really want or mean—may be accounted for. As the season advances, the tendency will be more and more for the two birds (but I here speak of birds generally) to avoid, or actively to drive away, the third, and for the third to find another bird for a partner, the whole being tempered by the character both of the species of bird and the individual birds belonging to it. The three birds being thus brought together, without the feelings being of a very strong or defined character, and the feelings of animals generally being, as I believe they are, of a very plastic nature (by which I mean that they pass easily from one channel into another), I can understand a sort of sport or game of three birds together arising, at first almost imperceptible, till, by the fundamental laws of evolution—variation and inheritance—it might pass into something highly peculiar, as in the case of the spur-winged lapwing—for though such sport might commence in the air, there would be no reason why it should not pass from thence on to the ground. And that the number should be three, and not more, is thus also explained, for whilst the sight of a paired male and female bird would be likely to excite the sexual feelings—even though, as here supposed, somewhat languid—of another male, so as to make it join them, three together would hardly have this effect in an equal degree, and, moreover, more than three would tend to become a flock, when other feelings would come into play. However this may be, I have, as a matter of fact, been struck with the frequency with which, in the early spring, three birds will keep together, as and in the manner before stated."
This, it will be observed, was written at a time of
