Gulls and Skuas are widely-ranging and essentially marine birds, even those species which nest inland being commonly observed near salt water, and seeking the coast when incubation is over. They are always inclined to be gregarious, and are more or less resident in Britain, but the undoubted influx of birds from abroad in autumn makes it difficult, or even impossible, to determine their exact status in every case. Their untiring and easy flight is only second to that of the larger Petrels; the majestic style of the Great Black-backed Gull, and other forms, being a great contrast to the wavering but graceful movements of the Kittiwake or {302}Bonaparte's Gull. All walk well, though sedately, swim to perfection, and rise easily both from land and water, usually breaking into a run before taking to the wing from the ground; while they almost invariably alight with uplifted pinions. The wild characteristic note varies less than in most large groups, that of the bigger species being harsh and querulous, that of the smaller laughing or screaming; the lesser Skuas give vent to a curious mewing cry, and the Great Skuas to a similar but deeper sound. At the breeding-quarters the utterances are naturally more agitated and shrill, and the parents hang excitedly above a visitor's head. The food consists mainly of fish, molluscs, crustaceans, and worms, but is varied in the stronger forms by small mammals, young birds, and eggs: the Great Black-backed Gull undoubtedly attacks lambs and weakly ewes; carrion is not uncommonly devoured; and _Larus maculipennis_ acts as a scavenger at Buenos Aires, besides clearing the country of grasshoppers, and robbing the Cayenne Lapwing of its insect booty. Skuas give chase to their smaller kin, and force them to disgorge the fishes they have just caught, while even Solan Geese are sometimes victimized; _Larus scopulinus_, moreover, which robs the Oyster-catcher of New Zealand, is a further instance of parasitic habits. Insects and their larvae, turnips, berries, and grain are also eaten by these omnivorous but useful creatures. Their main sustenance is naturally derived from the ocean, or its oozy shores; but flocks are commonly seen on pastures and arable lands near the beach, or following the plough further from the sea, though not being of the species which breed in the interior, nor driven inland by stress of weather. At times Gulls almost, if not quite, disappear below the water when swooping on their prey, and Kittiwakes have been said to pursue it beneath the surface. A common habit is that of preening and washing the plumage in company at favoured spots, while one that is less well-known is that of casting up the indigestible parts of the food in pellets, as do many other birds. The nesting sites are very frequently precipitous rocks and stony islands, but inland marshes and lakes accommodate many species, while in certain localities trees as high as thirty feet are selected. Skuas breed on moors