The Pink-eared Duck (Malacorhynchus membranaceus) is a species of duck found in Australia. It is the only living member of the genus Malacorhynchus; a closely related, but slightly larger extinct form from New Zealand was described as Scarlett’s Duck (Malacorhynchus scarletti).
It has a large spatulate bill like that of the Australasian Shoveler, but is smaller at 38-40 cm in length. Its brown back and crown, black and white barred sides and black eye patches on its otherwise white face make this bird unmistakable. Juveniles are somewhat duller than adult birds but are otherwise similar.
They are widely distributed throughout Australia and these highly mobile ducks can be found anywhere there is productive water, especially in dry inland regions, where annual rainfall rarely exceeds 15 inches.
These small ducks are unmistakable, with an enormous square-tipped bill and a bold black and white stripe pattern on their lower parts, making the seldom-used Australian name of Zebra Duck more appropriate. Their tiny, bright rose-colored ear-patches (slightly above and behind the eye) are scarcely visible except at close range.
Their diet consists of plankton, as well as crustaceans, mollusks and insects. Their bill is well designed for straining minute organisms, with pliable mandibular flaps that channel water in a manner that allow the ducks to filter algae and plankton efficiently. They also feed by vortexing, in which two ducks spin about a central point with the head of one opposite the tail of the other, concentrating food in a gyrating water column.
Breeding and nesting are stimulated by the drying and filling of pools that promote increased levels of organic material. In good years, large numbers of Pink-eared ducks concentrate in shallow flood plains. However, when conditions do not meet specifications, reproduction may be completely curtailed.