Factors Associated with Duck Nest Success
in the Prairie Pothole Region of Canada
Nesting Chronology
We estimated the date each nest was initiated by counting back from the date it was found, 1 day for each egg in the clutch and one day for each day of incubation minus 1. We calculated median date of nest initiation and interquartile range of initiation dates for each of the 5 common species in each area-year. For each of the 5 common species, we performed multiple regression analyses relating (1) median date of nest initiation and (2) interquartile range of initiation dates to nest success, percentage of seasonal wetlands that were wet in May, and average temperature and total precipitation each month, April through June. We used the interquartile range (the difference between third and first quartiles) as a measure of the central span of the nesting period. The median date of nest initiation and interquartile range of initiation dates were compared among the 5 common species with analysis of variance. When an overall difference was detected, linear contrasts were used to identify which species were different. Each area-year for which we had >=10 nests was assigned a weight equal to the square root of the number of nests. Area-years with <10 nests were not used because we considered them inadequate for estimating these nesting parameters.
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