Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. The extreme opposite of endemism is cosmopolitan distribution.
Physical, climatic, and biological factors can contribute to endemism. The Orange-breasted Sunbird is exclusively found in the fynbos vegetation zone of southwestern South Africa. Political factors can play a part if a species is protected, or actively hunted, in one jurisdiction but not another.
There are two subcategories of endemism – paleoendemism and neoendemism. Paleoendemism refers to a species that was formerly widespread but is now restricted to a smaller area. Neoendemism refers to a species that has recently arisen such as a species that has diverged and become reproductively isolated, or one that has formed following hybridization and is now classified as a separate species. This is a common process in plants, especially those that exhibit polyploidy.
Endemic types or species are especially likely to develop on biologically isolated areas such as islands because of their geographical isolation. This includes remote island groups, such as Hawaii, the Galápagos Islands, and Socotra, biologically isolated but not island areas such as the highlands of Ethiopia, or large bodies of water like Lake Baikal.
The Paradise Shelduck (Tadorna variegata) is a large goose-like duck endemic to New Zealand. It is a shelduck, a group of large goose-like birds which are part of the bird family Anatidae. The genus name Tadorna comes from Celtic roots and means "pied waterfowl". Known to the Māori as Pūtangitangi, but now commonly referred to as the "Paradise duck", it is a prized game bird. Both the male and female have striking plumage: the male has a black head and barred black body, the female a white head with a chestnut body.
The Paradise Shelducks usually live as pairs, grazing on grass and weeds, and will raid crops, particularly when molting.