[Illustration: COMMON TERN _Sterna fluviatilis_ Summer. Young flying] They nest in colonies on rocks, shingle beaches, or near the margins of large inland waters, and very little attempt at a nest is made, though this species almost invariably gathers a few bents together. The eggs are usually three in number, often only two, and are very variable in colour, being as a rule greenish or stone buff, with brown and grey spots and markings. The note is a sharp “kik-kik,” but during the nesting season they utter a loud “ee-arre,” which is rather characteristic of this species. The young are covered with pale brown down mottled with black, and leave the nest as soon as they are hatched, but they remain near the spot until they are fully fledged and well able to fly, as they are during that period entirely dependent on their parents for food. Soon after the young can fly, old and young gradually disperse along the coast, slowly working southwards till by the beginning of October the last straggler has left for its winter quarters in Africa. In summer the adult has the crown of the head and nape black, the rest of the back pearl-grey; rump white; tail feathers white with greyish outer webs. Under parts white tinged with grey. Bill orange red with _horn-coloured tip_; legs coral red. The sexes are alike. In winter the forehead is sprinkled with white and the under parts nearly pure white. The young in its first plumage has the head white; spotted with blackish brown, the feathers of the back pale pearl-grey barred with buff or brown and tipped with white; by late autumn, however, the back is pure grey with the exception of a dark band along the carpal joint. Bill and legs yellowish. Length 14·25 in.; bill 1·7 in.; tail 6·5 in.; wing 10·5 in. THE ARCTIC TERN Sterna macrura, Naumann Except in a few minor points of plumage and in its distribution this species is the counterpart of the preceding one. In England it is only met with on migration, though a few pairs may nest in the north, but in Scotland it is the commonest Tern, breeding in increasing numbers northwards. In Ireland it breeds commonly, especially on the wind-swept islets of the north and west. Elsewhere it breeds in circumpolar regions, and has been met with in winter in Antarctic seas, so that it has a latitudinal range of from 82° N. to 74° S., probably the largest range recorded for any one species. Its nesting habits are similar to those of the Common Tern, and as a rule it collects absolutely no materials for a lining, but lays its eggs in a shallow “scrape” or even on the bare rock. The eggs are indistinguishable in colour from those of the Common Tern, but are on the average slightly smaller. To the experienced ear the note is also rather different, but that difference is too slight to be expressed on paper.