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The
American Black Duck (Anas rubripes) is a medium-sized
dabbling duck. The adult male has a yellow bill, a dark
body, lighter head and neck, orange legs and dark eyes.
The adult female has a similar appearance. Both sexes
have a shiny purple-blue wing patch, which is not bordered
with white as with the Mallard. Their breeding habitat
is lakes, ponds, rivers, marshes and other aquatic environments
in eastern Canada including the Great Lakes. Black ducks
interbreed regularly and extensively with Mallard ducks,
to which they are closely related; some authorities consider
that Black Duck is no more than a dark-plumaged race of
Mallard, not a separate species at all. The behaviour
and voice are the same as for Mallard. In the past, Black
Ducks and Mallards were separated by habitat, with the
dark-plumaged Black Ducks having a selective advantage
in shaded forest pools in eastern North America, and the
lighter plumaged Mallards in the brighter, more open prairie
and plains lakes. |
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In
recent times, deforestation in the east, and tree planting
on the plains, has broken down this habitat separation,
leading to the high levels of hybridisation now seen.
They are partially migratory and many winter in the east-central
United States, especially coastal areas; some remain year-round
in the Great Lakes region. This duck is a rare vagrant
to Great Britain, where, over the years, several birds
have settled in and bred with the local Mallards. The
resulting hybrids can present considerable identification
difficulties. The eggs are a greenish buff color. They
lay from 6-14 eggs, and hatch in an average of 30 days.
These birds feed by dabbling in shallow water, and grazing
on land. They mainly eat plants, but also some molluscs
and aquatic insects. |
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