Figure 17. Distribution and migration of the redstart. An example of a wide migration route, birds of this species cross all parts of the Gulf of Mexico, or may travel from Florida to Cuba and through the Bahamas. Their route has an east-and-west width of more than 2,000 miles.
Principal Routes From North America
W. W. Cook presented seven of the more important generalized routes for birds leaving the United States on their way to various wintering grounds (1915a; [Fig. 18.]). When migrants return northward in the spring, they may follow these same routes, but it is not known for certain whether they do. These routes are discussed in the following sections.
Atlantic Oceanic Route
Route No. 1 ([Fig. 18.]) is almost entirely oceanic and passes directly over the Atlantic Ocean from Labrador and Nova Scotia to the Lesser Antilles, then through this group of small islands to the mainland of South America. Most of the adult eastern golden plovers and some other shorebirds use this as their fall route. As we mentioned previously, radar has indicated strong fall movements of warblers from the New England coast out over the Atlantic to points south along this route. Since it lies almost entirely over the sea, this route is definitely known only at its terminals and from occasional observations made on Bermuda and other islands in its course. Some of the shorebirds that breed on the Arctic tundra of the District of Mackenzie (Northwest Territories) and Alaska fly southeastward across Canada to the Atlantic coast and finally follow this oceanic route to the mainland of South America. The golden plover may accomplish the whole 2,400 miles without pause or rest, and in fair weather the flocks pass Bermuda and sometimes even the islands of the Antilles without stopping. Although most birds make their migratory flights either by day or by night, the golden plover in this remarkable journey flies both day and night. Since this plover swims lightly and easily, it may make a few short stops along the way.
Figure 18. Principal migration routes used by birds in passing from North America to winter quarters in the West Indies, Central America, and South America. Route 4 is the one used most extensively while only a few species make the 2,400 mile flight down Route 1 from Nova Scotia to South America.
The Arctic tern follows the Atlantic Ocean route chiefly along the eastern side of the ocean. Likewise, vast numbers of seabirds such as auks, murres, guillemots, phalaropes, jaegers, petrels, and shearwaters follow this over-water route from breeding coasts and islands in the Northern and Southern Hemispheres.
Atlantic Coast Route and Tributaries