The Norfolk kākā and the Chatham kākā have become extinct in recent times,[8][9] while the species of the genus Nelepsittacus have been extinct for 16 million years. All extant species, the kākāpō, kea, and the two subspecies of the kākā, are threatened.[10][11][12] Human activity caused the two extinctions and the decline of the other three species. Settlers introduced invasive species, such as pigs, cats, foxes, weasels, rats and possums, which eat the eggs of ground-nesting birds, and additional declines have been caused by hunting for food, killing as agricultural pests, habitat loss, and introduced wasps.[13][14][15]
The family diverged from the other parrots around 82 million years ago when New Zealand broke off from Gondwana, while the ancestors of the genera Nestor and Strigops diverged from each other between 60 and 80 million years ago.[16][17]
^Nestoridae and Strigopidae are described in the same article, Bonaparte, C.L. (1849) Conspectus Systematis Ornithologiae. Therefore, under rules of the ICZN, the first reviser determines priority, which is Bonaparte, C.L. (1850), Conspectus Generum Avium, E.J. Brill, Leyden.
^Worthy, Trevor H.; Tennyson, Alan J. D.; Scofield, R. Paul (2011). "An early Miocene diversity of parrots (Aves, Strigopidae, Nestorinae) from New Zealand". Journal of Vertebrate Paleontology. 31 (5): 1102–16. doi:10.1080/02724634.2011.595857. S2CID86361015.
^ abForshaw, Joseph M.; Cooper, William T. (1981) [1973, 1978]. Parrots of the World (corrected second ed.). David & Charles, Newton Abbot, London. ISBN0-7153-7698-5.