BIRD MIGRATION. 21 



ECCENTRIC MIGRATION ROUTES. 



The normal migration route for the birds of eastern North America 

 is a northeast and southwest course approximately parallel with the 

 trend of the Atlantic coast; the birds breeding in the interior take a 

 line of flight parallel in general with the course of the three great 

 river valleys — those of the Mississippi, the Red, and the Mackenzie 

 that form a highway rich in food supplies between their winter and 

 summer homes. Many birds, however, follow migration routes 

 widely differing from the normal. One of the most extreme excep- 

 tions is that of the marbled godwit. Formerly a common breeder 

 in North Dakota and Saskatchewan, some individuals on starting 

 for their winter home in Central America took a course almost due 

 east to the Maritime Provinces of Canada and thence followed the 

 Atlantic coast to Florida and continued southward; others went in 

 the opposite direction, traveling westward to southern Alaska and 

 southward along the Pacific coast to Guatemala. Thus birds which 

 were near neighbors in summer became separated nearly 3,000 miles 

 during migration, to settle finally in close proximity for the winter. 



The Connecticut warbler, choosing another eccentric course, adopts 

 different routes for its southward and northward journeys (see fig. 7). 

 All the individuals of this species winter in South America, and so 

 far as known all go and come by the same direct route between 

 Florida and South America across the West Indies; but north of 

 Florida the spring and fall routes diverge. The spring route leads 

 the birds up the Mississippi Valley to their summer home in southern 

 Canada; but fall migration begins with a 1,000-mile trip almost due 

 east to New England, whence the coast is followed southwest to 

 Florida. The Connecticut warbler is considered rare, but the multi- 

 tudes that have struck Long Island lighthouses during October 

 storms show that the species is at least more common than would 

 be judged from spring observations, and also how closely it follows 

 the coast line during fall migration. The breeding of the Connecticut 

 warbler offers a fruitful field of investigation for some bird lover 

 during a summer vacation, for there undoubtedly is a large and as 

 yet undiscovered breeding area in Ontario north of Lakes Huron and 

 Superior. Incidentally this route of the Connecticut warbler is a 

 conclusive argument against the theory that migration routes always 

 indicate the original pioneer path by which the birds invaded the 

 region of their present summer homes. 



Another species having an elliptical migration route is the white- 

 winged scoter (fig. 8 and PL III). This duck breeds near fresh water 

 in the interior of Canada and winters entirely on the ocean along the 

 Atlantic and Pacific coasts of the United States. From its summer 

 home west of Hudson Bay individuals that are to winter on the 

 Atlantic travel 1,500 miles almost due east to the coast of the most 



