It inhabits the rocky coasts and coastal islands from southern Chile and Chiloé to Tierra del Fuego, switching to the adjacent sheltered bays and lakes further inland when breeding.

It is a massively built waterfowl at 3.5–7 kg (7.7–15.4 lb) and 65–84 cm (26–33 in) in length, with the males noticeably larger than the females.

Adult males are known to be extremely aggressive during mating season, including towards other waterfowl, but may join mixed-species winter flocks without incident.

There are several potential predators of eggs and young birds: foxes, caracaras, gulls, skuas and giant petrels.

During the breeding season, they tend to eat and feed their young small snails, insect larvae, amphipods and isopods.

Incidents have allegedly occurred where a raging male was placed by a misguided collector among adults of various other waterfowl species and killed all the other birds with its powerful, spurred wings.