relative length of leg and of the feet; the number of scutell on the
toes, the development of skin between the toes, are all points of
structure which are variable. The period at which the perfect plumage
is acquired varies, as does the state of the down with which the
nestling birds are clothed when hatched. The shape and size of the eggs
vary. The manner of flight differs remarkably; as does in some breeds
the voice and disposition. Lastly, in certain breeds, the males and
females have come to differ to a slight degree from each other.
Altogether at least a score of pigeons might be chosen, which if shown
to an ornithologist, and he were told that they were wild birds, would
certainly, I think, be ranked by him as well-defined species. Moreover,
I do not believe that any ornithologist would place touch; the
oil-gland is quite aborted. Several other less distinct breeds might
have been specified.
the English carrier, the short-faced tumbler, the runt, the barb,
pouter, and fantail in the same genus; more especially as in each of
these breeds several truly-inherited sub-breeds, or species as he might
have called them, could be shown him.
Great as the differences are between the breeds of pigeons, I am fully
convinced that the common opinion of naturalists is correct, namely,
that all have descended from the rock-pigeon (Columba livia), including
under this term several geographical races or sub-species, which differ
from each other in the most trifling respects. As several of the
reasons which have led me to this belief are in some degree applicable
in other cases, I will here briefly give them. If the several breeds
are not varieties, and have not proceeded from the rock-pigeon, they
must have descended from at least seven or eight aboriginal stocks; for
it is impossible to make the present domestic breeds by the crossing of
any lesser number: how, for instance, could a pouter be produced by
crossing two breeds unless one of the parent-stocks possessed the
characteristic enormous crop? The supposed aboriginal stocks must all
have been rock-pigeons, that is, not breeding or willingly perching on
trees. But besides C. livia, with its geographical sub-species, only
two or three other species of rock-pigeons are known; and these have
not any of the characters of the domestic breeds. Hence the supposed
aboriginal stocks must either still exist in the countries where they
were originally domesticated, and yet be unknown to ornithologists; and
this, considering their size, habits, and remarkable characters, seems
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