86 DISPOSITION TO DEFEND THE TERRITORY 



swimming about together, and, if the pool is 

 surrounded by arable land, wandering over that 

 land subject to no territorial restrictions, appar- 

 ently 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 descrip- 

 tion. 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 Wag- 

 tails 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, con- 

 tinuing the struggle. 



Such is the nature of the warfare which 



