To measure the costs and benefits of an aerial 1080 possum control operation to kereru and kaka in Whirinaki Forest Park, individuals of both species were radio-tagged from October 1998 to June 2002. We monitored birds in one treatment and one non-treatment study area to compare toxin-related mortality, nesting success and survival. The poison operation involved the spreading of non-toxic carrot baits on 1 May 2000, and the toxic baits on 17/18 May 2000.
In 1996 an eradication operation against two species of rats (Rattus norvegicus and R. exulans was conducted on Kapiti Island (1965 ha) and its small offshore islands. Trials with non-toxic baits had been carried out to help determine the risks to non-target species, and research was undertaken to collect baseline data for measuring the response of vegetation, invertebrates, reptiles and birds to the removal of rats.