Lakes, Rivers, and Swamps
Here the area of habitat has been greatly reduced by swamp draining. Of the native ducks, the brown duck (Anas chlorotis) and New Zealand scaup (or black teal) (Aythya novaeseelandiae) were the most affected by the coming of settlement and, even with full protection, are only slowly recovering; the brown duck especially is now a rare species. The widely distributed native grey duck (Anas superciliosa) has to meet in some districts the increasing competition of the introduced mallard (Anas platyrhynchos); an associated species on most inland waters is the handsome shoveler (Anas rhynchotis), while the grey teal (Anas gibberfrons) is at present expanding. Two larger species, both introduced, are well established: the Canada goose (Branta canadensis) breeding in the South Island, and a straggler to the North Island, and the abundant black swan (Cygnus atratus).
The most striking of the waterfowl, the paradise duck (Tadorna variegata), is now an inhabitant of upland river valleys and lakes, but originally occurred on all inland waters: metallic blacks and browns characterise the male, while the female has a chestnut brown body and conspicuous white head. Another species of note is the blue duck (Hymenolaimus malacorhynchus), adapted to feed in the swifter streams and mountain torrents.
Swamp and lake-edge birds include the rare white heron (Egretta alba), white-faced heron (Notophoyx novaehollandiae) (a newly established Australian species), bittern (Botaurus poiciloptilus), and pukeko (Porphyrio melanotus).
The two species of grebe, the dabchick (Podiceps rufopectus) and crested grebe (Podiceps cristatus), are rarely seen, the latter being restricted to the South Island. Shags of inland waters are the little shag (Phalacrocorax melanoleucos), black shag (Phalacrocorax carbo), and the rare and local little black shag (Phalacrocorax sulcirostris).