The Bird Watcher in the Shetlands/Chapter 26
I HAVE just seen a sea-pie several times pull and tweak with his bill at the seaweed, apparently, till he secured something that had a white appearance. Holding this between the extreme tip of his mandibles, he each time retired up the rock with it, placed it, as it seemed to me, amidst some seaweed, and then ate it. This was looking down upon a great stack of rock at some distance, so that it was impossible to be certain in regard to such minutiæ. It seemed to me, as it has seemed before, that he had pulled, not hit, some small limpet or other shell-fish from off the seaweed, and then wedged it amidst other seaweed higher up so as to be able to pick out the inside more easily. Possibly, however, he merely laid it down without wedging it, but I cannot tell, and it is very difficult to get close enough to see just what these birds really do when they feed. On the grass, which they probe like starlings, one can get a pretty good sight of their actions, but not on the seashore. One thing I cannot help noticing, that whereas limpets are all about on the rocks and need no looking for, they walk about as if they were looking for something, and they leave the bare rock that is all stuck over with them for the parts that are covered with seaweed, and at this they pull and tweak. In spite, therefore, of the peculiar wedge-like bill with its obtuse tip that seems so well adapted for striking a limpet or other shell-fish with a sudden blow from the rock to which it had been clinging, I am beginning to doubt whether they often use it in this way, and especially whether limpets are a special food of theirs. I remember, however, once seeing a sea-pie make just the sort of blow required on the theory, but ineffectively, and in a peculiar half-hearted way, as a man might feebly clench his fist and strike in his sleep. It is curious that this trivial action, which seemed to be of an involuntary nature, made under a misapprehension discovered in time to check, but not to stop, the blow, has remained in my memory with a strange persistence and vividness, and on the strength of it I still think that limpets are sometimes struck from the rock in this way. There must, I think, have been something very specialised in the movement of the head and bill, slight as it was, to make me retain it so long in my mind's eye.
Afterwards I watched several of these birds feeding on the rocks, and I distinctly saw one with his beak amongst a bed of the same small blue mussels that I have seen the eider-ducks feeding on, picking and pulling at them in much the same way. Others, like the first one, pulled at the brown, or black, seaweed with which the rocks are plentifully hung. They ran down upon it when the sea receded, and back, or else jumped into the air or flew to another rock, when it foamed in again. The sea boils in about the rocks off these iron shores in a tremendous manner, even when, like to-day, it is quite calm. On the stillest day, indeed, there is often a sullen swell which makes varying patches and long chequered lines of foam all around them. The sea never sleeps in these islands—only slumbers uneasily like some terrific monster that anything may awake.
It is observable that some of these sea-pies are bolder than others in outstanding the swell of the waves. Some flee it before it comes, others fear not to have it wet their feet, whilst others, again, will almost risk being soused in it. But are these different birds, or are they all different at different times? On that, of course, must depend whether a process of differentiation, on evolutionary lines, is in action amongst them or not. For myself, I think the first, and that, from waders or paddlers, some of these birds may in time become swimmers—which would make them a sort of sea moorhen. The redshanks has gone farther in this direction, for he sometimes swims, but I know of no intermediate form, no sea and sea-shore bird corresponding to our moorhen or coot.—Mussels, then, and the beak thrust in amongst seaweed; but no limpets up to the present. Now limpets, as I said before, are all over the rocks, and so need no searching for. Why so chary, then, if the birds really affect them?
What ails ye at the puddin'-broo
That boils into the pan, O?
