Birds
Lake Duck
Oxyura vittata
A breeding male lake duck pairs a rich chestnut body with a bright sky-blue bill on the surface of a Patagonian lake, while underwater it carries a biological record documented nowhere else among birds.
Overview
The lake duck, Oxyura vittata, is a Least Concern stiff-tailed diving duck found on freshwater lakes and lagoons across Patagonia and adjacent regions. Beyond its striking breeding plumage, the species is widely cited in scientific literature for a single extraordinary trait: males have the longest reproductive organ relative to body size ever documented in a bird.
A duck known for an extreme record
Research into waterfowl reproductive anatomy identified the lake duck as holding an extraordinary record among birds, a finding that has made the species a frequent reference point in scientific discussions of sexual selection in waterfowl.
Status
Least Concern, remaining widespread across suitable freshwater lake and lagoon habitat throughout its southern South American range.
Lake Duck: common questions
Why is the lake duck scientifically notable?
Males have the longest reproductive organ relative to body size documented in any bird, a finding from scientific research into waterfowl mating behaviour that made the species well known among ornithologists.
What does a breeding male lake duck look like?
A breeding male shows a rich chestnut body paired with a bright sky-blue bill, one of the more striking colour combinations among South American ducks.
How does the lake duck swim underwater?
It belongs to the stiff-tailed duck group, using large feet set far back on the body to propel itself underwater while diving for food, with a stiff tail often held upright at the surface.
Where does the lake duck live?
It breeds on freshwater lakes and lagoons across Patagonia and adjacent regions of southern South America, nesting in dense marsh vegetation at the water's edge.