promising model organism to study and understand the process behind the evolution of flightlessness in birds. Description The Falkland steamer duck measures between 61 and 74 cm in length and has a wingspan of 84 to 94 cm. It is a fairly large species of duck with males weighing between 3300 and 4800 g, and females between 2900 and 4196 g. The male's plumage is brown to grey with a contrasting light grey-white head. They have a very distinctive orange bill. The wings have white secondary feathers and large, featherless spurs. The stubby tail is brown-grey. The eyes are brown with a contrasting white eye-ring and a faint white eye-streak. The females are darker in colour with a brown neck and head, and an olive green beak. Females also have a distinctive white eye ring and a white line behind their eyes. Both males and females have characteristic yellow-orange feet. Juveniles can be differentiated from females by the black marks and overall paler colour of their feet. They also lack or have a very reduced white line behind their eyes. This species is visually similar to another steamer duck species with which it shares its range: the flying steamer duck. Although they are difficult to tell apart in the field, the Falkland steamer duck has shorter wings and tail, and a thicker neck and bill. Finally, as its name implies, the flying steamer duck is capable of flight while the Falkland steamer duck is strictly flightless. This last characteristic is difficult to see in the field because the flying steamer duck seldom flies and is often seen walking or swimming. Historical description Charles Darwin devoted two paragraphs to this bird (or the similar flying steamer duck) in The Voyage of the Beagle, having observed them at the Falkland Islands in 1833: Habitat and Distribution The species' distribution is limited to the Falkland Islands in the South Atlantic Ocean. These ducks are year-round residents of the islands and the surrounding archipelago, and can be found mainly on rugged shores and in sheltered bays. The Falkland steamer ducks also venture inland in freshwater ponds up to 400m from the coast. Behavior This species spends most of its time in small family groups composed of the female, the male and the chicks. However, non-breeding adults and juveniles might gather in larger groups of up to 300. These gatherings can happen at any time