Varied success from the landscape-scale management of kiwi Apteryx spp. in five sanctuaries in New Zealand

In late 2000, five sanctuaries were established on the mainland of New Zealand for the express purpose of protecting populations of five kiwi Apteryx spp. taxa belonging to three species. Conservation management was undertaken at a landscape scale (10,000–20,000 ha) in each sanctuary to improve recruitment of kiwi. This was done by controlling introduced mammalian predators (especially stoats Mustela erminea), and/or by removing eggs and chicks from predation risk, and returning subadults when they were big enough to cope with stoats. Population modelling of the first five years of the sanctuary programme indicated that kiwi numbers in all five sanctuaries would increase as a result of the management. Calculated population increases varied from 0.6% per year at Okarito to 11.3% per year at Moehau, even though predator trapping was more intense at Okarito. The variation from site to site was explained by the widely different inherent productivity of the various kiwi taxa; widely different rates of adult mortality due to the presence or absence of dogs Canis familiaris and ferrets M. furo, the main predators of long-lived adult kiwi; and, local forest conditions affecting predator-prey cycles, and the density of stoats. As a result of this analysis, the management in four of the five sanctuaries has since been modified to try to achieve better overall gains for kiwi within the same operating budget.