The Common Terns arrive in the south of Europe early in May, and progressing northwards, colonising as they go, visit Ireland, Scotland, and some of the adjacent islands. On inland waters the Terns do not congregate in great numbers. On the sea-shore, on the contrary, as the breeding season approaches, hundreds of them collect together and form large settlements. One of these settlements, on the coast of one of the Canary Islands, was visited by Bolle, who gives the following account of what he saw:--"The farther we advanced the more numerous became the flights of such pairs as we had disturbed, until at length we were obliged to proceed carefully to avoid treading on their eggs, so numerously did they lay around us on every side. Scarcely had we begun to collect some of the eggs in our hats and baskets, than up rose the whole multitude of breeding birds into the air, thousands in number, and overshadowed us like a great white cloud. Their shrieks were positively deafening, and the uproar was still further increased by the appearance of some other men at a little distance, who were likewise collecting eggs. From out of the living screen above us, many of these birds seemed to rush right down upon our heads, and these were probably those whose nests lay nearest to the place where we stood, and were consequently in the greatest danger of being plundered. After a little while, we retired to a distance, whence we could plainly see the different pairs, as they returned to their eggs, upon which the females immediately planted themselves, while their faithful spouses took their stations beside them. We did not leave them, however, till we had completely filled all our baskets with eggs, and this we accomplished in less than an hour. The men above alluded to, informed us that for a few weeks in the year, the place was constantly resorted to by the inhabitants, who eagerly collected the eggs, and that, nevertheless, the number of birds did not seem to diminish; the truth of this last assertion was indeed sufficiently evident." It not unfrequently happens that by some sudden flood in the rivers, or heavy storm at sea, the breeding-places of these Terns are completely inundated, and their eggs consequently destroyed. Should such an event occur early in the season, the parent birds will produce a second brood, but if it happens at a later period, their hope of progeny is at an end. Upon one occasion Naumann had an opportunity of witnessing a fair chase between the Common Tern and the agile Tree Falcon. The Tern did not put into execution any of the usual manœuvres of water-birds, when trying to escape from pursuit, such as diving below the surface, but took boldly to her wings, and it was truly wonderful to see the adroitness with which all the efforts of the Falcon were foiled; whenever this terrible bird of prey stooped upon his intended victim, she slipped nimbly aside, and thus eluded the fatal