The nests are placed in a very wet and boggy place, surrounded, if possible, by water, but small ponds or tarns in marshy land are chosen in preference to large sheets of water. The nest is a large untidy heap of weeds and sticks. Four eggs, which are greenish, spotted and blotched with various shades of brown, form the usual clutch. The young hatch after about three weeks’ incubation, and are covered with pale brown down mottled with black. They leave the nest when two or three days old, but for a week or ten days at least are entirely dependent on their parents for food; after that, however, though still fed by their parents, they pick up a good deal for themselves. They fly when about six weeks old. This gull is extremely noisy at all times, but when the nesting-ground is approached the babel of harsh screams is deafening. Although usually settling on the ground, this bird can perch with ease, and does so not infrequently when at its breeding haunts. The sexes are alike, and in winter have the back pearl grey, wing feathers white with dark margins to the inner webs, head white with two indistinct dark crescents connecting the eyes and ears respectively, rest of the plumage white. Bill and legs white. In summer the head, with the exception of a narrow white circle over the eye, is dark brown. Bill and legs much darker than in summer. The young in their first plumage are mottled with pale brown, but soon become like the adult except for a black bar on the tail and pale brown wing coverts. The brown head is often only partially assumed in their first summer. Length 16 in.; wing 12 in. THE MEDITERRANEAN BLACK-HEADED GULL Larus melanocephalus, Natterer This southern species has only once been taken on our shores, though, as it visits the west of France not uncommonly, there is no great improbability in its occurrence here. Its true habitat is the Mediterranean basin. It is slightly smaller than the preceding species, and the head is jet black, _not_ brown. The beak is also stouter. In young birds the first five primaries are chiefly dark brown, whereas in our species the shafts and contiguous portion of the inner webs are white. Length 15·5 in.; wing 11·75 in. THE GREAT BLACK-HEADED GULL Larus ichthyaëtus, Pallas This species is found in Egypt, the Levant, the Red Sea, and Persian Gulf, and only one example is known to have occurred on our shores. The large size and black head are sufficient to distinguish this species when adult; young birds may be recognised by the clear-cut dark band across the tail and by the white margins to the outer webs of the secondaries. Length of male 26 in.; wing 19 in. The female is much smaller. COMMON GULL Larus canus, Linnæus This bird is by no means the commonest of our Gulls, but may nevertheless be found in fair numbers along all our coasts in winter.