Unmasking the impact of second-generation anticoagulant rodenticides on Masked owls (<i>Tyto novaehollandiae castanops</i>) in Tasmania

Second-generation anticoagulant rodenticides (SGARs) are widely available in Australia for control of mammalian pests, without species distinction but particularly intended for rats and mice. Increasing rates of secondary exposure of non-target wildlife to these pesticides are well documented in avian and mammalian predators worldwide, including threatened species. We measured exposure levels of the threatened Tasmanian Masked Owl (<i>Tyto novaehollandiae castanops</i>) to a suite of anticoagulant rodenticides (ARs) available in Australia. We detected SGAR residues in 16 (94%) livers from 17 Masked Owls dying of varied causes. Residues of more than one AR were present in three birds. Likely toxic liver SGAR concentrations (&gt;0.1 mg/kg wet weight) were present in nine (53%) of the owls. SGAR toxicosis was confirmed at necropsy for two birds. This study adds to the growing evidence for widespread exposure of non-target wildlife to SGARs and further emphasises the need for stricter regulatory control of the sale and use of these pesticide products in Australia.