Page:The British Warblers A History with Problems of Their Lives - 2 of 9.djvu/35

 is especially striking; sitting in a very upright position he raises the feathers on his head and back, the latter being thus much rounded, throws his breast feathers forward, swells out his throat, carries his wings rather loosely, giving himself the appearance of a round ball of feathers, spreads out his tail as far as possible and moves it sideways very slowly; this latter feature is curious, for he never at other times moves his tail in this way, herein differing from such birds as the Red-backed Shrike (Lanius collurio) and Redstart (Ruticilla phœnicurus), who habitually make use of this side-long motion when excited.

During the period of courtship the males are apparently very quarrelsome, but the possession of the female does not appear to be the direct cause of their battles; perhaps they are not battles but only games; this is most difficult to decide, for they are frequently so vigorous that the impression left on one's mind after watching them is that of a severe fight. Their flight when pursuing one another is very quick, entirely different from their ordinary one, and the way they dart in and out of the trees is quite amazing, the pursuing male as he flies often uttering the two notes, of which his song is composed, very quickly; and at other times both pursuer and pursued use the same buzzing note as during the courtship. The actual fight generally takes place in the air, the clicking of their bills as they meet one another being quite loud. When standing close to them during these struggles they have sometimes fallen within a few feet of me, and as they tumble, locked together, through the air, twisting slowly round and round, they look like a mass of feathers devoid of all form; upon reaching the ground they lie for a few seconds exhausted or surprised, then fly quietly away, each in his own direction.

Nidification commences about the middle of April, soon after the courtship has taken place. The exact time varies, and the rapidity with which the nest is built varies correspondingly with it; sometimes the nest is commenced in a lazy