Mallard 
The mallard (Anas platyrhynchos) has traditionally been 
mainly a Mississippi Flyway duck, but populations tend to spill 
over to other Flyways. Mallard population trends in the Bay are 
similar to those of the black duck (Table 1? Fig. 3). Mallard 
populations in the Chesapeake Bay were lowest in the late 1940s 
and early 1950s, with a low count in 1949 (8,235). Excellent 
breeding conditions in the prairie provinces of Canada in the 
mid-1950s caused populations to rise, and a peak wintering 
population in the Chesapeake Bay occurred in 1956 (182,195). 
Drought conditions in the late 1950s and early 1960s caused 
populations to decrease and to remain relatively low and stable 
throughout the 1970s. 
In the mid-1970s large numbers of game-farm mallards were 
released in the Chesapeake Bay with releases continuing through¬ 
out the 1980s. The release program is probably a major reason 
that mallard numbers in the Chesapeake Bay were 16% higher 
during the 1980s (57,553) than the pre-1980 average (49,826). 
Many of these game-farm mallards are found in close association 
with man, and appear to adapt to changing environmental 
conditions more readily than the closely related black duck. 
Mallards were more numerous than black ducks in the Chesapeake 
Bay during eight of the last ten years (1977-86). The long-term 
average population of mallards in the Chesapeake Bay was 51,212. 
Stewart (1962) found that seeds of smartweeds, bulrushes 
(Scirpus spp.), and burreed (Sparganium americana) predominated 
in the mallard diet in fresh water areas. In brackish areas, 
seeds, leaves, and stems of SAV were more important as food 
sources. Rawls (1978) found SAV as the predominant food during 
the 1960s, whereas, Munro and Perry (1981) found only 5% of the 
food eaten by mallards was SAV during the 1970s. Seeds of a 
variety of marsh plants (over 100) were the predominant foods. 
Wigeon 
Wigeon (Anas americana) populations in the Chesapeake Bay 
declined during the years of aerial surveys (Table 1; Fig. 4). 
Peak populations occurred in 1955 (144,350), most likely due to 
excellent production in the breeding provinces of Canada. 
Wigeon numbers declined to a low of only 900 ducks in 1984. The 
long-term average winter population was 29,246. During the 
1980s the winter population has averaged only 5,226 ducks, which 
was 85% lower than the pre-1980s average of 34,500. Population 
declines of wigeon in the Chesapeake Bay have occurred at a 
faster rate than those in the Atlantic Flyway and in North 
America. 
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