The flightless species is only known from bones and was presumably driven extinct by visiting sealers and the rats they introduced.

[4] The first bones of this species to be discovered, in 1955–56, were thought to most closely resemble those of a garganey.

[3] In 1987 bones of at least 33 individuals were recovered from rock cavities, revealing a very small duck with a short pointed bill like a wigeon's.

The skull's reduced salt glands indicate it was drinking little seawater, and its bones were recovered from sea level up to 500 m, suggesting it was not living on the coast.

[5] During his visit to Île Saint-Paul (St. Paul Island) on 2 February 1793, explorer John Barrow mentioned the presence of "a small brown duck, not much larger than a thrush" that was "the favourite food of the five sealers living on the island".