Branta

The black geese of the genus Branta are waterfowl belonging to the true geese and swans subfamily Anserinae. They occur in the northern coastal regions of the Palearctic and all over North America, migrating to more southernly coasts in winter, and as resident birds in the Hawaiian Islands. Alone in the Southern Hemisphere, a self-sustaining feral population derived from introduced Canada geese is also found in New Zealand. The scientific name Branta is a Latinised form of Old Norse Brandgás, 'burnt (black) goose'. The black geese derive their vernacular name for the prominent areas of black coloration found in all species. They can be distinguished from all other true geese by their legs and feet, which are black or very dark grey. Furthermore, they have black bills and large areas of black on the head and neck, with white (ochre in one species) markings that can be used to tell apart most species. As with most geese, their undertail and uppertail coverts are white. They are also on average smaller than other geese, though some very large taxa are known, which rival the swan goose and the black-necked swan in size. The Eurasian species of black geese have a more coastal distribution compared to the grey geese which share the same general area of occurrence, not being found far inland even in winter (except for occasional stray birds or individuals escaped from captivity). This does not hold true for the American and Pacific species, in whose ranges grey geese are for the most part absent. Based on the Taxonomy in Flux from John Boyd's website. 6–8 living species of black geese are known. In addition, one species has been described from subfossil remains found in the Hawaiian Islands, where it became extinct in prehistoric times. Another undescribed prehistoric species from the Big Island of Hawai‘i was extremely large and flightless; it is tentatively assigned to this genus due to being very peculiar. It is fairly certain that at least another species of this genus awaits discovery on the Big Island, judging from the facts that at least one species of Branta was found on every major Hawaiian island, and that remains of such birds have not been intentionally searched for on the Big Island (but see below).