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Waterfowl and Habitat Changes
After 40 Years on the Waubay Study Area

Table 18

Table 18. Comparisons of brood densities (broods/km²) of ducks (Anatinae) in the Waubay study area, Day County, South Dakota, 1951 vs. 1992, 1953 vs. 1993, and 1950-1953 mean vs. 1992-1993 mean with a 2-sample paired differences t-test.
Years Compared Broods/km²
     1951a vs. 1992
1951 8.57
1992 3.44*
     1953b vs. 1993
1953 9.96
1993 6.29**
     1950-53 vs. 1992-93
1950-53 Mean 9.11
1992-93 Mean 4.86**
a Weather patterns similar to 1992.
b Weather patterns similar to 1993.
* Marginally significant at α = 0.20, df = 12 (shown to minimize the chance of making a Type II error).
** Significant at α = 0.10, df = 12.

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