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The American blue duck (Psudeohymenolaimus opalus) is a species of duck that originally did not exist, but has since been created by SciiFii and introduced throughout the rainforests, wetlands, forests, open woodlands, lakes, rivers, and ponds across North America to help boost biodiversity. Despite its name, appearance, or calls, the American blue duck is not related to the New Zealand blue duck (Hymenolaimus malacorhynchos), but is most closely related to the mallard duck (Anas platyrhynchos). The American blue duck is 53 to 54 cm (21–21 in) long and varies in weight by sex. Females are smaller than males, weighing 680–870 g (24–31 oz), whereas the males weigh 820–1,077 g (28.9–38.0 oz). The plumage is a dark slate-grey with a greenish sheen on the head, a chestnut-flecked breast. The outer secondaries are tipped with white and the inner ones have black margins. The plumage of the two sexes are mostly the same, although the female has slightly less chestnut in the chest. The pinkish-white bill has fleshy flaps of skin hanging from the sides of its tip. The blue duck hatches with a green beak for just 8 hours after hatching; after which it then develops its final colour. The male's call is a high-pitched whistle. The female's call is a rattling growl or low-pitched grating notes. The American blue duck feeds almost entirely on aquatic invertebrates, with the majority of food items being made up of caddisfly larvae. It may on occasion take berries and the fruits of shrubs. The American blue duck can nest in hollow logs, small caves, burrows, and other sheltered spots. It is a powerful swimmer even in strong currents, but is reluctant to fly. American blue ducks nest between April and June, laying 4–9 creamy white eggs. The female incubates the eggs for 35 days and chicks can fly when about 70 days old. Nesting and egg incubation of seven to thirteen eggs is undertaken by the female while the male stands guard. Nests are shallow, twig, grass and down-lined scrapes in caves, burrows, under river-side vegetation or in log-jams. Their breeding success is extremely variable from one year to the next. The conservation status of the American blue duck is Least Concern due to successful conservation efforts, the American blue duck's wide range and its tolerance to many of the human activities.