We shall best see the difference between mammals’ and birds’ behaviour by giving some examples. A very strange one I saw in a pond near the Egret rookery in Louisiana. Here, among other interesting birds, were the Darters or Water Turkeys, curious-looking relatives of the Cormorants, with long, thin, flexible neck, tiny head, and sharp beak, who often swim with all the body submerged, showing nothing but the snake-like neck above water. One of these was sitting on a branch of swamp-cedar, solitary and apparently tranquil. But this tranquillity must have been the cloak of boredom. For suddenly the bird, looking restlessly about her (it was a hen), began to pluck at the little green twigs near by. She pulled one off in her beak, and then, tossing her head up, threw it into the air, and with dexterous twist caught it again in her beak as it descended. After five or six successful catches she missed the twig. A comic sideways and downward glance at the twig, falling and fallen, in meditative immobility; and then another twig was broken off, and the same game repeated. She was very clever at catching; the only bird that I have seen come up to her was a Toucan in the Zoo which could catch grapes thrown at apparently any speed. But then the Toucan had been specially trained--and had the advantage of a huge capacity of bill! Here again it might, of course, be said that the catching of twigs is a practice for beak and eye, and helps keep the bird in training for the serious business of catching fish. This is no doubt true; but, as regards the evolution of the habit, I incline strongly to the belief that it must be quite secondary--that the bird, desirous of occupying its restless self in a satisfying way, fell back upon a modification of its everyday activities, just as these are drawn upon in other birds to provide much of the raw material of courtship. There is no evidence that young Darters play at catching twigs as preparation for their fishing, and until there is evidence of this it is simpler to think that the play habit here, instead of being rooted by the utilitarian dictates of natural selection in the behaviour of the species, as with kids or kittens, is a secondary outcome of leisure and restlessness combining to operate with natural aptitude--in other words, true sport, of however simple a kind.