Biology

During the non-breeding season, when flocks of Steller's eider inhabit salt water, remarkable synchronised foraging can be observed, with large flocks diving and resurfacing in unison as they feed on marine worms, clams, mussels, snails, limpets, shrimp and crabs (2) (6) (9). During the breeding season when Steller's eider inhabits tundra wetlands, it is thought to feed on insect larvae, seeds, shrimps and flies (2). Shortly before departure from the wintering range, Steller's eiders pair up, migrating together to their breeding habitat (6) (9). Upon arrival, the female selects a nest site, hollowing out a bowl and lining it with grasses, lichens and down (6). Steller's eiders lay clutches of around five eggs, which are incubated for 24 days (10). Steller's eiders do not nest every year, but interestingly, it has been observed that they tend to nest in years when there is a abundance of lemmings, nesting pomarine jaegers (Stercorarius pomarinus) and snowy owls (Bubo scandiacus). This is thought to be for two reasons; an abundance of lemmings may provide an alternative prey source for foxes and other predators of eiders; while jaegers and owls may unintentionally provide protection to nearby nesting eiders whilst protecting their own nests (10).