the fish, being alive, as it probably would be, had, by a remarkable conjunction of two lucky accidents, escaped. But, on the other hand, would the herring-gull have dared to interfere with the skua?—which it would have been doing, were the latter in the habit of picking up the fish from the water. On other occasions I have seen the skua fly off as soon as he had missed his swoop, and I have once seen a herring-gull following the chase, with a view, as seemed obvious, to such a contingency. This happened on the island, so that I remember it quite plainly, though, what with one thing and another, it got crowded out of my notes. I was, however, much interested at the time, for it pointed to a possibility of a further and more complex development of these curious parasitic relations; for why should not gulls become, in time, the constant attendants of such chases as these, on the off-chance merely of the skua failing to get the fish that he had forced the bird he was chasing to drop? Here would be a secondary act of piracy grown out of the first and more direct one.
Herring-gulls—they are much the commonest species here—seem now to feed a good deal on the floating carcases of young kittiwakes, so I think it likely that the bird I twice saw doing this before, and took each time for a grown kittiwake, was really a herring-gull. It was at some distance, and I jumped to a conclusion without taking the trouble to verify it. But are these young kittiwakes first killed by the gulls, or found dead by them merely? As to this I
