American Black Duck Anas rubripes
The American black duck are a simular size to the mallard and measure between 48-63cm in length and wing span between 88-96cm across.The colouration of the American black duck resembles a femaale mallard, although the Black Duck's plumage is darker. The male and female Black Duck are generally similar in appearance, but the male's bill is yellow while the female's is a dull green. The head is slightly lighter brown than the dark brown body, and the speculum are iridescent violet-blue with predominantly black margins. The Black Duck has orange legs and dark eyes. In flight, the white underwings can be seen in contrast to the dark brown body. The behaviour and voice are the same as for the Mallard drake.
The American Black Duck can lay upto 9 eggs in a single clutch and have been known interbreed with mallards. They get mistaken for being a subspecies of the mallard but when they interbreed with the mallard the chicks often fail to survive which can have an impact on the population of the species.
In the United Kingdom the American Black Duck are a rare vagrant since they are native to America. They are also kown to breed in in the U,K but only small numbers do and often with the local Mallards. The resulting hybrids can present considerable identification difficulties.