s, all swimming about
together, and, if the pool is surrounded by arable land, wandering over
that land subject to no territorial restrictions, apparently free to
seek food where they will. But as time goes by, their number gradually
decreases until a few pairs only remain, and these will occupy definite
areas. If careful watch is then kept and the relations of the pairs
closely studied, there will be no difficulty in observing the particular
kind of warfare to which I am alluding, and it will be noticed that the
encounters are of a particularly violent description. Thus two pairs
approach one another, and, when they meet, throw themselves upon their
backs, each bird striking at its adversary with its feet or seizing hold
of it with its beak; and though, in the commotion that ensues, it is
almost impossible to determine what exactly is happening, there is
reason to believe that the sexes attack one another indiscriminately.

A struggle between two pairs of Pied Wagtails is worth mentioning. It
impressed itself upon my memory because of the unusual vigour with which
it was conducted. The battle lasted for fifteen minutes or more, and
the four birds, collecting together, pursued and attacked one
another--at one moment in the air, at another upon the roof of a house
where they would alight and flutter about on the slates, uttering their
call-note without ceasing--until finally they disappeared from view,
still, however, continuing the struggle.

[Illustration: Two pairs of Pied Wagtails fighting in defence of their
territories.

Emery Walker ph.sc.]

Such is the nature of the warfare which prevails between neighbouring
pairs, and which can be observed in the life of many other species--the
Chaffinch, Stonechat, Blackbird, Partridge, Jay, to mention but a few.

The conflicts between males that are definitely paired are of such
common occurrence that it is scarcely necessary to mention specific
instances. But the occasions on which a male attacks either sex of a
neighbouring pair indiscriminately, or on which a pair combine to attack
a female, are less frequent.

Now if it be true that males fight for no other purpose than to gain
possession of a mate, what meaning are we to attach to the battles
between the pairs, or what explanation are we to give of the fact that
paired males are so frequently hostile? Those who hold this view will
probably argue thus: "The presence of the female is the condition under
which the pu