Page:Territory in Bird Life by Henry Eliot Howard (London, John Murray edition).djvu/171

Rh between the males is very severe, that large numbers probably fail to pass even this preliminary test, and that only a proportion are in a position to offer to the female the condition under which her process can successfully run its course; so that the presumption is—though it is incapable of demonstration—that there is a competition for such males each recurring season, and that, on the average, the weaker females fail to procreate their kind.

But apart from any direct assistance she may give in driving away intruders, does she in any way help to further the biological end of reproduction? This is a difficult question to answer, and the suggestion I have to make can only apply in those cases in which the territory is occupied throughout the breeding season. Much of the fighting between the males occurs in her presence, and it must be admitted—though it is difficult to speak with any degree of certainty—that such fighting, taken as a whole, bears the stamp of exceptional determination. Let us then grant that the excitement of a male does, under these circumstances, reach a higher level of intensity, and let us see how this will add to the security of the territory. The fact that the male has established itself and obtained a mate is not alone sufficient to accomplish the end for which the territory has been evolved. During the period between the initial discharge of the Sexual function and the time when incubation draws to a close, much may happen to prejudice the future of the offspring; there