Hi John, no wonder you don´t know what that is...you have a hybrid there : Parents Muscovy duck (Cairina moschata) and Egyptian goose (Alopochen aegyptiacus).The body shape and bill and leg structure are intermediate between both parents, on leg coloration and bill coloration you see the Egyptian goose influence. The coloration is more influenced by (wild-coloured) muscovy duck, thus making this a dark bird...
