BRITISH WARBLERS 



those peculiar vocal extravagances in which the Blackcap 

 is liable to indulge under similar circumstances. This 

 disturbance attracts the attention of surrounding species; 

 Blackcaps approach the scene spreading their tails and 

 uttering their call note, Whitethroats flit about adding to 

 the commotion, and an inquisitive Chiff-chaff frequently 

 puts in an appearance. A confused medley of sounds is 

 thus produced and it is usually some minutes before quiet 

 is again restored. Assemblies of males sometimes occur, but 

 less frequently, I think, than in the case of the Blackcap. 

 What the cause of such assemblies may be I cannot tell ; 

 the sexual instinct is no doubt responsible in a great measure, 

 but further observation is required to trace out the true 

 meaning. We can only speak with certainty touching the 

 general resemblance of the behaviour to that of the Blackcap 

 under similar circumstances. 



The period of sexual activity is productive of much 

 extravagance in their behaviour. Peculiar attitudes are 

 assumed and antics indulged in, the majority of which can be 

 observed with little difficulty, but the degree of extrava- 

 gance usual in the case of the Blackcap is not attained; 

 the distinct types of attitude are less numerous, though 

 perhaps marked by greater definiteness. In the Black- 

 cap, however, we are taking as a comparison a relatively 

 high level of emotional manifestation, and it is well to bear 

 this in mind. The motor reactions during sexual activity 

 take diversities of form in different species ; the wings, tail, 

 and feathers generally are made use of in numerous fashions, 

 yet it is doubtful whether we can speak of any one as 

 exclusively characteristic of this or that species. Indeed it is 

 astonishing how often we find a similar behaviour-response 

 indulged in by widely separate species. A good illustration 

 of this is a performance of the Garden Warbler, which is 

 remarkable for its beauty, and may be likened in some respects 

 to the fluttering of a large moth. Perched upon a branch the 

 bird spreads its tail, flutters its wings so rapidly that the 



