Page:The British Warblers A History with Problems of Their Lives - 9 of 9.djvu/33

 determined in part by acquired experience, though founded on a congenital basis. Now this theory of breeding territory raises questions of some importance. It is closely related to the law of battle so firmly established by Darwin, but differs from it in one important particular, namely, that the struggles have their primary origin in an impulse to acquire a territory rather than in one to acquire a female. Concerning the existence of battles in animal life during the period of reproduction there are no two opinions; nowhere are they more noticeable than in the sexual life of birds, and the facts which will be found in the foregoing pages concerning them add nothing new materially, though they serve to confirm our previous knowledge of the subject, already fairly comprehensive. It is in regard to the meaning of such struggles that opinion is so divided. Is a female or a territory the primary cause of disturbance? In the life histories of eleven of the more common forms dealt with, will be found evidence, greater or less, of the disposition to secure a territory, and in most cases it will be observed that the male settles in a small area of ground, there awaits a female, and there remains so long as the young require care: and that far from remaining a passive onlooker at any intrusion he actively repels the approach of a stranger. Conflicts also occur even before the appearance of a female upon the scene. Reference is made to these initial struggles in the histories of the Willow Warbler, Wood Warbler, Blackcap and Marsh Warbler. They demand our careful consideration, since the absence of the female compels us to look elsewhere than in her direction for the primary factor in the dispute. If indeed they were of rare occurrence—a casual struggle here or there—if they bore no trace of persistent striving towards some biological end, and if they were in no way related to the movements of the male in the few acres which he has occupied as a territory, one might perhaps argue that individuals who occasionally exercised just those qualities requisite for obtaining the female when she did at length arrive would by so doing gain some slight