evidence that is required.
Nevertheless, after hearing the whole of the evidence and at the same
time keeping in mind the conclusion which we have already reached, I
venture to think that the close relationship between the warfare on the
one hand and the territory on the other will be fully admitted.

Formerly I deemed the spring rivalry to be the result of accidental
encounters, and I believed that an issue to a struggle was only reached
when one of the combatants succumbed or disappeared from the locality, a
view which neither recognised method nor admitted control. Recent
experience has shown, however, that I was wrong, and that there is a
very definite control over and above that which is supplied by the
physical capabilities of the birds.

Let us take some common species, the Willow-Warbler being our first
example; and, having found three adjoining territories occupied by
unpaired males, let us study the conflicts at each stage in the sexual
life of the three individuals, observing them before females have
arrived upon the scene, again when one or two of the three males have
secured mates, and yet again when all three have paired. Now we shall
find that the conditions which lead up to and which terminate the
conflicts are remarkably alike at each of these periods. A male
intrudes, and the intrusion evokes an immediate display of irritation on
the part of the owner of the territory, who, rapidly uttering its song
and jerking its wings, begins hostilities. Flying towards the intruder,
it attacks viciously, and there follows much fluttering of wings and
snapping or clicking of bills. At one moment the birds are in the
tree-tops, at another in the air, and sometimes even on the ground, and
fighting thus they gradually approach and pass beyond the limits of the
territory. Whereupon a change comes over the scene; the male whose
territory was intruded upon and who all along had displayed such
animosity, betrays no further interest in the conflict--it ceases to
attack, searches around for food, or sings, and slowly makes its way
back towards the centre of the territory.

Scenes of this kind are of almost daily occurrence wherever a species is
so common, or the environment to which it is adapted so limited in
extent, that males are obliged to occupy adjacent ground. The Moor-Hen
abounds on all suitable sheets of water, and it is a bird that can be
conveniently studied because, as a rule, there is nothing, except the
rush