Bird of the Month: Ruddy Duck
By Hugh Jennings
PC: Mick Thompson (Ruddy Duck)
Scientific Name: Oxyura jamaicensis
Length 15-16 in
Wingspan 18.5 in
AOU Band code RUDU
The Ruddy Duck (RUDU) is 15-16” long with a wingspan of 18.5”. The genus name Oxyura (OCK-sih-You-rah) is from Greek, oxys meaning sharp-pointed, and oura, tail, referring to the pointed tail of this duck. The species name jamaicensis (jah-may-ih-SEN-sis) is Latin for the island of Jamaica, West Indies, the type of locality from which the first specimen was collected. The RUDU are in the family of stiff-tailed ducks, with spiky tail feathers that are often cocked high in the air. The name Ruddy is for the rust-red breeding plumage of the male.
The Ruddy Duck together with the Cinnamon Teal are the only waterfowl to breed both in N. and S. America. The RUDU is a small, compact duck with a large head and long tail. The adult male in breeding plumage (March to July) is bright ruddy brown, with pure white cheeks, a black cap and nape, and a bright powder-blue bill. In fall and winter, the ruddy brown is replaced by gray, the cap and nape become duller, and the bill gray. The females and immature Ruddy Ducks resemble winter males, except the cheek is a duller off-white, crossed below the eye by a horizontal dark line that can be vague, or missing in some birds.
Their flight is rapid with fast, buzzing wing beats. They are awkward on land and seem reluctant to fly, and have to patter over the water for some distance before gaining flight.
They are widespread breeders in western North America from northern BC and southwest NW Territories east to Manitoba and western Ontario, south to northern Mexico. They winter mainly along both coasts south into Mexico and north to BC, Kansas and New England, and a few to the Great Lakes. It breeds on fresh or alkaline lakes and ponds with extensive marshy borders and areas of open water. In winter it is found on protected shallow bays and estuaries along the coast, and on ice-free lakes and ponds in the interior.
The RUDU forages by diving and swimming underwater, using its bill to strain food items from mud at the bottom of ponds. It feeds on seeds and roots of plants including pondweeds, sedges, smartweeds, coontail, and grasses. It also eats aquatic insects, mollusks, crustaceans, and rarely small fish. Insects and their larvae may be the main foods eaten in summer.
Pairs form after arrival on breeding waters. Male courtship displays including raising the tail over back and bouncing head rapidly so that the bill slaps against the chest.
The nest site is in dense marsh vegetation over shallow water. The nest, built by the female, is a woven platform of grasses, cattails, lined with down, a few inches above water and anchored to standing marsh growth. Sometimes the nest is built on top of an old muskrat house or coot nest. There are 5-10 eggs, typically 8, that are whitish, becoming nest-stained, with rough, granular surface. The eggs are quite large for the size of the bird. Ruddies often lay eggs in each other’s nest and in those of other ducks and marsh birds. The female incubates the eggs for 23-26 days. The young leave the nest within a day after hatching and are able to swim and dive well immediately. The young are tended by the female but feed themselves. The age at first flight is about 6 weeks. RUDUs have one brood per year in the north, and sometimes two in the south.