In the twilight hours of early summer evenings, bands of drakes may be 

 seen arriving at Delta, usually from the northwest. 



like the ducks and the Coot, are flightless during the wing-molt, there is a 

 shift away from small breeding marshes to larger waters. At Delta the large 

 Western Grebe, which nests in the marsh, moves to the open waters of Lake 

 Manitoba, where the wing-molt takes place. 



In a great many birds which, unlike the ducks, coots, and grebes, molt 

 the wing feathers gradually and are not flightless, there is, nevertheless, a 

 regular postbreeding transfer which involves a large portion of the adult 

 population. Some of these, like the Tree Swallow and the Bank Swallow, 

 have a postbreeding shift that carries them annually to the same traditional 

 stopping places. Thus in the first week in July, Tree Swallows reach Delta 

 to gather in great numbers on pen wires or on trees which, used year after 

 year, have long ago been killed by the excrement. So, too, some shore birds 

 and blackbirds gather at Delta in late June or early July. The first arrivals 

 are adults, possibly nonbreeders or birds thwarted in their nesting attempts. 

 But later on the old birds are joined by young, so that by the time the mass 



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