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Impact of Red Fox Predation on the Sex Ratio of Prairie Mallards

Table 5: Estimates of Mallard Spring Breeding Populations

Table 5. Estimates of mallard spring breeding populations (in thousands) for the reference area, 1963-73.

Year	Number in strata 45 and 46^a	Number of males in reference area^b
1963	474.8	211.3
1964	376.6	167.6
1965	356.3	158.6
1966	417.1	185.6
1967	412.4	183.5
1968	359.4	159.9
1969	355.9	158.4
1970	636.9	283.4
1971	684.5	304.6
1972	525.6	233.9
1973	449.0	199.8

^a From May waterfowl survey of U.S. Fish and Wildllife Services, adjusted for visibility.
^b Adjusted for size differential between strata 45 and 46 and our reference area.

Previous Section-- Table 4: Various Indices of Red Fox Densities and Estimated Spring Population of Red Fox Families
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Next Section-- Table 6: Incidence of Mallards Found Above Ground at Red Fox Rearing Dens

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