The sheld-duck is a bird of the tidal flats, the saltings, and the sand dunes. It is a large duck and in some of its habits, notably its flight, it resembles a goose rather than a duck. It nests in rabbit burrows in the sand dunes, and sometimes the nest is as much as ten feet from the entrance.
During the breeding season the drake develops a large knob at the base of the bill, but by July this adornment has disappeared. The ducklings are charming in their black and white down.