Northern Prairie Wildlife Research Center
Factors Associated with Duck Nest Success
in the Prairie Pothole Region of Canada
Geographic and Temporal Effects on Mallard Production
We detected a significant interaction between year and study area for temporary
wetlands and seasonal wetlands among pooled results from areas studied in 1983
and 1984 or 1984 and 1985 (Table 16), indicating that drought did not affect each
study area similarly in all years. Temporary wetlands were highly variable (both
geographically and annually), seasonal wetlands were less variable than temporary
ones, and semipermanent wetlands were even less variable. Temporary wetlands were
about equally variable from year to year as among areas, as indicated by the ratios
of their CV's (CVY/CVSA = 0.91). Seasonal wetlands were
more variable year to year than among areas (CVY/CVSA =
1.49). As expected from their greater permanence, semipermanent wetlands varied
less from year to year than among areas (CVY/CVSA = 0.49).
Pairs were moderately variable, and equally so among years and areas (CVY/CVSA
= 0.95). Nest success also was moderately variable, but somewhat more so among
years than areas (CVY/CVSA = 1.69).
Table 16. Statistics associated with variance components of factors
involved in mallard production: mean, variance components, and coefficients
of variation (CV = square root of variance component divided by mean).
| Dependent variable
|| Variance component
|| CV (%)
|| Study area
|| Study area times year
|| Study area
|Nest success rate
to those that contained visible standing water in May.
component not significantly different from zero.
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