Both the sexes share in the duty and pleasure of incubation, and (as in some other species) to see them relieve each other on the nest is to see one of the prettiest things in bird life. The bird that you have been watching has sat patiently the whole morning, and once or twice as it rose in the nest and shifted itself round into another position on the eggs, you have seen the gleam of them as they lay there
"As white
as ocean foam in the moon."
At last when it is well on in the afternoon, the partner bird flies up and stands for some minutes preening itself, whilst the one on the nest, who is turned away, throws back the head towards it and opens and shuts the bill somewhat widely, as in greeting, several times. The newcomer then jumps and waddles to the further side of the nest, so as to front the sitting bird, and sinking down against it with a manner and action full both of affection and a sense of duty, this one is half pushed, half persuaded to leave, finally doing so with the accustomed grotesque hop. As it comes down on the rock it turns towards the other who is now settling on to the eggs, and, throwing up its head into the air, opens the bill so as to show (or at any rate showing) the brightly coloured space within.
All this it does with the greatest—what shall we say? Not exactly empressement, but character—it is a character part. There is an indescribable expression in the bird—all over it—as of something vastly important having been accomplished, of relief, of satisfaction, of summum bonum, and, also, of a certain grotesque and gargoyle-like archness—but as though all these were only half-consciously felt. She then (for I think it is the female), before flying away, picks up a white feather from the ledge and passes it to the male, now established on the nest, who receives and places it. It has all been nearly in silence, only a few low, guttural notes having passed between the birds, whilst they were close together.
Just in the same way the birds relieve each other after the eggs have been hatched and when the young are being fed and attended to.
"A shag (I think the female bird) is sitting on her nest with the young ones, whilst the male stands on a higher ledge of the rock a yard or so away. He now jumps down and stands for a moment with head somewhat erected and beak slightly open. Then he makes the great pompous hop which I have described before, coming down right in front of the female, who raises her head towards him and opens and closes the mandibles several times in the approved manner. The two birds then nibble, as it were, the feathers of each other's necks with the ends of their bills, and the male takes up a little of the grass of the nest, seeming to toy with it. He then very softly and persuadingly pushes himself against the sitting bird, seeming to say, 'It's my turn now,' and thus gets her to rise, when both stand together on the nest, over the young ones. The male then again takes up a little of the grass of the nest, which he passes towards the female, who also takes it, and they toy with it a little together before allowing it to drop. The insinuating process now continues, the male in the softest and gentlest manner pushing the female away and then sinking down into her place, where he now sits, whilst she stands beside him on the ledge. As soon as the relieving bird has settled itself amidst the young, and whilst the other one is still there—not yet having flown off to sea—it begins to feed them. Their heads—very small, and with beaks not seeming to be much longer in proportion to their size than those of young ducks—are seen moving feebly about, pointing upwards, but with very little precision. Very gently, and seeming to seize the right opportunity, the parent bird takes first one head and then another in the basal part, or gape, of his mandibles, turning his own head on one side in order to do so, so that the rest of the long bill projects sideways beyond the chick's head without touching it. In this connection, and whilst the chick's head is quite visible, little, if any more than the beak being within the gape of the parent bird, the latter bends the head down and makes that particular action as of straining so as to bring something up, which one is familiar with in pigeons. This process is gone through several times before the bird standing on the ledge flies away, to return again in a quarter of an hour with a piece of seaweed, which is laid on the nest." Here again, as throughout, the sexes of the birds can only be inferred or merely guessed at. Both share in incubation, both feed the young, both (I think) bring seaweed to the nest, and both are exactly alike.
As the chicks become older they thrust the head and bill farther and farther down the throat of the parent bird, and at last to an astonishing extent. Always, however, it appeared to me that the parent bird brought up the food into the chick's bills in some state of preparation, and was not a mere passive bag from which the latter pulled out fish in a whole state. There were several nests all in unobstructed view, and so excellent were my glasses that, practically, I saw the whole process as though it had been taking place on a table in front of me. The chicks, on withdrawing their heads from the parental throat, would often slightly open and close the mandibles as though still tasting something, in a manner which one may describe as smacking the bill; but on no occasion did I observe anything projecting from the bill when this was withdrawn, as one would expect sometimes to be the case if unmodified fish were pulled up, but not if these were in a soft, porridgey condition. Always, too, the actions of the parent bird suggested that particular process which is known as regurgitation, and which may be observed with pigeons, and also—as I have seen and recorded—with the nightjar.