BRITISH WARBLERS
As the time passes by and sexual activity wanes, so the expression of the emotion subsides, until it finally disappears when the full complement of eggs is laid, except in the case of polygamy or a second brood. Let this, however, be noted, that it is not of uncommon occurrence even after the nest is completed and the first few eggs are deposited. When in the case of adjoining territories a female arrives in one of them while the owner of the other is still unpaired, and when, as is often the case, she is inclined for a while to overstep the boundaries of the territory in which she has settled, the male on to whose ground she wanders becomes excited, and may even commence wing-flapping. I recollect a case of this description which was interesting merely if we regard the actions as of direct biological significance, and as appealing to the female according to the degree in which they are executed, for it was evident that the more demonstrative male was rejected. The female in this particular case wandered from the territory in which she had settled, and from her mate who was showing little excitement, into an adjoining one, and was confronted by the owner who was apparently under the influence of sexual emotion. There she remained for a short time, while he displayed the usual signs of excitement, included in which was considerable and vigorous wing-flapping; eventually she returned to her undemonstrative husband. To such an episode I attach but little importance. The sexual instinct must vary in the same individual from day to day and even from hour to hour, and the corresponding emotion must vary with it. Incidents of this kind are therefore no more than we should anticipate under the circumstances.
Of four adjoining territories, which I had under observation one season, the behaviour of the inmates of one, which I marked as No. 2 on the rough plan made at the time, was so interesting that I offer no apology for describing it in detail, though it entails a repetition of some of the features in the life-history already mentioned. All three territories were situated upon a long wooded bank divided by a public foot-
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