Seite - 40 - in The Origin of Species

40 ORIGIN OF SPECIES sessed the characteristic enormous crop ? The supposed abo- riginal stocks must all have been rock-pigeons, that is, they did not breed or willingly perch 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 improbable; or they must have become extinct in the wild state. But birds breeding on precipices, and good fliers, are unlikely to be exterminated ; and the common rock-pigeon, which has the same habits with the domestic breeds, has not been ex- terminated even on several of the smaller British islets, or on the shores of the Mediterranean. Hence the supposed extermination of so many species having similar habits with the rock-pigeon seems a very rash assumption. Moreover, the several above-named domesticated breeds have been transported to all parts of the world, and, therefore, some of them must have been carried back again into their native country; but not one has become wild or feral, though the dovecot-pigeon, which is the rock-pigeon in a very slightly altered state, has become feral in several places. Again, all recent experience shows that it is difficult to get wild ani- mals to breed freely under domestication; yet on the hy- pothesis of the multiple origin of our pigeons, it must be assumed that at least seven or eight species were so thor- oughly domesticated in ancient times by half-civilised man, as to be quite prolific under confinement. An argument of great weight, and applicable in several other cases, is, that the above-specified breeds, though agree- ing generally with the wild rock-pigeon in constitution, habits, voice, colouring, and in most parts of their structure, yet are certainly highly abnormal in other parts ; we may look in vain through the whole great family of Columbidje for a beak like that of the English carrier, or that of the short-faced tum- bler, or barb ; for reversed feathers like those of the Jacobin ; for a crop like that of the pouter; for tail-feathers like those of the fantail. Hence it must be assumed not only that half-