BRITISH WARBLERS 
territories work their way towards the same boundary simul- 
taneously. As they approach the boundary the song becomes 
more frequent and very hurried, their whole attitude being 
one of great excitement. As they approach still more closely, 
this excitement increases, their wings are jerked about, the 
song deteriorates into a few notes rapidly uttered, they still 
pretend to hunt for food in a half-hearted sort of manner, but 
all the time it is evident that each one is keeping a close watch 
upon the other’s movements: then the climax is reached, they 
dart at one another, tumbling over and over in the air, their 
bills clicking loudly; and, their honour appearing to be 
satisfied, they immediately retire to their respective territories. 
The final scene is not, however, always reached, for just 
as the excitement seems to be at its highest point, one of 
them commences to move in the opposite direction. Where- 
ever there are territories adjoining, this scene, or a scene 
similar to what I have described, is of common occurrence, 
frequently being enacted by the same individuals many times 
during the same morning. 
Whether these scenes are prompted by pugnacity or 
whether they are simply due to love of play I cannot tell, 
but there is most probably some relation between them and 
the importance to each individual of his respective territory. 
As their behaviour shows, each one is undoubtedly conscious 
of the approach of his rival for some distance before the 
boundary is reached. Whether the fight or game only takes 
place when one actually crosses the boundary I have not 
been able to determine. 
A male that has recently arrived often passes through 
the territory already adopted by some earlier arrival, and his 
behaviour under these circumstances is instructive. He creeps 
amongst the bushes low down, almost in the undergrowth, 
not singing, but occasionally uttermg a note, apparently 
anxious to keep out of sight. It is, however, seldom that 
he remains long undetected by the keen eye of the owner, 
who immediately starts in pursuit, darting after him with 
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