BLACKCAP
intensity of this excitement and the length of time that the male has been previously absent from the female; for I have noticed that, amongst the majority of the migratory species, the excitement, as evinced by their actions, is much greater than the average excitement displayed at the corresponding period amongst resident species. In this respect it is almost possible to trace a distinct gradation, commencing with those species that pair for life—in which case the excitement is limited to the time immediately preceding coition—up to the migrants, which represent the highest type of such excitement. That there should be such gradations can be readily understood if it is accepted that all the special activities of this period are directly caused by the development and stimulation of the sexual organs; for resident species probably pair before such development has taken place, consequently the natural passion can be immediately relieved; this is also the case with species that pair for life, but amongst the migrants the conditions are very different, for the males, as a rule, arrive before the females, and being sexually developed, are excitable and possessed of great energy, which reaches its height only on the appearance of the female. A study of the males from this point of view is interesting and, to myself, very convincing. I am, therefore, inclined to doubt whether the term "courtship" is really admissible, whether, in fact, an altogether erroneous impression is not thereby conveyed. And, as bearing on this question, it is a fact of no small importance that the males generally pair with the females that first settle in their territory, before whom they have behaved in the manner referred to, and ultimately rear with them offspring in that territory.
It is difficult to describe the excitement of the male when a female is present; the variations in the sounds he produces and the antics he performs are so numerous. The intensity of his emotions soon discloses the fact that a female has arrived, and it is then no difficult matter to approach him closely, the more so as he is never very far distant from
11
