Page:The British Warblers A History with Problems of Their Lives - 3 of 9.djvu/51

 there is a harsh cry from a distant male, and this is sufficient to arouse their passions. It seems as if very little inducement was necessary to prolong this excitement when once aroused. The males collect from adjoining territories, often some distance from where their mates are sitting, and though they seem to assemble more or less in the same place, yet it is difficult to make certain of this, since they move about very considerably. I have, however, noticed that such assemblies occur frequently in the territory of a certain male, while only rarely in that of others adjoining. A male, while incubating, will suddenly leave his nest and dart off to join one of these assemblies, or intrude upon a later pair during their courtship. In the latter case, all three birds become very excited, the males spread their tails, extend their wings, and flap through the air, and the female raises her feathers and screams. The male that is courting undoubtedly resents the presence of the other, for he will attack him, and while doing so will fluff out the feathers on his breast and back, erect his head feathers, and spread out his tail. Whether these assemblies are prompted by a love of play, jealousy, anger, excitement only, or some cause of which we are not at present cognisant, remains a subject for speculation. The direct stimulus is often quite apparent, and this, in most cases, is the presence of a female. It is during the first few hours of the morning, when the females of most species leave their nests, that coition takes place, and I am inclined to think that this is often the cause of the excitement; but it is clear that it is not always so, as, for instance, when the males collect round a member of some other species; though even here sexual passion may be indirectly the cause. The excitement diminishes in intensity week by week, finally disappearing when the young are reared and the males leave their breeding territories.

Sometimes when a pair are quietly feeding amongst the oaks, a second male joins them, an intrusion to which the other male objects, spreading out his tail; on the arrival of