Polysticta stelleri

A medium-sized sea duck. The male has a white head, black occipital, eye area, throat, back of neck and tail. The rest of the lower body is creamy yellow with a black spot on the chest. Similar species such as the white merganser have black eye patches, and the long-tailed duck has dark cheeks. The female is dark brown with a lighter eye area. It is distinguished from other brown sea ducks and diving ducks by its green wing mirror. The iris is brown, the bill is gray-black, and the feet are dark brown.

It rarely overwinter in Northeast and North China. It breeds in the Arctic regions of Siberia and Alaska abroad and overwinter in Northern Europe, northern East Asia and northwestern North America.

It inhabits freshwater swamps, ponds, and shallow coastal and estuary waters, often moving in groups.

Little eider ducks like to live in groups. Except for the period of nesting and laying eggs, they live in groups almost all year round, especially during molting, migration and wintering, often in large groups of thousands or even tens of thousands. They fly fast and lightly, flap their wings quickly, and take off from the water flexibly and lightly. They can fly directly from the water without flapping on the water surface. They swim fast and lightly, and their tails are often raised when swimming. They are also good at diving.

Migration is carried out along the coast. In spring, they usually arrive at the breeding grounds at the end of May. In autumn, some leave the breeding grounds as early as mid-to-late August, but a large number of them begin to migrate away from the breeding grounds in late August and early September. They usually migrate in large groups.

The eider duck mainly feeds on aquatic insects and larvae, mollusks, crustaceans, small fish and other animal foods, and also eats a small amount of plant food. They forage mostly in shallow waters near the coast and in lakes and ponds in the Arctic tundra. They mainly feed by diving.

When showing off, the male bird makes low croons-like calls and short barks. The female bird makes low barks, howls and whistles. It is quite quiet at other times.

The breeding season is from June to August. Usually it arrives at the breeding grounds in late May or early June. It nests on the Arctic tundra, and the nests are mostly placed in the grass and low bushes on the ground beside rivers and ponds. The nest is extremely simple, made of some dead grass and moss collected on the spot. A large amount of black-brown down feathers are placed inside. Each nest contains 6-7 eggs, occasionally up to 10. The female incubates the eggs. The eggs are light yellow or orange-brown. They are smooth and spotless, measuring 55-71×37-47 mm, averaging 61×42 mm, and weighing 58 grams.