The annual flight of adult golden plovers is so unusual, it will be given in some detail. The species is observed by hundreds of bird watchers every year and it well illustrates loop migration (Fig. 24). [Illustration: _Figure 24. Distribution and migration of the American golden plover. Adults of the eastern subspecies migrate across northeastern Canada and then by a nonstop flight reach South America. In spring they return by way of the Mississippi Valley. Their entire route, therefore, is in the form of a great ellipse with a major axis of 8,000 miles and a minor axis of about 2,000 miles. The western subspecies migrates across the Pacific Ocean to various localities including the Hawaiian and Marquesas islands and the Low Archipelago._] In the fall, the birds fatten on the multitude of berries along the coasts of Labrador and Nova Scotia, then depart south over the Atlantic Ocean to South America. After reaching the South American coast the birds make a short stop, then continue overland to the pampas of Argentina, where they remain from September to March. When these golden plovers leave their winter quarters they cross northwestern South America and the Gulf of Mexico to reach the North American mainland on the coasts of Texas and Louisiana. Thence they proceed slowly up the Mississippi Valley and, by the early part of June, are again on their breeding grounds, having performed a round-trip journey in the form of an enormous ellipse with the minor axis about 2,000 miles and the major axis 8,000 miles stretching from the Arctic tundra to the pampas of Argentina. The older birds may be accompanied by some of the young, but most of the immature birds leave their natal grounds late in summer and move southward through the interior of the country, returning in spring over essentially the same course. The oceanic route is therefore used chiefly by adult birds. A return by the oceanic route in the spring could be fatal. The maritime climate in the Northeast results in foggy conditions along the coast and the frozen soil would offer few rewards for the weary travelers. By traveling up the middle of the continent, a much better food supply is assured (Welty 1962).