a1 Centre for Conservation Biology, School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
a2 Kakapo Management Group, Biodiversity Recovery Unit, STIS, Department of Conservation, PO Box 10 420, Wellington, New Zealand.
We review the conservation history and describe the current status of the Kakapo Strigops habroptilus, a large New Zealand parrot which has been reduced to only 54 individuals through predation by introduced mammals, and is now threatened with extinction. Unique amongst parrots, Kakapo are both flightless and nocturnal. They have an unusual mating system in which females nest and raise their young unaided by males, after mating at traditional “courts” at which males display visually and vocally. Mating occurs naturally only in seasons of heavy fruiting of podocarp trees. A decline in range and abundance of Kakapo followed the introduction of alien mammals last century, and culminated in their reduction to a single breeding population on Stewart Island. Following a severe episode of predation by feral cats Felis catus, all known birds from this last population were translocated to a series of cat-free offshore islands. Adult survival on these island sanctuaries has been high (c. 98% per annum), but productivity has been low, with only six young (including a single female) raised to independence since 1982. Reasons for this low productivity are the naturally intermittent breeding of Kakapo, the low numbers of nesting females, high rates of egg infertility (~ 40%), and the early death of most nestlings through starvation or suspected predation by Polynesian rats Rattus exulans. These rats are present on both of the island sanctuaries where nesting has occurred. The Kakapo sex ratio is biased in favour of males (34:20) and only 8 of the 19 adult females are known to have laid fertile eggs in the past 10 years. Management of all remaining birds is now highly intensive, involving radio-tagging of all individuals, the provision of supplementary food, attempts to manipulate matings, nest surveillance, and protection against rat predation.