Oxyura jamaicensis

In addition to the breeding period, the brown-tailed ducks are mostly active in small groups. Good at swimming and diving. It is found in waters close to aquatic plants. Tail up when swimming. It can either float lightly in the water or sink its body, leaving only its head and tail in the water, especially when in danger. Generally do not go on land activities, and rarely fly, even if there is danger, often by diving or swimming, hiding to escape. It was difficult to walk on the ground and awkward to take off, requiring a quick flap of the wings on the water to fly. In addition to the breeding period, there is generally little singing, and the activity is silent.

Brown hardtail ducks feed mainly by diving, but also directly at the water's edge in shallow water. It feeds on aquatic plants, insects, insect larvae, small fish, frogs, crustaceans, mollusks, worms and other aquatic animals.

The breeding season is from May to July. The nest is a floating nest built in shrubs or grass on the ground near water. Each clutch lays 6-10 eggs. Incubation period is 25 days.

The brown hardtail duck is one of the most dangerous invaders in the UK. They have interbred with the British white-headed hardtail, putting this rare duck "lineage" under serious threat. Originally distributed in North America, the brown hardtail duck was introduced to the United Kingdom in the early 20th century and escaped into the wild to form a natural population and rapidly expanded. By the 1970s, the range of the brown hardtail had expanded to most of continental Europe. The brown hardtail duck can cross with its local relative, Oxyura leucocephala, and overlap with the white-headed hardtail duck in the selection of breeding areas and nesting sites, resulting in the loss of the unique genes of the globally endangered white-headed hardtail and the threat of extinction (Perennou, 1997). As of 2007, the population of the white-headed hardtail in Western Europe is only about 1,000 individuals, and breeds only in Spain, where there is no distribution of the brown hardtail (BirdLife Interna-tional, 2000).