BRITISH WARBLERS
tentatively flies or, rather, springs at him, and sometimes they seem to momentarily hold one another by the beak.
I have seen considerable commotion caused by a male Blackcap which, occupying the same territory as a Whitethroat, happened to be paying attention to a female at the same time. Whilst the males were thus pursuing their respective females the four birds often encountered one another in the same bush. Whenever this occurred the male Blackcap exhibited every sign of anger, flying at and vigorously attacking the male Whitethroat, who, as regards strength, was by no means a match for him; and not content only with this attack he would, in his excitement, often imitate the Whitethroat's song.
Assemblies of five or more excited individuals are not of infrequent occurrence, and are very similar to those which we find amongst the Blackcaps. They are not limited to any one sex, but may consist of two females and three males, or two males and two females. The males warble, the females utter their call note, and both sexes show the usual signs of excitement by spreading and waving their tails and erecting their feathers, and although they never go very far distant, but remain more or less in the same locality, yet they move rapidly from tree to tree or along the hedgerows.
The nest is placed in thick undergrowth of some kind, either in the lower parts of tangled hedgerows or in clumps of bramble overgrown with coarse grass, or sometimes in the thick vegetation that grows so luxuriantly in the drier portions of osier beds, no partiality being shown for any one particular herbage. It is usually placed from six inches to three feet from the ground, and is a rather deep but lightly built structure, composed principally of dead grass. But like the nests of many other species the grasses placed at the base are coarser than those used in the interior; wool and pieces of dead thistle are often mixed with the grass, and I have found one nest in which a considerable quantity of cotton-wool had been utilised. The lining, which is of slight thickness, is of horsehair.
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