Survival of spectacled eider adult females and ducklings during brood rearing

We studied survival of adult female and duckling spectacled eiders (Somateria fischeri) during brood rearing on the Yukon-Kuskokwim Delta, Alaska from 1993 to 1995. Duckling survival to 30 days of age averaged 34% with a 95% confidence interval from 25 to 47%. Half (49%) of radiomarked adult females had lost all their ducklings by 30 days after hatch. Most (74%) duckling mortality occurred in the first 10 days. Adult female survival during the first 30 days of brood rearing was 93 ± 3% (SE). Females died from lead poisoning, as a result of ingesting lead shot, and predation. Mortality of adult females during brood rearing is probably higher than during other times of the year. Low adult female survival during the breeding season may be contributing to the overall population decline of spectacled eiders.