Lead concentrations in blood from incubating common eiders (Somateria mollissima) in the Baltic Sea

Here we investigate if lead may be a contributing factor to the observed population decline in a Baltic colony of incubating eiders (Somateria mollissima). Body mass and blood samples were obtained from 50 incubating female eiders at the Baltic breeding colony on Christiansø during spring 2017 (n = 27) and 2018 (n = 23). All the females were sampled twice during early (day 4) and late (day 24) incubation. The full blood was analysed for lead to investigate if the concentrations exceeded toxic thresholds or changed over the incubation period due to remobilisation from bones and liver tissue. Body mass, hatch date and number of chicks were also analysed with respect to lead concentrations. The body mass (mean ± SD g) increased significantly in the order: day 24 in 2018 (1561 ± 154 g) Peer reviewe

Incubation Behaviour of Common Eiders Somateria Mollissima in the Central Baltic: Nest Attendance and Loss in Body Mass

Here we present the recording of body mass change and weight loss during incubation in a Common Eider Somateria mollissima colony at Christiansø in the Central Baltic (55°19'N 15°11'E). The study was conducted during April and May 2015 and a total number of four birds were followed (two were lost due to predation and three due to power outages). Body mass and nesting behaviour was recorded electronically over a period of 26-27 days using automatic poultry scales and a surveillance video camera. During incubation, the eiders underwent a 28-37% loss in body mass and left the nest on average 13 times (range: 7-17 times) for a period of 7-70 min. In general, birds with high initial body mass left their nest for a shorter total time than birds with lower initial body mass. The recorded daily changes in body mass indicate that the eiders foraged during the incubation period, not just leaving the nest for rehydration or in response to disturbance, which improve our current understanding of eider incubation behaviour. Such information is important to fully understanding of eider breeding biology in order to better conserve and manage the species during its breeding seasons where individual birds undergo extreme stress that may affect reproductive outcome and adult survival