Several species of gulls are of common occurrence on St. Kilda: _Larus marinus_, _fuscus_, _canus_, and _tridactylus_. The last, or kittiwake, is the most abundant; a social bird, choosing the most inaccessible spots. On disturbing a colony of kittiwakes, most of the birds leave their nests and fly about the intruder, uttering incessantly their clamorous but not unmusical cry. The noise from a large flock is almost deafening; the flapping of their wings and their loud screams, joined to the deep guttural notes of the passing gannets, and the shrill tones of the larger gulls, form a combination of sounds without a parallel in nature. Probably on account of its vigilance, the kittiwake is not pursued by the fowler. The fulmar breeds in almost incredible numbers on St. Kilda (the only place in Britain where he is found), and is to the natives by far the most important production of their barren land. On the crest of the highest precipices, and only on such as are furnished with small grassy shelves, on every spot above a few inches in extent, the fulmars have taken possession of the rock. On being seized, they instantly disgorge a quantity of clear amber-coloured oil, which imparts to the whole bird, its nest and young, and even the very rock which it frequents, a peculiar and very disagreeable odour. Fulmar oil is one of the most valuable productions of St. Kilda. The best is obtained from the old bird by surprising it at night upon the rock, and tightly closing the bill until the fowler has seized the bird between his knees with its head downwards. By opening the bill, the fulmar is allowed to eject about a table-spoonful, or rather more, of oil into the dried gullet or stomach of a solan-goose. The islanders use fulmar oil for their lamps, and consider it as an infallible remedy against chronic rheumatism.