New Zealand Journal of Zoology abstracts
From small Maria to massive Campbell: forty years of rat eradications from New Zealand islands
David R. Towns
School of Biological Sciences
Victoria University of Wellington
and
Science and Research Unit
Department of Conservation
Private Bag 68 908, Newton
Auckland, New Zealand*
Keith G. Broome
Northern Regional Office
Department of Conservation
P.O. Box 112
Hamilton, New Zealand
Abstract Over the last four decades the eradication of rats from islands around New Zealand has moved from accidental eradication following the exploratory use of baits for rat control to carefully planned complex eradications of rats and cats (Felis catus) on large islands. Introduced rodents have now been eradicated from more than 90 islands. Of these successful campaigns, those on Breaksea Island, the Mercury Islands, Kapiti Island, and Tuhua Island are used here as case studies because they represent milestones for techniques used or results achieved. Successful methods used on islands range from bait stations and silos serviced on foot to aerial spread by helicopters using satellite navigation systems. The development of these methods has benefited from adaptive management. By applying lessons learned from previous operations the size, complexity, and cost effectiveness of the campaigns has gradually increased. The islands now permanently cleared of introduced rodents are being used for restoration of island-seabird systems and recovery of threatened species such as large flightless invertebrates, lizards, tuatara, forest birds, and some species of plants. The most ambitious campaigns have been on remote subantarctic Campbell Island (11 300 ha) and warm temperate Raoul Island (2938 ha), aimed to provide long-term benefits for endemic plant and animal species including land and seabirds. Other islands that could benefit from rat removal are close inshore and within the natural dispersal range of rats and stoats (Mustela erminea). Priorities for future development therefore include more effective methods for detecting rodent invasions, especially ship rats (Rattus rattus) and mice (Mus musculus), broader community involvement in invasion prevention, and improved understanding of reinvasion risk management.
Keywords kiore; Pacific rat; Rattus exulans; Norway rat; R. norvegicus; ship rat; R. rattus; eradication; adaptive management; Breaksea Island, Mercury Islands; Kapiti Island, Tuhua Island; rodenticide; brodifacoum; aerial spread; legal constraints; Resource Management Act 1991; invasion biology; benefits; costs; cultural issues
Z03016 Received 24 April 2003; accepted 31 July 2003; online publication date 16 October 2003
New Zealand Journal of Zoology, 2003, Vol. 30: 377-398
0301-4223/03/3004-0377 $7.00/0 © The Royal Society of New Zealand 2003
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