MIGRATIONS OF WATERFOWL 



trackless monotony." Yeagley (1947) concluded that "since there are no 

 'sign posts' of any kind over the ocean wastes, the flights must involve true 

 navigation." 



Yet, however monotonous the seascape, every sailor knows that the 

 ocean is not wholly a region of sameness. Some of its variations, as where 

 currents meet, are nearly as stable and well marked as geologic formations 

 on land. There are differences in color, salinity, air and water temperatures, 

 plant and animal life, all to be perceived. There is a vast array of evidence 

 to show how the birds of the sea are aware of these variations even when 

 they are many miles beyond sight of shore. Murphy (1936:81) shows how 

 "currents affect every sort of life in at least the upper layers and, in turn, 

 exercise large control over the numbers and distribution of sea birds." Miller 

 (1940) tells how the Blackfooted Albatross off the coast of California con- 

 centrates its numbers over a cold "tongue" of ocean, apparently attracted 

 there by the abundant food. Carson ( 1951 ) describes the response of some 

 birds to the movements of fish or plankton. "Capelin gather in the deep, 

 cold waters of the Barents Sea, their shoals followed and preyed upon by 

 flocks of auks, fulmars and kitiwicks . . . Out over the plankton meadows 

 of the North Atlantic the dry twitter of phalaropes, small brown birds, 

 wheeling and turning, dipping and rising, is heard for the first time since 

 early spring. The phalaropes have nested on the arctic tundras, reared their 

 young, and now the first of them are returning to the sea. Most of them will 

 continue south over the open water far from land, crossing the equator into 

 the South Atlantic. Here they will follow where the whales lead, for where 

 the whales are, there also are swarms of plankton on which these strange 

 birds grow fat." 



The border of the Gulf Stream is obvious to the most casual eye; the 

 water is drab green on one side, richly blue on the other. "The dark blue 

 water of the open sea far from land is the color of emptiness and barren- 

 ness," writes Carson ( 1951 ) ; "the green water of the coastal areas, with all 

 its varying hues, is the color of life. The sea is blue because the sunlight is 

 reflected back to our eyes from the water molecules or from very minute 

 particles suspended in the sea. In the journey of the light rays downward 

 into the water and back to our eyes, all the red rays of the spectrum and 

 most of the yellow have been absorbed, so it is chiefly the cool, blue light 

 that we see. Where the water is rich in plankton, it loses the glassy trans- 

 parency that permits this deep penetration of the light rays. The yellow 

 and brown and green hues of the coastal waters are derived from the minute 



180 



