GRASSHOPPER-WARBLER
running, or flying away from her suitor—indeed. I cannot call to mind a single instance in which I have, even for a brief moment, seen the female looking at the male while assuming these positions—and therefore has her back turned to him when we ought to expect her to be examining the details of his plumage. It might be here argued that for the female to get the general effect of the male's display would, through such immense periods of time, be sufficient to account for the beauty of the plumage; but I cannot bring myself to believe, even if the other and more weighty objections could be removed, that such a casual inspection could be the means of developing minute and beautiful patterns, the very delicacy of which must surely cause us all to marvel. This, however, we know, that as a bird grows older the colours of the plumage become intensified, and even the plumage itself becomes finer in quality, and amongst the Warblers this difference is so marked as to at once arrest attention. He, then, who supports the principle of selection must admit that the older males being more richly coloured would be first selected; he must also admit that the offspring of these more successful males could inherit no advantage, inasmuch as the success of their parents was due solely to laws of continuous growth.
"Early in July a courtship, similar in every respect to the one in spring, occurs amongst the Sedge-Warblers."
Admitting the principle of selection, we must nolens volens assume this to be a selection taking place before the second brood, conclusively proving the choice of the female in the first instance to have been a mistake.
"The ultimate production of the most healthy and most beautiful offspring by the selection of certain males is, without a corresponding selection amongst the females, impossible, and of the existence of such selection in any form there is no evidence."
Individuals of both sexes vary very considerably both in intensity of colouring and actual quality of plumage. As an
15
