Reproductive performance of Common Goldeneye Bucephala clangula females in relation to age and lifespan

We studied the effects of female age and length of lifespan on reproductive performance in the Common Goldeneye Bucephala clangula , a precocial species with self-feeding chicks. Dependent variables studied were the occurrence of failed nesting attempts and non-breeding years, clutch size, nesting and hatching success, female condition and recovery rate of offspring. To avoid misinterpretations resulting from age-dependent quality changes in the cohorts, individuals with different lifespans were separated in the analyses. There was no evidence that females of different lifespan differed in reproductive strategy. The data revealed no significant differences in nest losses, occurrence of non-breeding years, timing of nesting or clutch size, but the physiological condition of short-lived females was poorer than that of longer living females. This accords with the prediction that poor-quality females invest proportionally more in reproduction than high-quality females and consequently die earlier. The most productive individuals were those that lived longest. The only indication of senescence was the low recovery rate of offspring produced by old females. The last breeding attempt did not differ in any observable respect from the penultimate attempt, implying that the last investment in reproduction was no heavier than the previous one.