Nor does it rise just in front of the other bird; but swims under and just beyond, and, as its mate swings round to the new orientation, emerges in a really extraordinary attitude. At the last it must have dived a little deeper; for now it appears perpendicularly from the water, with a slowish motion, slightly spiral, the beak and head pressed down along the front of the neck. I compared it in my notes of ten years ago with “the ghost of a Penguin,” and that comparison is still the best I can think of to give some idea of the strange unreality of its appearance. It then settles down upon the water and the pair indulge in one of their never-failing bouts of head-shaking. Two mated birds rejoin each other after a few hours’ separation. Simple enough in itself--but what elaboration of detail, what piling on of little excitements, what purveying of thrills! Other emotions too can be well studied in this bird, notably jealousy. Several times I have seen little scenes like the following enacted. A pair is floating idly side by side, necks drawn right down so that the head rests on the centre of the back. One--generally, I must admit, it has been the cock, but I think the hen may do so too on occasion--rouses himself from the pleasant lethargy, swims up to his mate, places himself in front of her, and gives a definite, if repressed, shake of the head. It is an obvious sign of his desire to “have a bit of fun”--to go through with one of those bouts of display and head-shaking in which pleasurable emotion clearly reaches its highest level in the birds’ lives, as any one who has watched their habits with any thoroughness would agree. It also acts, by a simple extension of function, as an informative symbol. The other bird knows what is meant; it raises its head from beneath its wing, gives a sleepy, barely discernible shake--and replaces the head. In so doing it puts back the possibility of the ceremony and the thrill into its slumbers; for it takes two to make love, for Grebe as for human. The cock swims off; but he has a restless air, and in a minute or so is back again, and the same series of events is run through. This may be repeated three or four times. If now another hen bird, unaccompanied by a mate, reveals herself to the eye of the restless and disappointed cock, he will make for her and try the same insinuating informative head-shake on her; and, in the cases that I have seen, she has responded, and a bout of shaking has begun. Flirtation--illicit love, if you will; for the Grebe, during each breeding season at least, is strictly monogamous, and the whole economics of its family life, if I may use the expression, are based on the co-operation of male and female in incubation and the feeding and care of the young. On the other hand, how natural and how human! and how harmless--for there is no evidence that the pretty thrills of the head-shaking display ever lead on to anything more serious.