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New Zealand’s Use of Brodifacoum in Eradication Efforts and Current Investigation of New Baits and Toxins


Rodent eradication on islands has transitioned over 30 years in New Zealand through stages of initial scepticism, to early accidental and experimental successes, and now to the current bold large-scale aerial applications over increasingly large and complex island ecosystems. Starting in the 1970s and 1980s, gaining momentum in the 1990s, and continuing to the present day, islands once occupied by rodents are now being reclaimed. Until the mid 1980s, very few islands were entirely free of animal pests. Rodent eradication on islands, using bait in stations and baits applied from the air, has been spectacularly successful. To date, more than 90 islands around New Zealand have been cleared of rodents, and brodifacoum use has had an obvious benefit on valuable island ecosystems. The tactical use of toxic bait to protect island populations of indigenous birds, reptiles, and invertebrates endangered by rats and mice continues to be refined to enable larger and more complex islands to be cleared of rodents. New bait types that are especially attractive to mice as well as rats, long-life baits, new toxins, and tunnel delivery systems will augment existing bait types to aid future eradication programmes and help prevent re-invasions. New developments will need to be ethically and socially acceptable and demonstrate clear advantages in non-target impact as well as efficacy in achieving eradication. These endeavours are part of global efforts to eradicate invasives and manage islands to protect native birds and other important fauna and flora.

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