[Illustration: The Lesser Black-backed Gull.]
Next to the Lesser Black-backed Gull the Terns are certainly the most numerous and most interesting birds. Three out of the five British species return each spring to these famous islands to breed. The Roseate Tern, rarest of all the indigenous species, used formerly to breed here, but it eventually became extinct, although from time to time an odd pair or so are observed in their old-time haunts, so that the bird may re-establish itself in them, more especially as the sea-birds are now so strictly preserved there. The three regular breeding species are the Sandwich Tern, the Common Tern, and the Arctic Tern. All are summer migrants only to the British Islands. The Sandwich Tern, by far the largest of the three species, arrives at the islands during the last half of April, as a rule, but some seasons is not seen until the beginning of May. There is much in their early movements that reminds us of the actions of Rooks just previous to nesting. Every morning for perhaps a month after their arrival they assemble at the islands and stay for a short time, previous to dispersing over the surrounding sea to search for food, lingering longer and longer as the actual breeding time approaches, until they finally decide upon a spot to nest, and about a week after this the first eggs are laid. The laying season lasts a month, say from the middle of May until the middle of June. The earliest young may be remarked about the latter date, and from that time onwards rapidly increase in numbers from day to day. July is a busy month indeed for the parent birds. In exceptionally early seasons some of the young are able to fly by the beginning of August, and by the end of the month the birds quit the breeding-place, and finally desert the vicinity of the islands during the first week in September. Sometimes the autumn exodus is made, but the birds return in a day or so and linger about the islands before finally taking their departure south. The Sandwich Terns do not always breed in exactly the same spot every season. Sometimes an exceptionally high spring-tide will wash away most of the eggs, and then the poor birds move to another situation, perhaps to another island, and try again. This happened in the summer of 1883, and we saw the beach literally strewn with broken egg-shells, the sole remains of the wrecked colony. On our way from the beach towards the barer rising ground in the centre, where the main colony chances to be established, we pass many outlying nests, not only of this Tern, but of Gulls and Eiders. Birds are rising from all parts of the ground, and gradually congregating into a dense bewildering, drifting, noisy throng above our heads. At last we reach the colony of Sandwich Terns, and there we find for an area of many square yards the ground literally covered so closely with eggs that to walk amongst them without breaking them is almost an impossible feat, not only because the nests are but a few feet apart, but because the eggs themselves so closely resemble the ground in colour. The nests are slight enough, many of them nothing but hollows in the ground, some of them with a few bits of weed and grass loosely arranged, and chiefly round the margin. The two, or less frequently three, eggs are very beautiful objects, and vary enormously in the character of the markings. The ground colour may be any shade between rich buff and dull white; the markings are brown of many shades, and ink-gray. These latter vary considerably in shape and size, from large irregular blotches that conceal nearly a third of the shell to splashes, spots, and streaks, sometimes distributed over the entire surface, or in zones, or irregularly here and there. During the whole period of our stay the birds remain above us, fluttering and gliding to and fro uttering shrill notes of alarm.