BRITISH WARBLERS
time to time have been suggested by those who have given thought to the problem. Now this theory in all its interpretations has but one end in view, namely, that the fitter individuals shall attain to reproduction; and inasmuch as the struggle for territory makes towards a similar goal, it is a matter of some difficulty to assign a place to both in the drama of bird life. Therefore when discussing the theory of breeding territory in the life of the Reed Warbler, I gave my reasons for attributing to those battles, which precede reproduction, the elimination of the weaker individuals. Frequent, however, as these struggles are, much as they appeal to our imagination, yet there is no gainsaying the fact that in each season a proportion of both males and females will escape the necessity for a struggle; and just in so far as the unfit elude its meshes the sieve may be said to be imperfect in operation. Here the advocates of an emotional test will doubtless take their stand; a second ordeal, they will say, must be all to the good, ensuring, as it will, a more complete elimination of the unfit. This second test must be complementary, not antagonistic to the first, otherwise the securing of a territory will ensure nothing; it must operate not on those wanderers with no settled home, nor on the victims of many struggles, but on the weaker members who without being challenged have become possessed of territories and thus undeservedly qualified to propagate their kind. If this be really true, it is manifest that each season there must be a certain proportion of males who, though possessing territories, are nevertheless doomed to remain without a mate. My experience does not bear this out. No single instance of a male possessing a territory and yet failing to attain to reproduction has ever come to my knowledge; and of all the objections to a second test, this is perhaps the most serious. We must therefore wait before unreservedly accepting it, until we are in possession of a body of observations serving to show that the securing of a territory does not suffice to ensure the attainment of reproduction; and such observa-
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