British Sea Birds - Charles Dixon

Скачать книгу

covered with marine herbage, varied with barer patches, and with beaches of rough shingle. Similar conditions are sought on the mainland, in a secluded spot on the coast, but an island is always preferred. The Sandwich Tern is gregarious, but its colonies, with one exception, in our islands are nowhere very extensive. This one exception is at the Farne Islands, where it has been computed the birds number upwards of a thousand pairs. As the nesting-places are visited very regularly year by year this Tern probably pairs for life. I have noticed, however, that the birds shift their actual breeding ground from time to time, using several spots in succession. One year they will nest here, another year there, on the same small island perhaps, but sometimes removing en masse to another one of the group. The nests are always placed upon the ground, either amongst the sand shingle and drifted debris, a short distance from high water mark, or amongst the sea campion, thrift, and coarse grass further inland; sometimes a bare mound on the highest part of the island is selected. Many nests are made within a small area, sometimes so close together as to render walking amongst them without treading on their contents a difficult matter. The nests are slight enough, mere hollows lined with a few bits of withered herbage, and in some cases even this simple provision is neglected. The eggs, which are laid from about the middle of May to the middle of June, are generally two in number, but sometimes three. These vary from creamy-white to rich buff in ground colour, handsomely blotched and spotted with various shades of brown and gray. During the hot June days the eggs seem to require little incubation, but there are always plenty of birds about the spot, ready to rise fluttering and screaming into the air when their breeding grounds are invaded by man. But one brood is reared in the season, yet if the first clutches of eggs be lost they will be replaced.

COMMON TERN

      This Tern, known as the Sterna hirundo of Linnæus, by most British ornithologists, although there can be little doubt that the great Swedish naturalist applied the term indiscriminately to this and the Arctic Tern, is one of the best known British species, especially round the English and Welsh coasts. It becomes rarer in Scotland, where it is largely replaced by the Arctic Tern. The Common Tern, distinguished by its white underparts from the Arctic Tern, is migratory and arrives on the British coasts towards the end of April, retiring south in Autumn. Its favourite haunts during the summer are the various groups of low rocky islands, and the more secluded portions of the coast where sandbanks and shingle occur. Save on passage, this Tern is seldom seen far from the vicinity of its nest colony. The flight of the Common Tern is exceedingly buoyant and graceful, the long slender wings and acutely forked tail assisting greatly in the general effect. Like the Swallows the tarsus of the Terns is remarkably short, so that on the ground the birds seem awkward, and rarely attempt to walk far; on the sea, however, they are quite at home and swim well. There are few prettier sights along the shore than a flock of Terns busy in quest of food. Where the beach is rocky, and the water somewhat deep inshore, the birds may be watched with ease. In a serried throng they flutter to and fro; ever and anon a bird falls down like a fragment of white glittering marble into the sea with a loud splash, and in a moment rises again with its finny prey. Bird after bird keeps dropping so; now and then a bird remains swimming on the water; now and then two birds chase each other in rapid flight. And so for miles the Terns will continue to follow the shoal until hunger is satisfied, or the fish retire to greater depths. The food of this species is chiefly composed of small fish, but insects and crustaceans are also devoured. The note of the Common Tern is a shrill krick or kree-ick, most frequently uttered when the bird is flying alarmed over its invaded nesting place.

      The Common Tern is rather a late breeder, its eggs not being laid until the end of May or early in June. It breeds in companies of varying size, the suitability of the site being in some measure a determining cause. This Tern is equally capricious in the site selected for the nests; sometimes one spot is chosen, sometimes another; but there can be little doubt that the bird pairs for life, and evinces considerable attachment for its accustomed haunts. I have found almost invariably that the Common Tern habitually lays its eggs farther from the water than the Arctic Tern, and always prefers to conceal them amongst vegetation of some kind. Islands are always preferred to the mainland, doubtless because of their greater safety. We cannot class this bird as an elaborate nest builder, a mere hollow, scantily lined with a little withered grass or weeds, being the only provision. The two or three eggs vary from buff to grayish-brown in ground colour, blotched and spotted with several shades of rich brown and gray. But one brood is reared, and as soon as the young are strong upon the wing, the nesting places are deserted, and the movement south begins.

