Factors affecting clutch Size and Duckling Survival in the Common Goldeneye Bucephala clangula

Abstract

Female age and condition as well as nesting schedule may affect clutch size and chick survival, which both are important factors affecting the annual reproductive output. Clutch size and chick survival are often interrelated in altricial birds but in precocial species the interrelation is dubious. To study factors affecting clutch size and the survival of ducklings in the common goldeneye Bucephala clangula, we examined ringing‐recovery data, supplied by ringers, from seven intensively studied goldeneye populations from different parts of Finland. Due to large sample sizes it was possible to distinquish the effects of interrelated variables, e.g. female age and hatching date. Clutch size was significantly associated with both female age and hatching date; first‐time breeders and late breeders had small clutches. Clutch size was not associated with female condition. The recovery rate of ducklings was associated with hatching date (low in late broods) but not with female age, condition or brood size. The natal brood sizes of recruited female ducklings did not differ from annual averages, but the natal hatching date of recruited females was earlier and their mothers were older than annual averages in the populations into which the recruited females were bom. The timing of nesting was the most important factor affecting the reproductive output of common goldeneye females in a given year.

Spring phenology and timing of breeding in short‐distance migrant birds: phenotypic responses and offspring recruitment patterns in common goldeneyes

“…That only ∼ 21% of females produced virtually all recruits is consistent with patterns reported for other vertebrates (Clutton‐Brock , Newton ) including several duck species (Blums and Clark ). Previous analyses of factors affecting recruitment processes in this goldeneye population had much smaller sample size of recruits (n = 31) and used statistical techniques (pair‐wise comparisons in terms of brood size, timing of nesting and female age; for details see Milonoff et al ) that could not distinguish direct and indirect effects of explanatory variables. Therefore, even though hatching date and female age both affected recruitment rate, it was not possible to assess the relative contribution of age per se to reproductive success (Milonoff et al ).…”

“…Previous analyses of factors affecting recruitment processes in this goldeneye population had much smaller sample size of recruits (n = 31) and used statistical techniques (pair‐wise comparisons in terms of brood size, timing of nesting and female age; for details see Milonoff et al ) that could not distinguish direct and indirect effects of explanatory variables. Therefore, even though hatching date and female age both affected recruitment rate, it was not possible to assess the relative contribution of age per se to reproductive success (Milonoff et al ). The path analysis results presented here were based on four times more data and revealed that female age did not directly affect offspring recruitment; rather, an age effect is mediated via indirect effects on timing of breeding, body condition and brood size.…”

Do parasitic common goldeneyeBucephala clangulafemales choose nests on the basis of host traits or nest site traits?

“…In addition to the nest site characteristics, the occurrence of CBP was also associated with nesting schedule: early broods were more frequently parasitized than late broods. Early goldeneye broods have a higher chick survival rate and produce more recruits (Dow and Fredga 1984, Milonoff et al 1998). Furthermore, early breeding attempts often are in nest sites that have low predation risk (Pöysä 1999b).…”

“…females not born in the study area but captured as adults the first time), we used the number of nesting years (i.e. the number of years from the first recorded nesting attempt for a given female before current nesting attempt) as the measure of female experience (see also Dow and Fredga 1984, Milonoff et al 1998, 2002). As an index of female condition, we used the residuals from the body mass on wing length regression based on pooled data (e.g.…”

“…Natal philopatry is high among goldeneye females and old females are philopatric to their nest site (Dow and Fredga 1983, Pöysä et al 1997), making it possible to study the occurrence of CBP both within a given female and in a given nest site over several years. In general, early breeding and more experienced females in a good physiological condition are the most productive ones in the goldeneye (Dow and Fredga 1984, Milonoff et al 1998, 2002) and many other duck species (e.g. Hepp and Kennamer 1993, Blums et al 2002a, Blums and Clark 2004).…”