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Common Tern


Common Tern


The definitive website on wildbirds & nature



Birds of America

By John James Audubon, F. R. SS. L. & E.

VOLUME VII.

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COMMON TERN.
[Common Tern.]

STERNA HIRUNDO, Linn.
[Sterna hirundo.]

PLATE CCCCXXXIII.--ADULT MALE.

Although the Prince of MUSIGNANO has thought that the bird named the Common Tern in America, differs from that bearing the same name in Europe, and has in consequence changed its appellation to that of Wilson's Tern, I am of opinion that no difference exists between the Common Terns of the two Continents. The cry of both is besides precisely similar, so that with me there is no doubt whatever as to their identity. Experience has shewn me that the markings or white spots on the primary quills of Gulls, at one time assumed as a criterion by which species might be distinguished, cannot in the least be depended on, varying, as they always do, in individuals of the same species, at almost each successive moult. Then why, reader, should not Terns exhibit analogous changes? The fact is, they do so; and it is almost impossible, on closely inspecting a dozen or more specimens procured at the same period, in either country, to find two individuals exactly corresponding in every particular. Some have the bill almost entirely black, while others have it more or less red and black, and tipped with yellow. The length of the tail-feathers, that of the tarsus, and the size of the inter-digital membranes, are all found to differ in some degree, if minutely compared.

If species are to be founded on such slight differences, an ample field is open to those who are ambitious of being discoverers. At all events, I cannot help remarking here, that it seems to me improper to impose new names on objects, until it is proved by undeniable facts that they present permanent differences.

I have observed this species along the Atlantic coast of North America, from Galveston Island in Texas to the Straits of Belle Isle on the coast of Labrador, both in spring and in early autumn. But when on the islands in Galveston Bay, in the month of April, I saw only a few arriving there from the west; whereas, in the beginning of May great numbers arrived there from the east, settled at once, and commenced breeding. I felt convinced that the numbers which came from the direction of the Floridas were much greater than those which arrived from the westward, and judged it probable that vast numbers had at the same time left the Peninsula on their way northward. Should other travellers observe the same or similar phenomena at the season mentioned, it will be proved that this species does not extend its autumnal migration so far as several others, which I observed arriving at Galveston Island from the south-west, for example, the Least Tern, Sterna minuta, the Cayenne Tern, St. cayana, and the Black Tern, St. nigra.

The Common Tern commences breeding on the coast of our Middle Districts about the 5th of May. On my voyage to Labrador, I found its eggs on the islands in the Gulf of St. Lawrence, and especially on the Magdalene Islands, which I visited on the 11th of that month. On the 18th I saw them in great abundance in the neighbourhood of American Harbour, on the coast of Labrador, where thousands of Terns were plunging headlong after shrimps all round us. In that country, their eggs were deposited among the short grass, and the places which they occupied were but slightly scratched; whereas, on the Magdalene Islands, were they breed on sandy ridges, slight hollows were scooped out, as is generally the case along the eastern coast of the United States. Their sojourn in Labrador is of short duration; and when we were at Newfoundland, on the 14th of August, multitudes were already passing southward. At the same period considerable numbers pass by an inland route from the Canadas, and all our great lakes, travelling along the Ohio and Mississippi. While residing at Henderson, and afterwards at Cincinnati, I had ample opportunities of watching their movements in the month of September. And yet, you will think it strange, that, during their vernal migration, I never saw one ascend any of these rivers or the streams connected with them. Perhaps the inferior temperature of the waters, compared with those of the ocean, in the early spring months, may induce them to abandon their route at that season. In autumn, on the contrary, when these rivers are heated and reduced in size, the Terns may find in them an abundant supply of the fry of various fishes. It would thus appear, being corroborated by other observations which I have made relative to migration, that species whose range is extensive, are determined in their movements by a genial temperature and an abundant supply of food.

With an easy and buoyant flight, the Tern visits the whole of our indented coasts, with the intention of procuring food, or of rearing its young, amidst all the comforts and enjoyments which kind Nature has provided for it. Full of agreeable sensations, the mated pair glide along side by side, as gaily as ever glided bridegroom and bride. The air is warm, the sky of the purest azure, and in every nook the glittering fry tempts them to satiate their appetite. Here, dancing in the sunshine, with noisy mirth, the vast congregation spreads over the sandy shores, where, from immemorial time, the species has taken up its temporary abode. They all alight, and with minced steps, and tails carefully raised so as not to be injured by the sand, the different pairs move about, renew their caresses, and scoop out a little cavity in the soil. If you come again in a few days, you will find the place covered with eggs. There they lie, three in each hollow, beautifully spotted and pointed; and as they receive heat enough from the sun, the birds have left them until evening. But not absent are they from the cherished spot, for they have seen you, and now they all fly up screaming. Although unable to drive you away, they seem most anxiously to urge your departure by every entreaty they can devise; just as you would do, were your family endangered by some creature as much stronger than yourself as you are superior to them. Humanity fills your heart, you feel for them as a parent feels, and you willingly abandon the place. The eggs are soon hatched; the young in due time follow their parents, who, not considering their pleasant labour ended when they are able to fly, feed them on wing in the manner of Swallows, until they are quite capable of procuring their subsistence themselves. So soon as this is the case, the young birds fly off in bands, to seek on distant shores, and in sunny climes, the plentiful food which the ocean yields.

