The genus Nestor contains three species: The Kākā (Nestor meridionalis), the Kea (N. notabilis), and the extinct Norfolk Island Kākā (N. productus). All three are thought to stem from a 'proto-Kākā', dwelling in the forests of New Zealand 15 million years ago. The closest relative is most likely the Kākāpō (Strigops habroptilus).
A 2005 sex chromosome spindlin DNA sequence study suggests that the Nestor species, and the Kākāpō in its own genus and tribe, comprise an ancient group that split off from all other Psittacidae before their radiation, but fossil evidence seems to contradict this; given the violent geological history of New Zealand (see, for example, Taupo Volcanic Zone), other explanations such as episodes of genetic drift seem better supported by evidence.
J Wildl Dis.: Evidence of lead exposure in a free-ranging population of kea (Nestor notabilis).(Author abstract)(Reprint)(Report)
Jun 01, 2010; Kea (Nestor notabilis) are high country parrots endemic to New Zealand. The foraging behavior and inquisitive nature of kea led...