Some of the common summer residents are not content with a trip to northern South America, but push on across the Equator and finally come to rest for the winter in the pampas of Argentina, or even in Patagonia. Thus some species that are more or less associated with, each other in summer, as nighthawks, barn swallows, cliff swallows, and some of the thrushes may also occupy the same general winter quarters in Brazil. Some individual nighthawks and barn swallows (fig. 13) travel still farther, and of all North American land birds these species probably have the longest migration route, as they occur north to Yukon and Alaska, and south to Argentina, 7,000 miles away. Such seasonal flights are exceeded in length, however, by the journeys of several species of water birds, chiefly members of the suborder of shore birds. In this group are 19 species that breed north of the Arctic Circle and winter in South America, 6 of them going as far south as Patagonia, and thus having a migration route more than 8,000 miles in length. [Illustration: B1035M Figure 14.--Arctic tern. The longest flight known for an individual bird was accomplished by an arctic tern that in 3 months flew from the coast of Labrador to the coast of southeastern Africa.] The arctic tern (_Sterna paradisaea_) is the champion "globe trotter" and long-distance flier (figs. 14 and 15). Its name "arctic" is well earned, as its breeding range is circumpolar and it nests as far north as it can find a suitable place. The first nest to be found in this region was only 7½° from the North Pole, and it contained a downy chick surrounded by a wall of newly-fallen snow that had been scooped out by the parent. In North America it breeds south in the interior to Great Slave Lake, and on the Atlantic coast to Massachusetts. After the young are grown, the arctic terns disappear from their North American breeding grounds, and a few months later they may be found in the Antarctic region, 11,000 miles away. Until very recently the route followed by these hardy fliers was a complete mystery, for although a few scattered individuals have been noted south as far as Long Island, the species is otherwise practically unknown along the Atantic coasts of North America and South America. It is, however, known as a migrant on the west coast of Europe and Africa. By means of numbered bands the picture is now developing of what is apparently not only the longest but also one of the most remarkable of all migratory journeys.