OVERSEAS MIGRATION 



could see that, as they came over, they flew straight on exactly the same 

 course . . . We twisted the steering gear and set our course exactly in the 

 direction in which the birds had disappeared. Even after it was dark, we 

 heard the cries of stragglers flying over us against the starry sky on the same 

 course as that which we were following . . . Next day there were still 

 more birds over us, but we did not wait for them to show us our way again 

 in the evening. This time we had detected a curious stationary cloud above 

 the horizon. The other clouds were small feathery wisps of wool which 

 came up in the south and passed across the vault of the sky with the trade 

 wind until they disappeared over the horizon to the west . . . But the 

 lonely cloud on the horizon to the southwest did not move; it just rose like 

 a motionless column of smoke while the trade winds drifted by. The Poly- 

 nesians knew land lay under such clouds. For, when the tropical sun bakes 

 the hot sand, a stream of warm air is created which rises and causes its 

 vapor to condense up a colder stratum of air." 



One might go on for many more pages, drawing from the literature of 

 the sea a strong document, evidencing its variation in the eyes of man. 

 Aware of these characters as we are, we still are not birds. Much more close- 

 ly in tune with their environment, they may be far more keenly perceptive 

 of environmental cues than we men. 



If the height of overseas travel is truly lower than for overland migra- 

 tions, I feel there must be good reasons why birds, such as ducks, reduce 

 their height of travel. There are exceptions, to be sure, especially as ocean 

 travelers start their journeys. Deelder (1949), for example, observed a 

 tendency for the Chaffinch to increase its altitude when going out to sea. 

 Henshaw ( 1910 ) gives evidence that the Pacific Golden Plover may rise to 

 great heights in its departure from the Hawaiian Islands. By and large, 

 however, the evidence in the literature suggests the regularity of low ocean 

 crossings. Wetmore (1926), for example, says that he has "observed autumn 

 flights of sandpipers crossing the Gulf of Alaska, south of Kodiak Island 

 and the Kenai Peninsula, at heights of not more than 500 feet above the sea, 

 with many at only a few yards above the waves. In fact, a Peale's falcon 

 remained with our ship for a day, perching on a masthead and flying out at 

 intervals to seize some poor sandpiper that came swinging up to examine 

 our vessel. . . . Numerous recorders of migrants crossing stretches of open 

 water note them frequently as passing barely above the waves." 



In flying just above the water surface, migrants going into the wind 

 might benefit as the air current is slowed by friction with the sea; and, as 



183 



