Page:The British Warblers A History with Problems of Their Lives - 7 of 9.djvu/47

 Warblers vary considerably. I have sometimes been impressed with the remarkably small area which is embraced, fifteen square yards in one instance being almost sufficient to enclose the wanderings of the male. So small an area is noteworthy when compared with that of other species living in a similar environment. However. I am not in possession of the daily records of a sufficient number of pairs to justify any very definite conclusion upon this point. Nevertheless if at some earlier period the bird had been an inhabitant of reed beds, building its nest therein, the dimensions of its territory must necessarily have been small, as in the case of the Reed Warbler; and although these dimensions would certainly have been gradually modified to suit the new environment, yet a reversion in certain cases to the former conditions would be neither impossible nor unlikely, especially if the change had been of comparatively recent occurrence.

Before the arrival of a female, the male will be found to be constantly moving around his territory, and if his wanderings are carefully watched, it will be seen that they are not quite so aimless as they may at first appear, but subject to some routine. A certain tree or bush is selected and regarded as a favourite resort. From this tree excursions are made into different parts of the territory, but even these excursions bear evident traces of that tendency towards routine so common in animal life, for the short journeys are often made in the same direction, the same bushes are selected and forced to give up part of their stock of insect life, and then only is a return made to the tree more especially favoured. In having a headquarters, therefore, the bird resembles the Reed Warbler, and for the matter of that many other species too. Various trees are made use of for this purpose, alders, willows, or even clumps of tall decayed vegetation; and previous to the arrival of a female more time is spent in this one spot than in the remainder of the territory, and of that time a considerable portion is passed in the exercise of those vocal masterpieces in which the bird excels.