About Anas superciliosa J.F.Gmelin, 1789
This is a description of Anas superciliosa J.F.Gmelin, 1789, a sociable duck species. It lives in a wide variety of wetland habitats, and its nesting habits are very similar to those of the mallard, which is encroaching on its range in New Zealand. Like other Anas ducks, it feeds by upending. It has a dark body, a paler head with a dark crown and facial stripes. When in flight, it shows a green speculum and pale underwing. All of its plumages are similar. Its total length ranges from 54–61 cm (21–24 in); males tend to be larger than females, and some island forms are smaller and darker than the main populations. This species is not resident on the Marianas islands, but it sometimes occurs there during migration. The now-extinct Mariana mallard was probably originally derived from hybrids between this species and the mallard, which came to the islands during migration and settled there. Like its relatives the mallard and American black duck, the Pacific black duck is one of a number of duck species that can quack. The female produces a sequence of raucous, rapid quacking that decreases in volume.
