The spot-backed diving duck (scientific name: Aythya marila) is 42–47 cm long, has a wingspan of 68–75 cm, and weighs 750–1350 g, making it a medium-sized dwarf duck. The male is longer than the crested diving duck, with a gray back and no crown. The female differs from the female crested diving duck in that it has a wide white ring at the base of its beak.
South of the Yangtze River, Southeast China coasts Guangdong, Guangxi and Taiwan. During the migration, it passed through Jilin, Liaoning, Hebei, Shandong and other provinces.
The spot-backed diving duck is a migratory bird that migrates to China in early October in the fall and leaves in early April to early May in the spring. During the breeding period, they are in pairs, and during the non-breeding period, they prefer to flock. Sometimes they also mix with other ducks. Good at swimming and diving. Taking off requires two wings to beat the water rapidly, and it takes a while to run on the water to fly, the action seems clumsy, but the flight is fast and powerful.
The breeding season is from May to July. Pairs are usually formed at the end of winter, often reaching breeding grounds in groups of pairs. Nests are located on dry ground outside lakes or rivers, usually close to the water's edge, and nests are mostly placed on the ground next to dry grass or fresh grass, or under small willow trees and shrubs, and the nests are better hidden. It is usually made of dry grass with down feathers inside. 7-10 eggs are laid per clutch