or hills near the sea in Scotland, on the fells of Scandinavia, and on the tundras and barren grounds of the Arctic Regions, the nest being a mere depression in the herbage or moss; the {303}remainder of the tribe generally collect a mass of grass, moss, flags, sedges, heather, twigs, or sea-weed, though a mere hollow in the soil or sand often serves their purpose. The eggs vary in number from two in the case of the Ivory Gull and the Skuas to three or exceptionally four; they are brown, drab, or green, with blotches and spots of brown, black, grey, and lilac, and recall those of Plovers. Both sexes have been said to incubate in _Larus minutus_ and _Rissa brevirostris_; the young are comparatively helpless for a few hours or perhaps days, and are at first fed by the parents. Terns resemble Gulls in many of their habits, but are more cosmopolitan, and decidedly migratory in Britain; they are essentially marine, yet some species breed on inland waters in summer. Particularly slender and graceful, these long-winged birds may usually be distinguished by their irregular or hovering flight, and are known as Sea-swallows; while their method of beating up and down maritime streams or shallows, singly or in pairs, in search of fish, is quite peculiar to themselves. At such times they make constant plunges into the water, often completely immersing their bodies, or occasionally discontinue their operations to engage in trivial and seemingly amicable quarrels. The note, though hoarse in some cases, is usually a squealing or grating sound, the latter especially when disturbed; the food consists of fish and crustaceans, insects–said to be sometimes taken on the wing–frogs, newts, locusts, grasshoppers, caterpillars, leeches, molluscs, and medusae. Terns are wary but bold, commonly circling around a wounded companion until several are shot; the Noddies (_Anous_), however, are much more sluggish and silent. On the ground all move with comparative ease. The nest of _Hydrochelidon_ is a mass of water-weeds placed on some tussock in a wet inland swamp; that of _Anous_, when situated on trees, bushes, or rocky ledges, is composed of twigs, sea-weed, and like materials; but most species merely make a hole in the sand or soil, with little or no lining. Depressions on level rocks, the surface of prostrate plants, and heathery, grassy, or muddy flats are often utilized as alternatives, while colonies are usually formed. Two or three olive, reddish-brown, green, or stone-coloured eggs, with blotches, spots, scrawls, or oblique streaks of black, brown, grey, or lilac, are deposited; the Noddy and Sooty Terns, however, have a single white egg with red markings, and _Gygis_ one, which is buff, marbled, spotted, or often scrolled with brown and grey, and is laid on any slight cavity of {304}a branch, a broad leaf-stalk, or a coral reef. The nesting habits of _Naenia_ are unknown, but it frequents rocky, cavernous shores.