VARIATION UNDER DOMESTICATION If 



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, and in some breeds the 

 voice and disposition, differ remarkably. Lastly, in certain breeds, 

 the males and females have come to differ in 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 be ranked by him as well-defined species. 

 Moreover, I do not believe that any ornithologist would in this 

 case place 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 would call them, could be shown him. 



Great as are the differences between the breeds of the pigeon, I 

 am fully convinced that the common opinion of naturalists is cor- 

 rect, namely, that all are descended from the rock-pigeon (Col- 

 umba livia), including under this term several geographical races or 

 sub-species, which differ from each other in the most trifling re- 

 spects. 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 charac- 

 teristic enormous crop? The supposed aboriginal 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 flyers, are unlikely to be exterminated; and the common 

 rock-pigeon, which has the same habits with the domestic breeds, 

 has not been exterminated 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 



