Secondary poisoning from rodenticides is a major welfare and conservation threat to barn owls, with second-generation anticoagulants accumulating in the food chain and causing prolonged internal bleeding.
Rodenticide secondary poisoning welfare is a case where a pest control decision creates diffuse, severe welfare harm across multiple non-target species. Barn owls are the most studied affected species, but kestrels, red kites, buzzards, otters, and polecats are all documented victims of secondary poisoning. The suffering caused by anticoagulant poisoning is prolonged — internal haemorrhage causes gradual deterioration over days before death. The availability of effective alternatives — first-generation rodenticides that have much lower accumulation risk, and snap traps that are lethal and immediate — means that much of this suffering is preventable through responsible pest management choices.