The diet of the Falkland steamerduck consists mainly of marine molluscs, such as mussels, limpets and sea snails, and crustaceans such as crabs and shrimps (2) (3) (4) (5) (6). The shells of its prey are crushed in the powerful beak (5). The Falkland steamerduck upends to feed in shallow water, or dives, using the wings and feet to propel itself underwater (2) (4) (5) (6). It may also search for food along the water’s edge, and its feeding activity is strongly associated with the tides (4).
Although the Falkland steamerduck may nest at any time of year, most breeding takes places between September and December. The nest is built close to water, usually amongst vegetation or in an abandoned penguin burrow (2) (4) (5) (6). It consists of a shallow depression, lined with feathers and sometimes strengthened with sticks or grass (4) (6). The female alone incubates the clutch of 4 to 11 eggs, which hatch after around 34 days (2) (4), but the male helps care for the chicks and defends them aggressively (5). Young Falkland steamerducks fledge after about 12 weeks (2) (4), and females have been recorded breeding for the first time in their second year (4). In captivity, this species has lived for up to 20 years (4).
The Falkland steamerduck is a highly aggressive and territorial species, and pairs defend a section of coastline year-round, not only against other steamerducks but also against any intruding bird species (4) (6) (8). Territorial disputes can be bloody, the combatants using well-developed spurs on the wings to fight, and injuries are common (6) (8). Immature and non-breeding individuals often congregate in large flocks away from established territories (3) (4) (6).
This species’ chicks are vulnerable to predators such as gulls and skuas, but adult Falkland steamerducks have no natural enemies apart from sea lions (2) (4) (6). As it is flightless, the Falkland steamerduck can only escape by diving or by ‘steaming’ (3), but the short wings are surprisingly powerful and, together with its large feet, are well suited to moving this heavy duck over the water (5) (9).