Nene (Branta sandvicensis)

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 birds of one species is also found in New Zealand. 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 Hawaii 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 IslandThe relationships of the enigmatic Geochen rhuax to this genus are unresolved. It was another prehistoric Big Island form and remains known only from some parts of a single bird’s skeleton, which were much damaged because the bird apparently died in a volcanic eruption, with the bones being found in an ash-filled depression under a lava flow. A presumed relation to the shelducks proposed by Lester Short in 1970 was generally considered highly unlikely due to that group’s biogeography, but more recently, bones of a shelduck-like bird have been found on Kauai. Whether this latter anatid was indeed a shelduck is presently undetermined. Several fossil species of Branta have been described. Since the true geese are hardly distinguishable by anatomical features, the allocation of these to this genus is somewhat uncertain. A number of supposed prehistoric grey geese have been described from North America, partially from the same sites as species assigned to Branta. Whether these are correctly assigned, meaning that the genus Anser was once much more widespread than today and that it coexisted with Branta in freshwater habitat which it today does only most rarely, is not clear. Especially in the case of B. dickeyi and B. howardae, doubts have been expressed about its correct generic assignment