The knob-billed duck (Sarkidiornis melanotos), male has a very large, black knob on the top of the bill at the base of the forehead. Also known as the African Comb duck, females have a relatively minor bump in the same spot. One of the largest species of duck, it favours wet areas such as swamps, rivers and lakes with scattered trees. Knob-billed Ducks nest mainly in tree holes, also in tall grass.
