Evaluation of secondary poisoning hazards to ferrets and weka from the rodenticide coumatetralyl

Abstract

We investigated the secondary poisoning hazards of the rodenticide coumatetralyl to a predatory and scavenging mammal and bird. Wistar rats, which had been poisoned with Racumin^® baits containing 375 ppm coumatetralyl, were fed to 10 captive ferrets (Mustela furo) and 10 weka (Gallirallus australis) for 3 consecutive days. Nine ferrets ate 764 ± 95 g kg^–1 (83% by weight) of the rat carcasses offered and two died. Weka ate 258 ± 32 g kg^–1 (25% by weight) of the rat carcasses, preferring the internal organs. There were no deaths and no obvious signs of ill health in any weka. These results suggest that predatory and scavenging bird and mammal species, in general, will be placed only at comparatively low risk from secondary poisoning from coumatetralyl.