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.
Such is the nature of the warfare which
