BRITISH WARBLERS
able by selection to breed a race of game-cocks which fight to a finish. Conflicts between the male Willow Warblers on different boundaries are of frequent occurrence, and, at the commencement of the season when two appear to lay claim to the same territory, of some duration, the ruffled feathers denoting the severity of the struggle. At such times their flight is rapid. They pursue one another amongst the bushes, or close to the ground, and when they meet there is an audible clicking of bills and the impact is considerable. To some extent they are oblivious of what is taking place around them, and in their intense eagerness I have seen two combatants pass within a few feet of where I was standing. When they settle, after such encounters, they show signs of considerable excitement, jerking their wings, and giving vent to their feelings by a single or else by a purring note. In the case of males with adjoining territories, the conflicts are not so prolonged, and perhaps on the whole not so severe; they may be better described as incessant quarrels arising from trespass of boundary on the part of some individual. These contests continue for some weeks, but gradually become less and less frequent. From this description I do not wish it to be supposed that a male can never cross its boundary without being attacked, for such is not the case. At the same time I wish it to be clearly understood that, when I speak of a boundary, it is an imaginary one fixed by myself as the result of observation. Nevertheless it is possible to establish with considerable accuracy the true limits of a territory, though these limits may be intruded upon without a conflict occurring.
The second cause of disturbance referred to, namely, the antipathy shown by this species to the presence of a Chiff-chaff—possibly a mutual antipathy—is interesting. It results in frequent quarrels and conflicts, for a pair of each species often inhabit the same territory. Sometimes one is the aggressor, sometimes the other; but the Willow Warbler seems to me to be more often the cause of the strife. The battles resemble those that take place between the males of the same species,
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