to
the suggestion that the change can be accounted for by the presence of a
mate, we shall do well to remember not only that males as a rule precede
the females by some days, but that a male may even remain in its
territory, mateless, for some weeks, and yet display hostility.

Nevertheless the case of the migrant did not, by itself, afford
sufficient evidence upon which to base any conclusion. We therefore
inquired into the behaviour of some of the residents at a corresponding
period. The Bunting served as an illustration. Early in the season it
establishes a territory, and because food is then scarce it is forced to
seek it elsewhere than on the small plot of ground which it has
acquired; and so it makes its way to some spot where the supply is
abundant, and there, meeting with other species bent on a similar
errand, forms with them a flock. Part of its time is then spent in the
territory and part on the feeding ground, and between these two points a
highway is formed by the bird passing constantly to and fro. But the
attention which it pays to other species is very different on these two
occasions--when in the territory it is intolerant of strangers, but when
it accompanies the flock it displays no interest in their movements.
From hour to hour its nature seems to change. But, as we saw, the inborn
constitution of the bird cannot change, and therefore we came to the
conclusion that an explanation of the altered behaviour was to be found
in the fact that the pugnacious instinct is only rendered susceptible
under a certain condition. So that all the evidence tended to confirm
the impression which we had gained from the course of events in the life
of the migrant, namely, that the hostility bears a direct relation to
the occupation of a territory.

Finally we were led to inquire whether the hostility was serviceable in
promoting the welfare of the individuals. We saw that many different
species require similar conditions of existence, that ancient breeding
haunts disappear and that new ones come into being, and that in the
ordinary course of events such species must often assemble in the same
area for the purpose of reproduction. So that even though a male might
be successful in protecting its ground from intruders of its own kind,
yet it might still fail to rear offspring, just because it happened to
choose a position in which other kindred forms had gathered. Hence if
the territory is adequately to serve its purpose