"Memory is the vehicle of duration." Will Durant, 

 The Story of Philosophy 



The Function of Memory 



The ducks of the Delta Marsh move familiarly 

 within an environment they have learned. Some have been hatched there, 

 learning their place in ever increasing spans. Others have been reared else- 

 where, arriving at Delta in summer or fall. When flying from one place to 

 another for feed, rest, or grit, these residents travel over country that is 

 familiar through the experience of use; but no matter how broad or narrow 

 the local experience, there must always come a time for departure from the 

 northland. Some juveniles disperse from their natal range soon after taking 

 wing. After the midsummer molt, many males leave for other places. By 

 late August the southward migration is in full swing, with the Blue-winged 

 Teal leading the parade. Successive flights bring a constant turnover of ar- 

 rivals and departures until finally, when November ice covers the bays, all 

 waterfowl migrate southward. They are gone from Delta for five months. 

 Some, such as the Blue-winged Teal, are away even longer. Most bluewings 

 have left by the first week of October and they do not return until late 

 April, an absence of nearly seven months. 



When spring brings these wildfowl back from the wintering grounds, 

 we know that many return to their old haunts. Sowls's study (1949) of 

 marked females leaves little doubt of the close tie between the breeding hen 

 and her nesting locality. Not only does she come back to her marsh, but fre- 

 quently to the same meadow where she had nested previously. Sowls (1955) 

 also showed how young females return home after their first migration. 

 Regional fidelity is further suggested in banding records such as those of 

 Sullivan (1953), who captured a Canvasback hen and brood at his lodge on 

 the Libau Marsh. Four years later a hunter shot the mother less than a mile 

 from the place of original capture. While many drakes do not make a direct 

 spring return to their native marsh, banding studies suggest that, after the 

 breeding period is ended, they often revisit familiar places. 



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