THE CYCLE OF MIGRATION 



without ducks in every corner of the sky. During the heaviest waves, fifty 

 or sixty flocks a minute may pass over a section of marsh a mile wide ; and 

 as far east and west as one can see, waterfowl cross over in steady numbers, 

 small bands and large. The stream of their passage seems endless ; then after 

 sundown the rosy twilight changes to cold blue, and the last ducks have 

 passed. Another autumn is gone. 



So ends the waterfowl year at Delta. The broad basin of Lake Manitoba 

 is the home of ducks from April until November frost. There they move to 

 and from their feeding and loafing places, between territory and nest, from 

 lakeshore to stubble and return. Day upon day is built the restless activity 

 of living. The daily chain of travel carries them back and forth across fami- 

 liar terrain. Then suddenly all this is abandoned. The winter is cold and 

 deep. The marsh is without waterfowl until the first hardy birds come back 

 in late March or early April. How do they find their way out of the harsh 

 northland? What guides them back with the soft winds of spring? These 

 are the questions eternal. 



Migration is the annually repeated cycle of travel that carries waterfowl 

 away from their birthplace or breeding grounds to temperate wintering 

 waters, returning them to the familiar homeland with the advent of spring. 

 It is important that we think of each migration as beginning and ending in 

 the region of natal experience, with the winter interlude in the south. In 

 the migrational history of a species, to be sure, we might properly consider 

 the impetus as coming from the south, the annual cycle carrying a species 

 to and from its breeding place. For the individual bird, however, the home 

 range on the breeding ground is the start of all migratory movement; and 

 this very same place is the final goal which must be attained to complete the 

 annual cycle. Mayr (1942:240) says that the tendency of birds to return to 



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