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 extravagance 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 Blackcap, 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
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