The nest of the Common Tern is, as I have said, a mere hollow made in the loose sand of some island or mainland beach, scantily tufted with wiry grass, or strewed with sea-weeds. Their eggs never exceed three in number; their average length is 1 inch 5 1/2 eighths, their breadth 1 1/4 inches. They vary greatly in their markings, as is the case with those of all the smaller species of this family; but their ground colour is generally pale yellowish-green, blotched and spotted with brownish-black and purplish-grey or neutral tint.

The young, which are fed with small fishes, shrimps, and insects, separate from the old birds when fully fledged, and do not again associate with them until the following spring, when both are found breeding in the same places. It seems quite curious to see these young birds in winter, during boisterous weather, throwing themselves into the remotest parts of estuaries, and even visiting salt-water ponds at some distance from the sea, as I have often seen them do at Charleston, in South Carolina, when accompanied by my friend the Rev. Dr. BACHMAN. Their plumage is then so very different from that of the old birds, that one might readily believe them to be of another species, did he not observe that their mode of flying and their notes are the same. Not less strange is it, that on such occasions none of the old birds are to be seen in the place, they having remained, braving the fury of the tempest, on the outer harbours. In the beginning of winter, young birds also sometimes ascend the Mississippi as far as Natchez; and in the same manner betake themselves to all the large lakes bordering the Gulf of Mexico. There, as well as elsewhere, you see them plunge into the water, and instantaneously secure their prey, rise as quickly, and dash into another spot hard by, whenever food happens to be abundant.

I have many times seen the Common Tern suddenly fly up and come close over a man or a dog, without the least apparent provocation, indeed when far distant from its nest, and then pass and repass repeatedly within a few yards, emitting a plaintive cry, as if its eggs or young were in the immediate vicinity. At other times, when the birds were yet distant from their young, and carrying fish in their bills, they would, on seeing a man, round to, drop their food, and perform the same evolutions. I, however, know nothing more remarkable of this species of Tern, than that it should breed, as I know from personal observation to be the case, along the whole of our Atlantic coast, in suitable places, from Texas to Labrador.

When travelling in stormy weather, they skim over the surface of the water, moving rapidly and close together; whereas in fine weather, they rise high, and proceed in a straggling manner. Now and then I have seen them alight among Tringas of different species, as well as among Razor-billed Shearwaters, on outward sand beaches.

GREAT TERN, Sterna Hirundo, Wils. Amer. Orn., vol. viii. p. 76.
STERNA HIRUNDO, Bonap. Syn., p. 354.
STERNA HIRUNDO, Great Tern, Swains. and Rich. F. Bor. Amer., vol. ii.p. 412.
GREAT or COMMON TERN, Nutt. Man., vol. ii. p. 271.

COMMON TERN, Sterna Hirundo, Aud. Orn. Biog., vol. iv. p. 74.

Male, 16, 31 1/2.

Breeds from Galveston Island along the shores of the Atlantic to Labrador, and as far north as lat. 57 degrees. Returns southward in autumn, passing beyond Texas. Extremely abundant.

Adult Male.

Bill about the same length as the head, rather slender, compressed, nearly straight, tapering to a narrow point. Upper mandible with the dorsal line slightly arched, the ridge rather broad and convex at the base, narrow towards the end, the sides sloping, convex towards the end, the edges sharp and inflected, the tip very slender. Nasal groove rather long, and with a faint groove and ridge extending obliquely to the edge of the mandible; nostrils sub-basal, linear, direct, pervious. Lower mandible with the angle very narrow, extending beyond the middle, the dorsal line straight, the sides ascending and convex, the edges sharp and inflected, the tip very acute.

