MIGRATIONS OF WATERFOWL 



flying or swimming about, often in great flocks . . . One may pass from the 

 blue water of the Stream, with floating gulf weed (Sargassum), and perhaps 

 here and there the iridescent float of a Portuguese man-of-war, into the 

 gray-green water of the Arctic Current with its thousands of jelly fish, and 

 in a few hours back again into the Stream. Each time, at the margin, one is 

 likely to see the surface display of that great abundance of life which has 

 made the Grand Banks one of the great fisheries of the world." 



Preston (1949) points to cloud formations as being constant during some 

 periods of the year, hence possible cues to ocean travelers. He utters "a word 

 of warning against the assumption that the ocean is featureless, merely be- 

 cause it is so shown on a map." Since we men do perceive some of this vari- 

 ety in the oceanic world, it is within reason to believe that the bird, so much 

 closer to its wild environment, is aware of these things. Sutton (1934) 

 speaks of the "Sheenah-cloud" of the North, "a gray cloud that gathers over 

 open water at the ice-edge." This is a guide to the native Eskimo; it might 

 be a cue for birds. Wetmore (1926) points out that the green lagoon water 

 of reefed atolls throws a reflection high above that may be visible before the 

 land itself is seen. Heyerdahl (1950) likewise speaks of this, saying that "as 

 the sun rose straight up over the sky astern of us we could see a clear green 

 glimmer high up towards the misty sky over the island. It was the reflection 

 of the still, green lagoon on the inside of the surrounding reef. Some of the 

 low atolls throw up mirages of this kind for many thousand feet into the air, 

 so that they show their position to primitive seafarers many days before the 

 island itself is visible from the horizon." 



Heyerdahl also writes of the island cloud cap which identifies land long 

 before it is seen. "With each day that passed, larger flocks of sea birds came 

 and circled over us aimlessly in all directions. One evening, when the sun 

 was about to sink into the sea, we noticed that the birds had received a 

 violent impetus. They were flying away in a westerly direction without pay- 

 ing any attention to us or the flying fish beneath them. From the mast we 



