BRITISH WARBLERS
Can we then regard it as a meaningless habit acquired by a male here and a male there during the few days of bachelor life? Surely not, yet it is difficult to indicate the precise meaning that may be attached to it. Sufficient time can scarcely have elapsed in those few days for a habit of such evident strength to have been formed. Possibly it is not a habit in the sense of something acquired, but rather a congenital endowment common to the race, and let us bear in mind that his behaviour is quite in keeping with that which we can observe in the life of many another species. The disposition to favour some special tree or group of trees within the confines of that which we have called a territory and make of it a headquarters, the eagerness with which it is afterwards sought and made use of, and the reluctance with which it is ultimately yielded to the more pressing matters of reproduction, all point to something more than individual fancy, something definite in fact to be attained, for which racial preparation has probably fitted the birds.
In some cases the period between the arrival of a female in a territory and the commencement of the nest is of remarkably short duration, but whether this is the rule or the exception I cannot say with the records of only a few pairs to rely upon. The female may even commence to build upon the day following her arrival, and one wonders why this should not be the invariable procedure, instead of the procrastination so frequently observed, and of which we really have no explanation. The period of sexual activity is productive of much emotional behaviour, which, though it never reaches the degree of extravagance attained by some species, possesses some interesting features to which attention must be called. The climax of this behaviour is reached, as we should expect, during or just prior to the actual discharge of the sexual function, but I do not mean that the final stage is always reached; there is often excitement on the part of one or of perhaps both sexes which clearly does not materialise, why we do not exactly know. If the completion of the sexual act
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