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The distribution, speciation and probable evolution of
New Zealand parakeets are outlined. Specific ecological
adaptations keep closely related sympatric species separate.
Examples are given of such ecological isolating mechanisms in
Antipodes and Chatham Island parakeets. Occasionally, where
man has drastically modified the environment, these barriers
break down and widespread hybridisation occurs, as on Mangere
Island, Chatham Islands. The existence of the very rare Chatham
Island Yellow-crowned Parakeet (Cyanoramphus auriceps
forbesi) is endangered by habitat changes and hybridisation.