Page:The British Warblers A History with Problems of Their Lives - 7 of 9.djvu/65

 away from the nest of the latter bird. As usually happens, the Sedge Warbler was most pugnacious and resented the presence of other species, especially in the one particular tree. The burden of his anger generally fell upon the Marsh Warblers, and no discrimination was made between the sexes, both male and female being frequently attacked and pursued. The Marsh Warbler as a species is not of a very peaceable disposition, and the result of this was that for some days at least that particular corner of the osier bed was in constant commotion. The Sedge Warbler was undoubtedly more often the aggressor, pursuing his opponents this way and that in the territory, and judging by their frequent retreats the Marsh Warblers must have been afraid of him. Yet at times one or the other, or perhaps both, made some show of resistance. Most of the skirmishing occurred in the special willow, and in fact seemed to originate in the Sedge Warbler's jealousy of that particular tree. Occasionally the quarrel ended in the refusal of the Marsh Warbler to retire from his headquarters, for spreading his tail he would scold vigorously at his opponents only a few feet away. Even after he had obtained a female the Sedge Warbler still maintained his pugnacious attitude, though perhaps in a lesser degree.

The period of sexual activity no doubt varies in the case of different individual pairs according to the early or late arrival of the female, and possibly according to her physical condition. I have not had opportunities of studying a sufficient number of pairs to make a correct estimate of the average duration of this period possible, but according to my experience hitherto it would seem to be approximately eight days. Still more difficult is it to state with any degree of accuracy how long after her arrival the female actually commences to construct her nest, but in some cases a commencement is made on the following day. In attempting, however, to estimate either of these periods one might easily be deceived. The female is at all times more skulking in her habits than the male. She creeps amongst the dense