THE BLACK MARSH TERN.

The Black Marsh Tern (Hydrochelidon nigra) is of a deep rich black on the head, nape, breast, and centre of belly; the mantle is blueish grey, and the region of vent white. The wing-quills are dark grey bordered with a lighter shade, and the tail-feathers dark grey. The eye is brown, beak greyish black with red base, and foot brownish red. In the winter dress, only the back of the head and nape are black, the forehead and under part being white. In young birds the mantle-feathers and wing-covers are edged with reddish yellow. The length of this species is nine inches, span of wings twenty-six inches. The Black Tern inhabits the north temperate zone, and during the winter wanders so far south, that, like Sternula minuta, it is to be met with in four continents—Europe, Asia, Africa, and America. It makes its appearance in Great Britain at the same time as the other Terns, but is much less abundant than formerly, being seldom seen in the North of England and very rarely in Scotland, although it still visits many parts of Ireland. It arrives in this country about the end of April or beginning of May, and is principally found in Lincolnshire, Norfolk, and Cambridgeshire. In Montagu's time it was common in Romney Marsh, in Kent; specimens have also been procured in other southern counties. During their winter peregrinations these birds generally travel in companies varying from twenty to about a thousand individuals, following the course of the streams, and taking up a temporary residence wherever these spread out into extensive swamps or overflow the neighbouring land. In their deportment, food, and mode of breeding, they also differ materially from the Common Terns. They walk seldom, and as badly as their brethren, and rarely swim, as their powers in that respect are very limited. Their flight is not so rapid and devious as that of their congeners, but more even, gentle, and light. During the night season they betake themselves to repose, but in the daytime are constantly on the wing, hunting after food. The Black Terns live almost exclusively upon insects, although they will also occasionally seize a little fish or other small inhabitant of the water. They somewhat resemble the Swallows in their mode of life, and like them may be seen skimming over pools of water, apparently more for the sake of amusement than from any real necessity for such active exertion. When they discover anything in the shape of food, they hover over it for an instant and pounce upon their prey, not coming down upon it precipitately and perpendicularly as some of the Divers do, but sweeping obliquely towards it, so as to seize it with the beak without immersing their bodies. According to Montagu, "The flight of this species is not unlike that of the Goatsucker; its evolutions are rapid and it turns short if attacked, by which means it escapes the talons of predaceous birds, as we once had an opportunity of witnessing. In a very hard gale of wind many Terns were sporting over the water, when a Peregrine Falcon passed like a shot, singled out his bird and presently coming up with the chase, made a pounce, but the great dexterity of the Tern avoided the deadly stroke and took a new direction. The Falcon, by his superior velocity, soon regained sufficient elevation to successively repeat his pounces, but at last relinquished the pursuit." The Black Terns, unlike the generality of their congeners, are fearless and unsuspicious, and seem rather to welcome than to avoid the presence of mankind; if molested, however, they soon become more wary. Towards each other they manifest considerable affection, and should one of their party be shot, the others instantly collect around their wounded companion, not from any sinister motives, as has been asserted by some writers, but out of commiseration for his condition. For their breeding-places these birds invariably choose some wide swamp or morass, placing their nests upon little heaps of mud that project above the surface of the water, upon tufts of grass or sedge, upon floating masses of reeds, rushes, or similar materials, or sometimes on the floating leaves of aquatic plants. The nest itself is constructed of substances that vary with the locality selected, such as leaves, roots and rushes heaped carelessly together. In this cradle, about the beginning