Article Abstract:
Many studies of birds show that maintenance of parental body weight is important to successfully raise offspring without compromising parent survival. A new study of European diving ducks tests one component of the nutrient limitation theory to discover whether heavier females are more successful in raising broods than lighter females. The study of the common pochard and the tufted duck on Engmure Marsh, Latvia, shows little differences in the body masses of females of successful, abandoned and depredated nests. Survival rates in both species are unrelated to adult female body mass. The study supports the theory that levels of nutrient reserves may be important predictors of nesting success.
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Article Abstract:
An examination of the relationship between competitive foraging abilities and age-specific mortality in Rock Doves indicates that differences in competitive abilities over food may partly explain the differential mortality of juvenile and adult pigeons. In all situations analyzed, young pigeons were poorer competitors compared with adults. They foraged more slowly which made them more vulnerable to exploitation competition and their subordination to adults within their social system rendered them disadvantaged.
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Article Abstract:
Capture-recapture and band recovery models were used to evaluate survival and breeding probabilities for female ground-nesting and over-water nesting European ducks in a specific Latvian study area. Model survival estimates and band recovery locations were compared to test for female philopatry. Estimates for the pochard were shown to be age-specific. Tufted ducks, common pochards and northern shovelers were ranked accordingly based on annual survival probabilities.
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