ly
determined by the impulse to seek isolation. As individuals of
different species establish themselves, and form kingdoms and lesser
kingdoms, we can watch the gradual quickening into life of moorland and
forest and we can observe the manner in which it all comes to pass.
Males that for weeks or months have lived in society, drifting from
locality to locality according to the abundance of food or its scarcity,
now set forth alone and settle first here and then there in search of
isolation. Lapwings settle in the water meadows, and, finding themselves
forestalled, pass on in search of other ground; Blackbirds arrive in a
coppice or in a hedgerow and, meeting with opposition, disappear; and
the Curlew, wandering with no fixed abode but apparently with a fixity
of purpose, searches out the moorland where it can find the particular
environmental conditions to which its inherited nature will respond. In
fact, wherever we choose to look, we can observe in a general way the
gradual appropriation of breeding ground; and if we fix our attention
upon particular males, we can watch the method by which success or
failure is achieved.

On more than one occasion I have watched the efforts of Reed-Buntings to
appropriate territories in a marsh that was already inhabited. Sometimes
their efforts met with success, at other times with failure. In the
former case, the males, whose ground was intruded upon, were severally
forced to yield part of their holding and were thus left in possession
of a smaller area. The success of the intruder seemed to depend upon
persistent determination, rather than upon superior skill in battle.
Recently I had an opportunity of observing the intrusion of a male
Willow-Warbler upon ground already occupied. By persistent effort it
succeeded in appropriating one half of the territory of its rival. The
intruder occupied some trees on the outskirts of the territory it was
invading, and used them as a base from which it made repeated efforts to
enter the ground of its rival. These efforts were time after time
frustrated. No sooner did it leave its base than it was seen and
intercepted, or else attacked; and no matter from which direction it
attempted to effect an entrance, its efforts, for a time, were all to no
purpose. The fighting was of a determined character, and after each
attack the owner of the territory showed signs of great excitement, and,
sitting upright upon a branch, spread and waved its wings, whi