Dispersal, movements and site fidelity of post‐fledging King Eiders Somateria spectabilis and their attendant females

Post‐fledging dispersal and site fidelity are poorly understood, particularly for sea ducks that spend the majority of their annual cycle at sea. This is the first description of movements and their timing for first‐year (juvenile) and second‐year (subadult) King Eiders Somateria spectabilis in relation to their attendant females. We fitted satellite transmitters that operated for 2 years to 63 hatch‐year birds and 17 attendant females at breeding areas in northern Alaska in 2006–2009. Our goals were to describe the spatio‐temporal distribution of pre‐breeding individuals and adult females that had been successful breeders. We also examined fidelity to wing moulting and wintering areas as well as natal philopatry. Juveniles did not appear to follow attendant adults, although they did winter in the same three general wintering areas, suggesting that genetic inheritance and social factors may have roles in the initial migration from the breeding area. Additionally, juveniles were more variable in the timing and duration of migration, moved longer distances during the winter, and were less faithful to moulting and wintering areas than adults, indicating that individual exploration and acquired navigational memory played a role in subsequent migrations. Most (75%) subadult females returned to natal areas, probably prospecting for future nesting sites, whereas subadult males were widely dispersed at sea. Timing and duration of moult migration and wing moult of adult females that were presumed to be successful breeders differed from those of unsuccessful breeders due to the extended time that the former spent on the breeding grounds. Temporal and spatial segregation of post‐fledging King Eiders from adults has direct management implications in terms of resource development and population dynamics.