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

Abstract

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.

Life history patterns, individual heterogeneity, and density dependence in breeding common goldeneyes of the northern boreal forest

“…Our results suggest that substantial heterogeneity in individual quality exists in goldeneyes breeding in Alaska, as indicated by extensive support for individual covariate effects in juvenile demographic parameters (φ J and ψ PB ), and the positive covariation among demographic components observed in adults (Cam et al ). The latter finding is consistent with other goldeneye studies (Dow and Fredga , Milonoff et al ). Prior nest success (NS) was positively associated with adult female detection, and breeding and survival probabilities, though the confidence intervals overlapped zero slightly in the latter two parameters.…”

“…Both lower nest success and increased use of parasitic egg‐laying would reduce detection probability of two‐year‐olds relative to older females. Age‐related variation in detection probability may account for the discrepancy between the high probability of recruitment at two years of age we found, and other goldeneye studies that reported average age of first breeding closer to three‐years‐old (Eadie et al , Milonoff et al ). These latter studies based their estimates of age at first breeding solely on observations of observed‐first time breeding attempts, which are likely to be biased high due to the lower detection probability of two‐year‐olds.…”

“…Goldeneye females return to their natal grounds as yearlings to prospect for potential nest sites to use the following year (Eadie and Gauthier ). Limited nest site availability during prospecting may potentially deter female recruitment the following year, as inexperienced females typically initiate nesting later than experienced females (Dow and Fredga , Milonoff et al ) and are therefore less likely to secure a suitable nest site. Similarly, Boyd et al () detected a negative correlation between first‐year apparent survival rates and subsequent within‐cohort apparent survival in Barrow's goldeneyes.…”

“…Multiple goldeneye studies have reported positive covariance among demographic traits (Dow and Fredga , Milonoff et al ), meaning that the longest lived females were the most productive (i.e. of higher quality).…”

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

“…Hepp and Kennamer 1993;Milonoff et al 2002;Blums et al 2005). Winter body condition is, however, also a parameter of great importance, likely to affect duck survival during that season specifically (e.g.…”