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
