In the famous "bird-city" at the north point of Sylt, the Silvery or Herring-gull plays a prominent part. Its great size, equal to that of the raven, but with much longer wings--its agreeable form, its pure white plumage, of metallic brilliancy on the back, gradually melting into light ash-blue; the velvet-black ends of the wings, with snowy feather tips, the lovely yellow eye, and the deep yellow beak, with its coral-red spot, all this together forms a beautiful picture. "There we stood," says Naumann, "surrounded by thousands, that partly hovered close over our heads, uttering their shrill screams, partly stood before us in pairs; some on their nests, the males keeping guard, some sleeping on one leg, and others leisurely stretching themselves. In one word, one hardly knew what most to admire, the uncommon cleanliness and beauty of their plumage, the great variety and elegance of their attitudes, their tameness, or the immense numbers collected in so small a space." [Illustration: Herring Gull, or Silvery Gull (Adult).] In the same "bird-city," but apart from the former, breed also the Common Gull (_Larus canus_) which is much smaller and of a more slender shape, and also the Sandwich and Caspian Terns. It is astonishing to see how each kind of sea-bird seeks its particular spot for breeding; only the auks and guillemots herd promiscuously. What may induce the birds to meet in such large bodies and then always to choose some particular cliff? The gulls yield the fortunate possessor of their district an annual income of at least two hundred rix-dollars. More than thirty thousand of the eggs, which are larger than those of the turkey, are collected every year, packed up with moss in baskets, and sent to the market. Two or three persons are busy from morning till evening, during the whole season, collecting the eggs, and receive for their trouble those of the smaller birds, which may also amount to about twenty thousand. But although the terns appear in considerable numbers on Sylt, they have chosen the small flat island, Norder Oog, to the west of Pelworm, for their chief residence. The breeding colony of the Sandwich tern amounts here to at least a million of individuals, so that when the birds are at rest, the island, at the distance of a mile, resembles a white stripe in the sea; but when their innumerable multitudes hover above it, they seem an immense white rotatory cloud. The eggs lie in some places so close together, that it is almost impossible to walk between them without treading upon them; the breeding birds often touch one another, and would not find room, if, like all sea-swallows that breed socially on the coast, they did not sit in the same posture, with their head facing the water. It is incomprehensible how each bird can find its eggs; it would even seem impossible, did we not know the miracles of animal instinct. Their noise is incessant, for even during the night they keep up a continual and lively prattle.