A genus containing two extant parrot species from New Zealand and two extinct species from Norfolk Island and Chatham Island, New Zealand, respectively. All species are large stocky birds with short squarish tails. A defining characteristic of the genus is the tongue, which is tipped with a hair-like fringe. The superficial resemblance of this tongue to that of lorikeets has led some taxonomists to consider the two groups closely related, but DNA evidence shows they are not.
There are two surviving species and at least one well documented extinct species in the genus Nestor. Very little is known about the fourth, the Chatham kaka, which may have been conspecific with another kaka species.