Under favourable circumstances—solitude and non-molestation are, no doubt, the most favourable—oyster-catchers leave the foreshore, and browse, in flocks, over the grass-land beyond it. There are now, for instance, twenty-one, at the least, browsing, and I have watched them for some time digging their beaks well into the soil—to half their length, perhaps, sometimes—and then tugging violently at something. What this was, however, I could not, in any case, make out. It appeared to be taken into the beak before the latter was withdrawn. At last, however—for I like to see it all through the glasses, if I can—I went to the place, and, going down on my hands and knees, commenced a minute investigation. All about were round, straight holes going down through the grass into the turf, like those on a lawn after starlings have searched it, but, of course, larger. With my knife I cut down into several of these, and in two or three I found a small worm quite near the surface of the soil. It seemed as though the bird's bill had passed it in looking for or aiming at another one deeper down. Be this as it may, worms, it seems likely, form a common food of the sea-pie, for what else could these ones have been searching for? Worms, however, must be taken to include grubs, caterpillars, and so forth, an ordinary land diet, in fact, and did these birds get to preferring it, their habits would rapidly change. These, I should think, must a good deal depend upon locality, and perhaps, too, on their numbers, for birds become bolder when they go many together. Even here the sea-pie is wary, and in a more populous place I doubt if anything would tempt him inland. Yet it is curious that in an island where I have been the one inhabitant I have never seen these birds feeding or walking anywhere except on the tidal shore, quite near the sea, though they often flew over the island, whereas here, in Unst, I have seen them thus searching the green-sward in the neighbourhood of Burra Firth, which is a village, though a small one. But then they are much more numerous here, and it was always in the close neighbourhood of the beach, even when not upon it, that I saw them. In this last instance, too, they were no distance at all from the sea—but again, most of the smooth, turfy stretches, where it would be easy to find worms, are so situated. Here, then, is another path along which differentiation might proceed, and by which, in time, an oyster-catcher might become a bird with the habits of the great plover. It is curious that one of the cries of the latter bird in the spring, though very much weaker, is a good deal like the "ki-vick, ki-vick, ki-vick, ki-vick, ki-vick!" of the sea-pie, so that the one rendering might stand for both.
It is pleasant to see a fair-sized flock of these birds gathered together on a smooth stretch of sand just above the line of the waves. Some walk about or stop to preen themselves, others lie all along, whilst a few stand motionless upon one leg, fast asleep, with the head turned and the red bill hidden amongst the pied plumage. Sometimes, when excited, or about to fly, they will run, for a little, over the sand, holding the wings elevated above the back, which has a quaint yet graceful appearance. They keep together, generally, in a group or series of groups, but at other times stand in a long row amidst or but just beyond "the light sea-foam" beating from the waves, looking as though the sea had cast them up, like a line of drifted seaweed. Gulls often come down amongst them, and the two sit or stand, side by side, quite indifferent to one another, each hardly conscious of the other's presence—so far, at least, as one can judge. Besides the piping note I have mentioned, these sea-pies have others—"queep, queep!" and a kind of twittering trill leading up to it—which remind one strangely of the great plover, and suggest a common ancestry.
I have confirmed to-day all that I said in Bird Watching (pp. 90-3) about the love-piping of these sea-pies. For some reason or other—rivalry, I think, passing into a form—two birds, that I put down as males, seem to like to pipe together to one who, by her quiescence and general deportment, I judge to be the female. I have seen this twice since coming here, once yesterday, and now again within these few hours. This last time it was almost as marked as in the instances I have described, and towards the end one of the piping birds showed a tendency to go down on his shanks, as though kneeling to his lady love. I do not think he quite did this, but he bent towards it. I am convinced myself that the dance of three peewits, as described by Mr. Hudson in The Naturalist in La Plata, has had some such origin as this. What one wants, in order to arrive at the real nature of the latter, is a number of detailed descriptions, instead of a mere general one, never in my opinion of much value in such matters. Pains, also, should be taken to ascertain the sexes of each of the three birds that takes a part in the show.
Another nuptial sport or play which these birds indulge in belongs to air—where, indeed, they pipe as strongly and easily as upon the ground. This that I speak of, however, appeals in an equal degree to the eye and ear. Two birds pursue each other closely, mounting all the while in a steep slant, till, having gained some elevation, both turn at an acute angle, and descend in the same manner, in a reversed direction, thus tracing the shape of a pyramid. Having completed the air-drawn figure, they immediately reproduce it, and thus they continue on quickly vibrating wings—now upwards, far above the cliff-line, now downwards, almost to the sea—piping the whole time in the fullest-throated way. Even in a small and sober-suited bird such a performance might attract attention. How much more here where, to the boot of the large size of the two artistes, and the noise they make, the boldly contrasted black and white of their plumage, the deep rose-red of the bill, and pale rose-pink of the legs, give it a very lovely appearance. For myself, I have seen few things more striking.