Length: 61 – 63 cm
Wingspan: 110 – 133 cm
Weight: 850 – 1500 g
Adult male shelducks in breeding plumage have a white body with a broad chestnut band from the upper mantle to the lower breast. On the upperwing the tertials have brown edges, the secondaries are glossy green, and the primaries are black. The tail is white with a black terminal band.
The underparts are white with a black band from the lower breast to the vent. The undertail coverts are chestnut, the underwing coverts are white, and the flight feathers are black.
Shelducks have a black head with a dark green gloss. The bill is bright red with a conspicuous knob at the base, the eyes are dark brown and the legs and webbed feet are pale pink.
Female shelducks are similar to males except they are duller overall and have a narrower breast band. The bill is duller with white spots around the base and no knob.
Out of breeding plumage shelducks are duller and greyer with black and white markings on the breast band and white spots on the face. The white body feathers have narrow brown edges and in the male the size of the knob is reduced.
Juveniles are duller still and have no breast band. The face and foreneck are white and it lacks the green secondary feathers. The bill, legs and feet are pale slate-grey.
Shelducks are monogamous and mate for life. They begin breeding between April and June. The female chooses the nest site in a cavity in caves, hollow trees, or abandoned rabbit burrows. The nest is made from grass and moss and lined with down.
Shelducks lay 7-12 creamy white eggs which are incubated by the female alone for 29-31 days. The male remains close by the nest. Chicks leave the nest soon after hatching and fledge about 45-50 days later when they become independent. Females reach sexual maturity at 2 years, and males at 4-5 years.
They are sociable birds and will live in large colonies leaving their young chicks in crèches with just one or two adults.
Shelducks mainly eat small aquatic invertebrates including insects, molluscs and crustaceans, as well as small fish, worms, and plant matter.
They forage in shallow water by upending and head-dipping, and by digging and dabbling on mud flats.
Where to see them
Shelducks are common around the coastline although they can also be found in inland waters, such as reservoirs, and gravel pits.
They can be seen at any time of year with the population growing to more than 81,000 during the winter.
Louis A. Hansen/xeno-canto
Did you know?
Young shelducks will dive under water to avoid predators while the adults will fly away from them to act as a decoy.