The kaka Nestor meridionalis, a New Zealand parrot endangered by introduced wasps and mammals

Abstract

The kaka Nestor meridionalis is a forest parrot endemic to New Zealand, whose numbers have declined this century. We measured the energetics and breeding success of a remnant population of the South Island subspecies N.m. meridionalis in a beech Nothofagus forest modified by introduced browsing mammals. In six years only one successful kaka nest was found, and we suggest that a shortage of food with a high net energy return is limiting reproductive success. In summer, kaka obtained most of their daily energy requirements from honeydew excreted by the scale insect Ultracoelostomaa assimile, but in autumn this was no longer available. Introduced wasps Vespula spp. build up to plague proportions in autumn, and consumed most of the honeydew. The only female kaka to breed successfully was subsequently killed by a stoat Mustela erminea. We predict a decline in the density of South Island kaka in beech forests.