the displays in question may be due to it simply and solely: but I cannot believe that all are. Why should this be the case, or how can movements which are often of a complex and elaborate nature be explained solely by reference to some large general factor, such as joy or vital energy? These may lie at the root of all; but something else, some more special process is, I think, in many cases required. One would not be content to explain all the phenomena of history by a reference to human nature, and though it may be true, as the Kaffirs say, that in a cattle-kraal there can only be one bull, yet nature is a good deal larger than a cattle-kraal. I believe myself that various antics which are performed by birds have grown out of various nervous, excited, or automatic movements arising under the influence of various special causes. Two such possible causes—viz. (i) sudden alarm whilst incubating, and (2) paroxysms of rage or nervous excitement during rivalry for the female I have already indicated. Two other possible ones have also been suggested to me by some of my observations, and I will now, by the aid of these, make an attempt—I daresay a lame one—to throw light on the possible origin of a very extraordinary case of bird-antics, described by Mr Hudson in the work I have mentioned, and which is believed by him to be unique.
The bird in question is the spur-winged lapwing, and the following is Mr Hudson's account of its performances:—
"If a person watches any two birds for some time—for they live in pairs—he will see another lapwing, one of a neighbouring couple, rise up and fly to them,
