Secondary poisoning of stoats (Mustela erminea), feral ferrets (Mustela furo),and feral house cats (Felis catus) by the anticoagulant poison, brodifacoum

Abstract

A poisoning operation using Talon 20P™, active ingredient brodifacoum, targeting rabbits (Oiyctolagus cuniculus) in coastal grasslands on the Otago Peninsula, New Zealand, also killed stoats (Mustela erminea), ferrets (Mustela furo), cats (Felis catus), and mice (Mus musculus) and probably possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus), rats (Rattus rattus), hares (Lepus europaeus occidentalis), and chaffinches (Fringilla coelebs). A new immigrant ferret also died 41 days after poisoning. If repeated in other habitats such as tussock grasslands and forests this method could greatly assist in restoration of mainland ecosystems and mitigation of bovine tuberculosis (Mycobacterium bovis) by controlling a variety of pests/ Tb carriers in one operation. The removal of small mammalian predators following poisoning operations could decrease immediate predation pressure on native wildlife. However, the efficacy of this multi‐species pest control method and unwanted side‐effects must be researched before its routine use. This research also demonstrates the potential threat of second‐generation anticoagulant poisons such as brodifacoum to small mammalian carnivores with high conservation value in their native countries.