MIGRATIONS OF WATERFOWL 



the same place for reproduction year after year "has been proven by so 

 many studies that it would be unfair to single out a particular one"; and 

 Valikangas ( 1933 ) , in his classic experiment, showed how the young of wild 

 ducks were tied to the region of birth. He brought eggs of English Mallards 

 to Finland, where they were hatched and where the young were raised and 

 given migratory freedom. Of 62 birds released, 34 came back to their Fin- 

 land home after their first trip to the wintering grounds. 



Sowls (1949, 1950, 1951, 1955) has presented much evidence to show the 

 fidelity of the female to her nesting marsh, his experiments demonstrating 

 that she returns to nest not only in the same meadow, but often in the same 

 part of that field. After studying five species * intensively by following the 

 individual histories of nest-trapped, color-marked hens, he concluded that 

 "they normally return to the original nesting meadow a second and a third 

 and a fourth year, or so long as they survive and the area remains suitable." 

 He also found a remarkable return of young females to the home marsh 

 after their first migration. Of 115 juvenile Pintail hens, for example, 13 per 

 cent came back to Delta to be individually recorded ( by leg bands ) on the 

 small pond where they were raised. Sowls discovered the nests of 8 of these 

 young females only a short distance from the birthplace. Winter matings in 

 the large aggregations of the southland sometimes join the drake to a fe- 

 male from a region unfamiliar to him and he cannot go to his own home. 

 Thomson (1931, 1945) has given the term "abmigration" to movements, 

 such as those of winter-mated drakes, where a bird native to one region is 

 "found in a subsequent summer in quite a different area." Banding evi- 

 dence presented by Sowls (1951) and Cartwright (1952) indicates, how- 

 ever, that such males may come back to familiar places, sometimes the 

 natal marsh, after their marital duties are finished. 



If we accept the homeland of birth and breeding to be the start and 

 finish of the annual migration cycle, it is clear that a duck travels away from 

 a region of learned experience and returns to a familiar range. However 

 mysterious the act of departure, by whatever guidance it finds its way back, 

 the familiar home is the start and the finish of each individual's migration ; 

 the beginning and ending of the annual migration is a learned place. 



While the tie to home holds for all waterfowl, we must recognize im- 

 portant differences in migrational behavior between geese and swans on 

 the one hand and ducks on the other. In the former there is a strong family 

 bond, parents and children remaining together during southward migration. 



• Mallard, Pintail, Gadwall, Blue-winged Teal, Shoveller. 



92 



