Referring again to figure 20, it is noted that route no. 3 presents a much more direct line of flight for the Atlantic coast migrants to South America than the others, although it involves much longer flights. It is used almost entirely by land birds. After taking off from the coast of Florida the migrants find only two land masses on the way where they can pause for rest and food. Nevertheless, tens of thousands of birds of some 60 species cross the 150 miles from Florida to Cuba, where about half of them elect to remain for the winter. The others fly the 90 miles between Cuba and Jamaica. From that point to the South American coast, however, there is a stretch of unbroken ocean fully 500 miles across, and scarcely a third of the North American migrants leave the forested mountains of Jamaica to risk the perils of this ocean trip. Chief among those that do is the bobolink (_Dolichonyx oryzivorus_), which so far outnumbers all other birds using this fly way that route no. 3 may well be called "the bobolink route" (fig. 23). As traveling companions along this route the bobolinks may meet vireos, kingbirds, and nighthawks from Florida; the chuck-will's-widow (_Antrostomus carolinensis_) of the Southeastern States; black-billed and yellow-billed cuckoos (_Coccyzus erythropthalmus_ and _C. americanus_) from New England; gray-cheeked thrushes from Quebec, bank swallows (_Riparia riparia_) from Labrador; and blackpoll warblers from Alaska. Sometimes this scattered assemblage will be joined by a tanager or a wood thrush but "the bobolink route" is not popular with the greater number of migrants, and although many individuals traverse it, they are only a small fraction of the multitudes of North American birds that spend the winter in South America. MACKENZIE VALLEY-GREAT LAKES-MISSISSIPPI VALLEY ROUTE AND TRIBUTARIES Easily the longest flyway of any in the Western Hemisphere is that extending from the Mackenzie Valley past the Great Lakes and down the Mississippi River, including its tributaries. Its northern terminus is on the Arctic coast in the regions of Kotzebue Sound, Alaska, and the mouth of the Mackenzie River, while its southern end lies in Patagonia (fig. 21). During the spring migration some of the shore birds traverse the full extent of this great path, and it seems likely that the nighthawk, the barn swallow, the blackpoll warbler, and individuals of several other species that breed north to Yukon and Alaska must twice each year cover the larger part of it.