46 ROUTES OF MIGRATION 



Most birds appear to return to their summer homes over much the 

 same route by which they left them. There are, however, a few marked 

 exceptions to this rule. Among our land-birds, the Connecticut War- 

 bler enters the United States through Florida and journeys thence 

 northwestward along the Alleghanies, and west to Missouri, to the 

 Upper Mississippi Valley and Manitoba. At this season it is unknown 

 on the Atlantic Coast north of Florida; but during its return migration, 

 in September and October, it is often not uncommon from Massachu- 

 setts southward and, at this season, is rare or unknown in the Missis- 

 sippi Valley south of Chicago. (See Cooke, '04.) 



Among our water-birds, cases of this kind are more frequent. The 

 fall migration often brings to the Atlantic Coast species which are 

 rarely if ever seen there in the spring. The Black Tern, for example, 

 occurs near New York City in numbers, from August to October, but 

 is not found there in the spring. 



The Golden Plover, as has been shown by Cooke ('93), after breed- 

 ing in June on the shores of the Arctic Ocean, in August migrates 

 southeastward to Labrador, where it feeds on the crowberry (Em- 

 petrum), laying on a supply of fat as fuel for the remarkable voyage 

 which follows. From Labrador the birds fly south to Nova Scotia 

 and thence lay their course for northern South America in a direct 

 line across the Atlantic. 



Under favorable conditions they may pass the Bermudas without 

 stopping, but should they encounter storms they rest in these islands 

 and are also driven to our coast. Their first stop may be made in 

 the Lesser Antilles, through or over which they proceed to South 

 America, en route to their winter quarters in southwestern Brazil and 

 the La Plata region. 



In returning to their Arctic home these Plover pass northward 

 through Central America and the Mississippi Valley, the main line 

 of their fall and spring routes, therefore, being separated by as much as 

 1,500 miles. 



The explanations advanced to account for the gradual develop- 

 ment of migration routes, over which birds in the fall retrace the path 

 followed in the spring, are inadequate to account for the origin of 

 these phenomenal journeys, on which the pioneer voyagers must 

 apparantly have embarked unguided by either inherited or acquired 

 experience. Nor do we understand how birds have learned to cross 

 regularly over bodies of water, hundreds or even thousands of miles 

 in width. 



European birds cross the Mediterranean, to and from Africa, at 

 a point where soundings indicate that a much closer land relation 

 formerly existed; but the 400-mile flight from Jamaica to northern 

 South America, the 600-mile flight from the nearest land to the Ber- 

 mudas, or the journey regularly made by the Turnstone and Golden 

 Plover to Hawaii, 2,000 miles from the nearest land, are evidently 

 not to be explained in this way. 