      Terns migrate leisurely in autumn, often remaining a day or so here and there, on and off the coast, and are then seen in localities which they never frequent during summer.

THE ARCTIC TERN

      This Tern, widely known to systematists as the Sterna arctica of Temminck, was unaccountably confused with the preceding species, until the German naturalist, Naumann, appears first to have pointed out their specific distinctness. The Arctic Tern is par excellence the Tern of our northern coasts, say from the Farne Islands and Lancashire onwards to the Orkneys and the Shetlands. I am not aware that it breeds anywhere on the English coast between Spurn and the Scilly Islands, but there are a few scattered colonies on the west coast of England and Wales. This pretty Tern may be distinguished from its near ally, the Common Tern (which it closely resembles in size and general appearance), by its grayer under parts and perceptibly longer outermost tail feathers. Like all its congeners, the Arctic Tern is a summer migrant to the British seas and coasts, arriving from the south late in April or early in May. It prefers very similar haunts to those of the preceding species – low rocky islands with sandy or shingly beaches, and with a fair amount of grass and other marine vegetation upon them. It is equally gregarious in its habits, breeding in colonies, and returning regularly to certain districts to rear its young. Its slenderer form, and proportionately longer wings and tail, make it even more elegant looking in the air than its congener. It catches its food in the same Hawk-like or Gannet-like manner, pouncing down into the water and seizing the tiny fish as they swim near the surface. No Tern dives, and it is certainly exceptional for the bird completely to immerse itself; usually it flutters on the surface for a moment, then rises again. Small fish and crustaceans form the principal food of this species. Its note is very similar to that of the preceding Tern – a shrill and monotonous krick, often prolonged into two syllables.

      The nesting season of this Tern begins in June, and fresh eggs may be found throughout that month. Rocky islands seem everywhere to be preferred for nesting places, and the same habit of changing the exact hatching ground prevails in this as in the preceding species. The Farne Islands are, or used to be, a great breeding station of the Arctic Tern, and there I have taken great numbers of its eggs. The bird probably pairs for life. It differs somewhat in its nesting arrangements from the Common Tern, inasmuch that it never makes any nest. No lining of any kind is placed in the hollow which contains the eggs, and this hollow is generally selected ready made. Another peculiarity is that the eggs are far more generally laid nearer to the water; and this applies not only to the Farne Islands, but to every breeding place of this Tern that I have visited. The two or three eggs are laid in any little depression in the coarse sand or shingle on the line of drift, or amongst small pebbles, or even on the bare ground or rock. These eggs vary from buff to olive, and even pale bluish-green in ground colour, heavily blotched and spotted, especially at the larger end, with dark brown, paler brown, and gray. They are decidedly smaller than those of the Common Tern, more elongated in shape, and are much more olive in general colour. When disturbed from their eggs the Arctic Terns become very noisy, and rise in fluttering crowds above the sacred spot, continuing to fly to and fro, screaming anxiously until the intruder retires.

ROSEATE TERN

      It is with some hesitation that I include this species, the Sterna dougalli of Montagu, in the present work, because if it really does visit our coasts now to breed, it is so exceedingly rare and local, that any ordinary observer of bird life by the sea could scarcely hope to meet with it. It is interesting to remark that the Roseate Tern was first made known to science from a skin that was sent to Montagu, from the Cumbrae Islands, in the Firth of Clyde. It was subsequently found breeding on the Farne Islands by Selby; it formerly bred on the Scilly Islands, as well as on Foulney and Walney; but so far as I can ascertain there is no direct evidence that it breeds at any of these places now. It may be distinguished from the Common Tern by its rosy under plumage; but as this is

Скачать книгу