The Spotted Duck is a migratory bird. It begins to migrate to China for wintering in early October every autumn and leaves in early April to early May in spring. It moves in pairs during the breeding season and in groups during the non-breeding season. Sometimes it also moves in mixed groups with other diving ducks. It is good at swimming and diving. When taking off, it needs to flap its wings rapidly on the water surface and run on the water for a while before it can fly. The movements appear clumsy, but the flight is fast and powerful.
It mainly feeds on aquatic animals such as crustaceans, mollusks, aquatic insects, small fish, etc. It also eats algae, aquatic plant leaves, stems, seeds, etc. It mainly forages by diving. The diving depth is usually 2-3 meters. It usually forages during the day. When resting, it often wanders in groups on the sea or lake, or floats motionlessly on the water and drifts with the waves.
The breeding season is from May to July. Usually they form pairs in late winter and often arrive at the breeding ground in pairs. They build nests on dry land outside lakes or rivers, usually close to the water. The nests are mostly placed on the ground next to dead grass or fresh grass, or under small willows and shrubs. The nests are well hidden. They are usually made of dead grass and padded with down feathers. Each nest lays 7-10 eggs. Usually one egg per day. The eggs are gray-olive or brown, with a size of 54.5-68.1×40.7-48 mm; an average of 62.7×71.5 mm, and weigh 57-72.5 grams, with an average of 60.7 grams. Incubation begins just after the first egg is laid. The female bird is responsible for incubation. The incubation period is 27-28 days. The male bird leaves the female bird after the female bird starts incubating the eggs and gathers with other flocks of birds at the waterside to molt. The chicks are female and will follow their parents soon after hatching. After about 40-50 days of chick life under the guidance of their parents, they will be able to fly.