No doubt if the varied coloration of the Arctic skua is really to be explained in this way, the lighter-coloured forms, especially the extreme one, in which the whole under surface is cream, ought to be on the increase, whilst the dark ones should ultimately die out or remain, perhaps, as a separate species, the intermediate tintings having disappeared. It is very difficult to form an idea of the relative number of individuals constituting any one form, because one unconsciously compares such form with a great many others instead of with each separately; but, whereas I remember various repetitions of the extreme light or half-cream variety, I have not the same clear recollection in regard to birds exhibiting other shades and proportions of cream. It was the opinion, moreover, of the man engaged to protect the sea-birds during the breeding season on Unst, that the light birds, by which he meant the ones more markedly so, were increasing in numbers. It would appear, therefore, that the process one might expect, were sexual selection the agency here at work, is in operation, and, for the rest, it is no use being in a hurry. A little patience, the "rolling" of "a few more years"—say a million—will settle the matter either one way or the other.
DUCKINGS AND BOBBINGS
T
THE eider-duck is here, but not its beauty, for at this fag-end of the summer and breeding season the males have all departed, and it is the sober-coloured female, either alone or accompanied by her little brood of ducklings, that one meets now along the shores of the island. True there must be males in their just proportion among the latter, but at this tender age—the age of fluff and innocence—the sex of a bird is in abeyance—a world that is not yet begun. A pretty thing it is to see such little family parties coasting quietly along the shore and following all its bends and indentations. There is one such now—mother and three—coming "slowly up this way," like the spring, though not so slowly as the spring, or anything at all spring or summer-like, comes to these islands. They are feeding, apparently, upon the brown seaweed that clothes, as with a mantle, each rock and smooth stone that lies upon the shallow bottom along a gently shelving beach—making a continuous fringe which is but just submerged at low tide. In this the heads of the young ones are continually buried, but the mother eats more sparingly, and seems all-in-all happy to be thus with her family. Now as the eider-duck is certainly very much of an animal feeder—supposed, indeed, to be wholly so—one would naturally think that here the food sought for is not the seaweed itself, but any live things that may be clinging to it. This, accordingly, was my provisional hypothesis, but practical investigation hardly supported it, for on examining some of the seaweed, first in one spot and then another, along the track in which the birds had swum, I could find nothing whatever upon it—noticeably bare, indeed, it was. The eyes of an eider-duck are, no doubt, sharper than my own—or anybody's. Still I do not believe that even the most sharp-sighted one could find anything on this seaweed, at least without searching for it, whereas these ducklings are constantly dipping and, apparently, as constantly feeding all the way along. Finding always, they never have the appearance of looking for what they find. To me they seem to be browsing in their little ducking way, just as sheep browse in a field.
The seaweed here is not the long, brown sort, but another and almost equally common kind, which is shorter and covered with little lobes, shaped something like an orange-pip, but of a slightly larger size—small grapes, perhaps, since they grow in bunches, is more what they resemble. They are full of a clear, gelatinous substance that might well be appreciated, and having, to the boot of all the other indications, actually seen something that looked very like one of them in the beak of a duckling, I imagine—and it is a pleasing imagination—that the latter, at any rate, derive some part of their sustenance from these their subaqueous vineries. But I have seen seaweed in the mother's bill also, and this was not only the brown sort, but a soft green variety which grows sparingly with it. When feeding, without any doubt, upon living prey, eider-ducks are accustomed to dive, going right to the bottom, and often coming up with what they find there—a crab or other kind of shell-fish—to dispose of it on the surface at their leisure. The chick can dive as easily as the grown bird, but one may watch these family excursions for a long time without once seeing either of them do so. Instead, they now merely duck to get the seaweed, which almost reaches the surface. The chicks, however, are often raised by the swell of the sea beyond the height at which they can nibble it comfortably, and it is then funny to see the hinder portion of their little bodies sticking up in the air, with their legs violently kicking, as they hold on with might and main to prevent being floated off on the wave. Sometimes a brisk one bids fair to tilt them right over, but they always ride it in the most buoyant manner. The motion with which they do so—or rather with which it is done for them—is sometimes very curious, for they look as though they were swung out at the end of a piece of elastic, and then drawn smoothly back again, just as they are on the point of turning a somersault; but more often it is a plain bob-bobbing. Thus over wave and ripple they bob lightly along, whilst their mother, floating deeper and heavier, bobs with more equipoise—a staider bob, that has much of deportment about it. Each kind has its charm—never was there a prettier family bobbing. All bob to each other—that, at least, is what it looks like—and their song, if they had one, would be certainly this:
If it wasna weel bobbit, weel bobbit, weel bobbit,
If it wasna weel bobbit, we'll bob it again.
But, for my part, I have never seen them bob it otherwise than well. They all of them bob to perfection.