WHITETHEOAT
sometimes swerving upwards towards a branch in an opposite tree, he momentarily settles upon it, rapidly turns round, and again precipitates himself towards the same spot, and this he may do a few times in succession, always, however, utilising the same branches in the respective trees to settle upon. The whole performance is most peculiar, and gives him a very clumsy appearance, but being so quickly executed it is difficult to describe. How he prevents a collision is surprising, for he often approaches the female so closely that it seems well-nigh impossible for him to swerve away in time.
This peculiar and characteristic flight is performed not only on the first arrival of a female, but occurs throughout the period of sexual activity, though becoming of less and less frequent occurrence as the days pass by. Instances of it can be seen even as late as the latter part of June, and may be due to a recurrence of sexual activity before a second brood. It does not seem to me probable that the male has any direct motive in thus performing, but his actions and his flight, although belonging to the same category as all other weird movements of the wings and body which are common to many species at this period, are so peculiar that they would well merit further investigation. At the same time they are so uniform throughout the species that it is doubtful whether a male could be found which, under the same appropriate circumstances, did not act in a similar manner. The actions of the female give us little or no clue as to whether the performance is distasteful to her, for they could with as much truth be interpreted as expressions of pleasure or disapproval; yet it is not easy to see what pleasure she can possibly derive from it. The same quiet fluttering of the wings which occurs at other periods is often conspicuous, and when the male actually precipitates himself on to her, she receives him as one would expect her to receive an attack; in fact, her method is very similar to the manner in which she does actually receive the attack when fighting with another female; the tail is spread, wings extended, and as he approaches she
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