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.

[Illustration: 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 c