A friend of mine who knows the Welsh mountains and is a watcher of birds as well, tells me that he has there seen the Peregrine Falcons do the same thing: the same thing--except that the speed was perhaps twice as great, and the background a savage rock precipice instead of a Berkshire garden. Not only the activities of everyday life, but also those of nest-building, are taken and used to build up the ceremonies of courtship; but whereas in the former case the actions are simply those which are most natural to and best performed by the bird, in the latter there is, no doubt, actual association between the cerebral centres concerned with nest-building and with sexual emotion in general. Thus we almost invariably find the seizing of nest-material in the beak as a part of courtship, and this is often extended to a presentation of the material to the mate. This we see in the Grebes, with the dank weeds of which their sodden nest is built; the Divers use moss in the construction of theirs, and the mated birds repair to moss banks, where they nervously pluck the moss, only to drop it again or throw it over their shoulder. Among the Warblers, the males pluck or pick up a leaf or twig, and with this in their beak hop and display before the hens; and the Peewit plucks frenziedly at grass and straws. The Adelie Penguins, so well described by Dr. Levick, make their nests of stones, and use stones in their courtship. A curious, unnatural transference of object may sometimes be seen in these Penguins. The normal course of things is for this brave but comic creature, having picked up a stone in its beak, to come up before another of opposite sex, and, with stiff bow and absurdly outstretched flippers, to deposit it at the other’s feet. When, however, there are men near the rookery, the birds will sometimes in all solemnity come up to them with their stone offering and lay it at the feet of the embarrassed or amused human being. The Adelies do not nest by their natural element the sea, but some way away from it on stony slopes and rock patches; thus they cannot employ their brilliant dives and feats of swimming in courtship, but content themselves, apart from this presentation of household material, with what Dr. Levick describes as “going into ecstasy”--spreading their flippers sideways, raising their head quite straight upwards, and emitting a low humming sound. This a bird may do when alone, or the two birds of a pair may make a duet of it. In any case, the term applied to it by its observer well indicates the state of emotion which it suggests and no doubt expresses.