Cygnus sumnerensis

Cygnus sumnerensis is an extinct swan (Anatidae) from Quaternary deposits of New Zealand, known from Sumner, Canterbury. A large herbivorous waterfowl, it inhabited freshwater lakes and coastal lagoons of the South Island before human arrival. New Zealand's isolation meant swans colonised it from Australia or Eurasia, and this species likely became flightless or semi-flightless in the absence of mammalian predators. It disappeared following Polynesian settlement around 700 years ago.