Head of moderate size, oblong; neck of moderate length; body very slender. Feet very small; tibia bare for a considerable space; tarsus very short, slender, compressed, covered anteriorly with twenty-two small scutella, laterally and behind with reticular scales; toes very small, slender, the first extremely small, the third longest, the fourth considerably shorter, the second shorter than the fourth in the same proportion; the anterior toes connected by reticulated webs, which are deeply concave at their margin. Claws arched, compressed, that of the hind toe smallest, of the middle by much the largest, and having the inner edge thin and dilated.

Plumage soft, close, blended, very short on the fore part of the head; the feathers, in general, broad and rounded; wings very long, narrow, and pointed; primary quills tapering to a rounded point, slightly curved inwards, the first longest, the rest rapidly graduated; secondary quills short, broad, incurved, obliquely rounded, the inner more tapering. Tail long, very deeply forked, of twelve feathers, of which the outer are tapering, the middle short and rounded.

Bill bright coral-red, black towards the end, the tip light yellow; inside of mouth reddish-orange; eye hazel. Feet coral-red, lighter than the bill; claws brownish-black. Upper part of the head, and the hind neck half-way down, deep black, the anterior part tinged with brown, the posterior with blue. The sides of the head, the fore neck, and all the lower parts, white, with a slight tinge of greyish-blue on the breast. Back, scapulars, and wings, light greyish-blue, the edges of the wings, the rump, and upper tail-coverts, white, slightly tinged with grey. First primary with the outer web deep black, the shaft white, on the inner web a greyish-black band running along the shaft, narrow at the base, and widening so as to occupy the whole breadth of the web for an inch at the end, where it is hoary. The next five have the outer web, and a varying portion of the inner, in nearly their whole length hoary, but at the same time with a dusky shade, which becomes more apparent at the ends; the rest of the quills are like the back, but margined and tipped with white. Tail-feathers with the inner webs white, the outer webs of the colour of the back, paler on the middle feathers, gradually deepening outwards, and on the outer feathers dark or blackish-grey.

Length to end of tail 16 inches, to the fork of the tail 11, to end of wings 15 3/8, to end of claws 11 1/4; extent of wings 31 1/2; wing from flexure 11 3/12; tail to end of lateral feathers 7 1/12, to fork 3 1/12; bare part of tibia (6 1/2)/12; tarsus (10 1/2)/12; hind toe and claw (3 1/4)/12, middle toe and claw 1 1/12. Weight 5 oz.

The Female is similar to the male, but rather smaller. In some instances I have seen a small portion of the forehead white.

Length to end of tail 15 inches, to the fork 11 1/2, to end of wings 15 1/4, to end of claws 11; extent of wings 30 1/4; wing from flexure 10 1/2. Weight 5 oz.

The Young in their first plumage have the bill dull greenish-black, with the tip yellowish; the feet greenish-yellow.

In winter, the bill is black, with the base pale orange, and the tip yellowish; the feet orange-yellow. The colours are as in the adult, the forehead white, the rest of the head dusky, the upper parts having the feathers slightly margined with lighter.

Length to end of tail 12 3/4, to the fork 11; to end of wings 14, to end of claws 10 1/2; extent of wings 29 1/4; wing from flexure 8 1/4.

American and British specimens present no essential differences when compared in considerable numbers. The outer web of the lateral tail-feather is blackish-grey, and the inner webs of the tail-feathers are white in all the specimens collected for comparison. The tarsus in American specimens varies in length from 9 to 10 1/2 twelfths, and the claw of the middle toe from 2 1/2 to 4 1/2 twelfths; but similar differences are observed in the British birds.

The tongue is 1 4/12 inches long, sagittate and papillate at the base, very slender, tapering, the point slit, the upper surface a little concave, the lower horny towards the end. Aperture of posterior nares linear, 9 twelfths long. Palate with a middle and two lateral ridges. OEsophagus 6 inches long, extremely wide, its average diameter on the neck 7 twelfths, within the thorax 11 twelfths. The stomach is muscular, 1 inch long, the lateral muscles not distinguishable, the fasciculi of fibres being disposed as in the rapacious birds; the central tendinous spaces 3 twelfths in diameter; the cuticular lining strong, with broad longitudinal rugae. The contents of the stomach, fishes. The proventriculus 1 inch long. Intestine 1 foot 7 inches long, of moderate diameter, convoluted, varying from 2 3/4 twelfths to 2 1/2 twelfths. Rectum 1 inch long. Coeca 5 twelfths long, with a diameter of 3/4 of a twelfth.

The trachea is 3 1/4 inches long, 2 1/2 twelfths in breadth above, 1 1/2 twelfths below; its rings 103, feeble and unossified; the lateral muscles extremely slender; there are sterno-tracheal muscles, but none besides. Bronchial half-rings about 18.

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