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Waterfowl distribution is related to agricultural practices, urbanization, hunting pressure, sanctuary areas, and artificial feeding. The Cessna Skymaster's fast speed undoubtedly reduces survey efficiency through missed birds, but a slower-moving, noisier aircraft (Beaver) gives waterfowl more warning and may cause birds to flush so far in advance that they will be missed or misidentified. Most waterfowl seen were diving ducks. Of these, the bay ducks (Aythya spp.), common goldeneye (Bucephala clangula), bufflehead (Bucephala albeola), and mergansers (Mergus spp.) were excellent subjects for aerial survey because of their tendency to form highly visible flocks, preference for shallow water, and relatively minor avoidance reactions to low-flying aircraft. Long-tailed ducks (Clangula hyemalis) often dove before the aircraft reached them, further lowering counts. Boat traffic will tend to disturb rafting birds and thus reduce feeding efficiency. Only in the case of winter traffic of freighters and ice breakers might any benefits accrue to ducks from boat traffic proposed for the Seaway.