomes almost wild in Norfolk. Hybrids between the common and
musk-duck which have become wild have been shot in North America, Belgium,
and near the Caspian Sea. The goose is said to have run wild in La Plata.
The common dovecot-pigeon has become wild at Juan Fernandez, Norfolk
Island, Ascension, probably at Madeira, on the shores of Scotland, and, as
is asserted, on the banks of the Hudson in North America.[333] But how
different is the case, when we turn {191} to the eleven chief domestic
races of the pigeon, which are supposed by some authors to be descended
from so many distinct species! no one has ever pretended that any one of
these races has been found wild in any quarter of the world; yet they have
been transported to all countries, and some of them must have been carried
back to their native homes. On the view that all the races are the product
of variation, we can understand why they have not become feral, for the
great amount of modification which they have undergone shows how long and
how thoroughly they have been domesticated; and this would unfit them for a
wild life.

_Fourthly._--If it be assumed that the characteristic differences between
the various domestic races are due to descent from several aboriginal
species, we must conclude that man chose for domestication in ancient
times, either intentionally or by chance, a most abnormal set of pigeons;
for that species resembling such birds as pouters, fantails, carriers,
barbs, short-faced tumblers, turbits, &c., would be in the highest degree
abnormal, as compared with all the existing members of the great
pigeon-family, cannot be doubted. Thus we should have to believe that man
not only formerly succeeded in thoroughly domesticating several highly
abnormal species, but that these same species have since all become
extinct, or are at least now unknown. This double accident is so extremely
improbable that the assumed existence of so many abnormal species would
require to be supported by the strongest evidence. On the other hand, if
all the races are descended from _C. livia_, we can understand, as will
hereafter be more fully explained, how any slight deviation in structure
which first appeared would continually be augmented by the preservation of
the most strongly marked individuals; and as the power of selection would
be applied according to man's fancy, and not for the bird's own good, t