"Treacherous in calm, and terrible in storm, 

 Who shall put forth on thee, 

 Unfathomable Sea?" Percy Bysshe Shelley 



13 

 Overseas Migration 



It is one thing to measure the flight of a duck 

 from Delta, Manitoba, to Lake Christina, Minnesota, and yet quite another to 

 appraise the migration of Pintail, Shoveller, and other waterfowl from North 

 America to the Hawaiian Islands. The shortest distance to the first landfall 

 is at least 2,000 miles over the unbroken ocean, a passage equal to a flight 

 from Delta to central Mexico. The first step in studying such overseas migra- 

 tions is to quantify the flight distance in terms relative to the movement of 

 man, the puzzled observer. In doing this it is only fair to use the most con- 

 servative combination of travel coordinates. Canvasback and other ducks 

 have been seen migrating overland at Delta at ground speeds of 60 miles 

 per hour, and faster; but on the open Pacific, Buss (1946) timed Pintails 

 at approximately 33 m.p.h. At this rate of travel Pintails might cover the 

 2,000 miles from the Aleutians to the Hawaiian Islands in 60 hours of flight, 

 which in relative terms is comparable to a journey of 240 miles for a man 

 going at a speed of 4 m.p.h. ( Figure 24) . 



The Hawaiian Archipelago, as Griffin and Hock (1949) point out, 

 spreads over 1,600 miles of the Pacific, from Hawaii to Midway, while the 

 knot of major islands is about 400 miles across. It is thus obvious that mi- 

 grants are not obliged to navigate precisely to a pinpoint in the middle of 

 the vast Pacific. Wide errors in course could be allowed and still permit a 

 landfall upon one part or another of the archipelago, from which travel to 

 the exact place of previous experience might be made over much lesser 

 stretches of open water. With relative values of height and breadth of travel 

 not differing greatly for man and bird, the problem fairly stated is directly 

 comparable to that involved in a man's journey at 4 m.p.h. going 240 miles 

 toward a region that has a total width of about 190 miles. 



177 



