Swans
The swan, like the peacock, has been bred for ornament rather than for use. In fact, the bird has no other merit than its exceeding grace. We cannot believe that much pains was ever taken with this creature to break up the migratory instincts which are common in the wild kindred species. We have to suppose that the bird in its pristine form was without the impulse to undertake distant journeys in the winter season, or that it abandoned ancient habits with no great difficulty. We obtain some light on this point by noting the fact that among the migratory species it not infrequently happens that, while the greater number of individuals undertake the annual journey, certain of them will remain on the ground where they were born. Those which remain would be more likely to mate with those which were like-minded than with others that journeyed afar. In this way small local breeds might well be originated which would differ from their migratory kindred not only in the measure of the wandering instincts, but in the capacity for flight which their kindred preserve. There is some reason to believe that this process of selection naturally and somewhat frequently takes place. In certain cases it may lay the foundation of new species, or at least of distinct varieties; more commonly, however, the individuals which have abandoned the migratory life are likely to perish from the severity of climate or the other unfavorable conditions that their mates avoid by their wanderings.
The Original Wild Rock Dove (Columba livia)
and Some of its Domestic Descendants
Although many of the free-flying birds of the land are or have been kept captive because of the pleasure which men have found from their songs, their grace, or their quaint ways, only one of these has really been gained to domestication. In the pigeon, man has made what is on many accounts the most remarkable of all his conquests over the wild nature about him. While the breeder's art has led many forms, some of them on several divergent lines, far away from their primitive estate, in no other field has it accomplished such surprising results as with the doves. The original wild form of this group is a native of Europe and Asia, where the species Columba livia, or rock pigeon, is still common, and whence it may be readily won anew to domestication. It is a small, plain-colored, rather invariable and inconspicuous bird about the size of our American dove. In its wild state it dwells in small flocks, nesting by preference in the crannies of the cliffs, and exhibiting no striking qualities which make it seem a desirable subject for domestication. We note, however, that even in this primitive condition the creature has certain physical and mental qualities which have been the basis of its adoption by man as well as of the wide changes which it has undergone at his hands.
It is a characteristic of all the doves that their young are born in a very immature state, and for some time after they come from the egg they have to be supplied with food which has been partly digested in the crop or upper part of the stomach of the parent. For the proper rearing of the brood there is required the assiduous care of both parents. Therefore quite naturally we find among these birds that the pairing habit is well developed, and as they rear several broods each season, that the mating is for life. Although there are numbers of birds in various orders which are accustomed to the monogamic habit, it happens that the pigeon is the only animal which man has ever won to true domestication in which the sexes can be thus permanently united. In the dovecote, however many birds it may contain, the breeder can be always sure as to the parentage of the young which he is rearing. This affords an admirable basis for the practice of his art, which is still further favored by the fact that pigeons reproduce rapidly and the progeny are ready to mate in a few months after they come into the world. Thus the species affords really ideal conditions for that process of selection on which the improvement of all domesticated animals intimately depends.
