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resulted from optimum water levels, excellent nesting and survival conditions, the 
production trend of ground nesting species, especially blue-wings, and mallards, 
tend to remain about the same under average phenological conditions. During the 
last five years of systematic observation, 1951 marks the only year when a large 
increase of breeding stock occupied the many temporary potholes and nested 
successfully. 
On a few diving ducks, including redheads and ruddies, continue to nest 
each year in Iowa. 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 ducks have been reported during 
the last few years, but like the lesser scaup no evidence of successful nesting has 
been witnessed. A very fewpintails, shovelers, and gadwall nest in the State but 
too few to indicate a trend. 
Special emphasis has been placed upon the study of the wood duck because 
it has again become an important nester during the last fifteen years, and Iowa's 
contribution to the over-all production of this species is important within the flyway. 
This State is reputed to contain from 11,000 to 16,000 miles of stream and rough 
estimates from stream surveys indicated about one pair of wood ducks to every two 
to four miles of good stream habitat in 1953. In 1954 both stream survey data and 
wood duck nesting box checks indicated reduced breeding populations of wood ducks 
within the State (Table I and II)., 
The productive potential of the wood duck in Iowa is not well understood, 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 ten 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 Iowa 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 noteworthy that when the 
waterfowl season has opened in Iowa on October, that the removal of potential 
breeding stock has been reduced roughly one-third in Iowa, (Table III). 
