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Only a few diving ducks, including redhead, ruddy, and canvasback, 
continue to nest in lowa. These species are so few in number that no attempt has 
been made to evaluate their production trend. Adult lesser scaup have remained 
in northwest lowa throughout the nesting season, but no nests, broods, nor young 
have been observed. Nesting attempts of ring-necked duck have been reported 
during the last few years, but like the lesser scaup no evidence of successful 
nesting has been witnessed. A few pintails, shovelers, and gadwall nest in the 
State, but too few to indicate a trend. In 1955 a few baldpate have likewise been 
observed. 
Special emphasis has been placed upon the study of the wood duck 
because it has again become an important nester during the last 15 years, and 
lowa's contribution to the over-all production of this species is important within 
the flyway. In 1954 and 1955 both stream survey data and wood duck nesting box 
checks indicated reduced breeding populations of wood ducks within the State. 
(Tables I and LI.) 
The productive potential of the wood duck in Iowa is not well under- 
stood, nor is the size of the standing crop. The nesting density of this species 
and its range throughout the State has increased during the last 10 years, but it 
is probable that 1949 or 1950 may have been peak years for wood duck production, 
and that the trend since then has been downward. Many wood ducks harvested in 
lowa are probably young birds produced within the State or in neighboring States. 
The harvest of the past season may be a partial indicator of past production and 
in some measure indicative of current breeding stock remaining. It is note- 
worthy that when the waterfowl season has opened in Iowa on October 20 or later, 
that the removal of potential breeding stock has been reduced roughly one-third 
Or more in Iowa. (Table IIL.) 
