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During a few weeks' ramble through the Shetland Islands, I had opportunities of studying and admiring the sea-birds, a great variety of which inhabit the rocky shores. They give animation to the coast scenery, otherwise painfully solemn, from the majesty of its stupendous cliffs, rising abruptly from the sea to form a blank wall, three and four hundred feet in height, and in a few cases towering to that of six hundred. These cliffs on the western shores of Ultima Thule are continued out to sea in a long row of pinnacles and an uninterrupted series of arches—

These fantastic forms "indicate how the attrition of the surf has told upon the iron-bound coast, demonstrating that lines of precipices hard as iron, and of giddy elevation, are in full retreat before the dogged perseverance of an assailant that, though baffled in each single attack, ever returned to the charge, and gains by an aggregation of infinitesimals the result of the whole."^[1] For these rocks are subject to the continued action of the fierce Atlantic waves, hollowing out the more easily degraded parts of these crystalline rocks, piercing them, and detached portions as needles; awaiting the final change when they shall be ground to sediment, and so assist in the building up of like structures; and thus it is we see everywhere around us that this apparent destruction is the real source of renovation in nature.

It is among these cliffs and natural caves that multitudes of sea-birds scream aloft in middle air, and have their homes; here they resort for the purpose of breeding, each species associating together in vast communities, and usually isolated from others. Here is a cave, the haunt of the Kittawake; the top of that little shelving holm is crowded with the nests of the common Gull; on yon ledge of rock, scarcely wide enough for the eggs to rest on, is a long rank of Guillemot's eggs; around that beetling cliff the Rock Pigeon is seen whirling in rapid flight; here and there on the face of the same, are the burrows of the Little Puffin. Many of these species breed together in apparent harmony and good-will.

But the most secluded of all the sea-birds are the Skua Gulls, a species of a very interesting nature from their peculiar habits and form, so ungull-like. They are characterized by their boldness, rapid flight, and by supporting themselves chiefly on the fish which they compel other gulls to vomit. Of the Skua Gulls, three species frequent the Shetlands Archipelago,—the Skua Gull, or Bonxie; the Richardson's Skua, or Arctic Gull; and the Pomarine Gull: they belong to the genus Lestris of naturalists, and though closely allied to the true Gulls (Larus), yet they appear to partake both of the nature of the Gull and Hawk tribes.

The Richardson's Skua, with the scientific appellation, Lestris Richardsoni, is a very elegant bird, of a blackish colour all over, with the exception of the belly, which is of a rusty or tarnished hue; not unfrequently this gives place to a pure white; others with the breast more or less speckled graduate from the white to the rusty. The Shetlanders regard the black and white bird as the male; but the varieties of colour are without doubt the effect of different periods of development, as one may see, where there are numerous individuals, pairs belonging to the same nest associated in every possible combination of colours; for evidently this species breeds before it attains the plumage of maturity.

The bird is seen to advantage on the wing; its truncated tail, with the middle feather prolonged beyond the rest, its long arched wings, and its rapid flight, suggest to the casual observer the flight of the Hawk. This impression would increase upon us, if we should witness its piratical propensities exercised among the Kittawakes and small gulls. Thus, while one of the parents birds remains watching over its progeny, its male sallies forth to secure wherewith to appease the hunger of its family. But the Richardson knows only one law of possession, that which the strong exercises over the weak: might is right with him. Poised on wing, or sailing to and fro over the fishing-grounds of the smaller gulls, he awaits a capture by one of them, and while the poor bird speeds on his homeward journey, the Richardson is after him, and through his superior power of flight overtakes him, worries the poor gull, and to escape this persecution the victimized bird disgorges its fairly-acquired prey; as it falls, it is seized by the tyrant, who hurries home with his ill-gotten gains. The cry of this gull is shrill and peculiar in tone, and in the solitude of a summer's midnight-twilight strikes on the ear of a person, a stranger to it, as an agonized wail of a child.

There are many breeding stations of this bird throughout the islands, though there are rarely more than a few pairs congregated in one place, yet on Comb Hill, in the island of Foula, which these gulls have appropriated to themselves for the purpose of nidification, as many as from fifty to one hundred pairs may be observed.

Unlike the majority of the Gulls, the Richardson's Skua selects for a breeding-place the heathy and treeless moors at various altitudes, and distant a