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.