Brood ecology of mallards and gadwalls nesting on islands in large reservoirs

Article Abstract:

Researchers investigated the survival rate of island-nesting mallard and gadwall ducklings in two large lakes in North Dakota from 1985 to 1987. The objective was to address the concern that large reservoirs may not offer advantageous conditions for duckling survival. The researchers radiotagged a total of 75 nesting females and examined factors affecting wetland use and movement of broods. Duckling survival varied from 0 to 41%. Factors affecting high mortality probably included restrictions in shallow wetland availability near the nesting sites, and movement across large areas of open water.

Patient outcomes, Mortality, Ducks, Mallard, North Dakota, Lake fauna, Lake animals

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Multivariate age assessments of redheads in spring

Article Abstract:

A study has been conducted to evaluate the aging techniques used for waterfowls and to compare the performance of aging birds by using discriminant functions and a posteriori clustering methods. The results revealed that all aging methods may be effective if the appropriate feather variables are used. A posteriori clustering was more effective in measuring large populations than discriminant functions because it avoids errors caused by biased estimators.

Age determination (Zoology), Age determination (Biology)

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Settlement rate of lead shot in tundra wetlands

Article Abstract:

There is little information about the length of time that feeding waterfowl are exposed to spent lead shot left in wetlands. A new study in the Yukon Delta National Wildlife Refuge investigates the length of time that spent lead shot is available to waterfowl in tundra wetlands. The study shows that lead shot settlement is slow and that lead shot is accessible to feeding water fowl more than three years after it is deposited.

Environmental aspects, Alaska, Lead poisoning

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