A partial migrant over much of Europe, the shelduck (Tadorna tadorna) is found mainly on muddy coasts and estuaries, but when breeding can also be seen on heathland and farmland close to the sea. After breeding, most shelducks migrate to traditional moulting areas, of which the most popular is the Heligoland Bight off the north German coast.
Gooselike in general appearance, the shelduck measures up to 610 mm (24 inches) in length. The body is white apart from a broad chestnut band across the breast and a dark streak down the centre of the belly. The head and neck are dark green. The wing feathers are black and white, and there are noticeable green specula (secondary feathers). The legs are flesh coloured and the bill red.
Male shelducks are larger and more brightly coloured than the females, and have a pronounced knob at the base of the bill.
Shelducks are normally silent, but during the breeding season produce “ak-ak-ak” and “ark-ark” calls.
They feed on shellfish, crabs, shrimps, sandhoppers, worms and insect larvae. Their feeding method is either to up-end from the water surface or to wade through mud and sweep the bill from side to side.
Shelducks nest in dense vegetation, often in abandoned rabbit holes. The nest comprises straw and grass lined with down from the female bird. Eight to ten eggs are laid in April or May, with incubation (by the female) taking about 30 days. The young birds are able to feed themselves almost as soon as they hatch and they can fly after 45 days.