Identifier

etd-04262010-165549

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Mallards Anas platyrhnchos are arguably the most researched waterfowl species in North America. They exhibit great flexibility in certain breeding metrics such as timing of nest initiation and clutch size. A study on captive female Mallards (Batt and Prince 1979) fed ad libitum, held in identical breeding compartments, and paired with the same mate in each year of the study exhibited substantial variation in the timing of nest initiation within a given year, yet some individual females demonstrated consistency in initiation date among years. My objective was to examine breeding metrics such as timing of nest initiation and clutch size and to evaluate age-related productivity in conjunction with those metrics. More specifically, I wanted to know if individual females were consistent in first initiated nests among years. Secondly, I wanted to know if age affected both the timing of nest initiation and clutch size. From 2006-2009 nest searching crews found 2274 Mallard nests and captured 944 females using various trapping techniques. I found strong evidence for variation among birds within year. I failed to find a significant influence of individual variation among birds between years. Age was not significant in impacting when an individual nests. The effects of nest year were also tested but were not significant. For my clutch size analysis, all 944 females captured were used and categorized to an age group based on wing feather characteristics. Age, year, and julian date all had significant impacts on clutch size. After second year (ASY) females had 0.32 more eggs than second year (SY) females. Clutch size varied by year and declined seasonally, such that for every day of delay clutch size was reduced by 0.05 eggs. Mallards exhibit great flexibility in the timing of nest initiation for which they breed. However, approximately 36% of the females show consistency in their individual nesting dates which were prior to the mean annual initiation date. Some individuals consistently nested later than the mean annual initiation date. Nevertheless, there appears to be strong directional selection for early nesting.

Date

2010

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Rohwer, Frank C

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