The different response a territorial animal (see territoriality) makes to an intruder that it recognizes compared with the response evoked by a stranger. When a stranger manages to establish a territory, at first there will be countless border disputes with holders of adjoining territories. After a time, however, the newcomer becomes established and recognized by neighbours. Then, when the newcomer intrudes on to a neighbouring territory, its occupant will make a shorter threatening run than it would to a complete stranger and if it gives chase the chase will be shorter. This saves the defender time and energy and succeeds because if the intruder should drive out the occupant it would then face border disputes with all the neighbours that regarded it as a stranger, so it accepts the agreed definition of the borders and acknowledges its mistake by retreating.
Subjects: Ecology and Conservation.